export ETCDCTL_API=3
ENDPOINTS=localhost:2379

etcdctl --endpoints=${ENDPOINTS} role add root
etcdctl --endpoints=${ENDPOINTS} role get root

etcdctl --endpoints=${ENDPOINTS} user add root
etcdctl --endpoints=${ENDPOINTS} user grant-role root root
etcdctl --endpoints=${ENDPOINTS} user get root

etcdctl --endpoints=${ENDPOINTS} role add role0
etcdctl --endpoints=${ENDPOINTS} role grant-permission role0 readwrite foo
etcdctl --endpoints=${ENDPOINTS} user add user0
etcdctl --endpoints=${ENDPOINTS} user grant-role user0 role0

etcdctl --endpoints=${ENDPOINTS} auth enable
# now all client requests go through auth

etcdctl --endpoints=${ENDPOINTS} --user=user0:123 put foo bar
etcdctl --endpoints=${ENDPOINTS} get foo
# permission denied, user name is empty because the request does not issue an authentication request
etcdctl --endpoints=${ENDPOINTS} --user=user0:123 get foo
# user0 can read the key foo
etcdctl --endpoints=${ENDPOINTS} --user=user0:123 get foo1

--name 'default'
  Human-readable name for this member.
--data-dir '${name}.etcd'
  Path to the data directory.
--wal-dir ''
  Path to the dedicated wal directory.
--snapshot-count '10000'
  Number of committed transactions to trigger a snapshot to disk.
--heartbeat-interval '100'
  Time (in milliseconds) of a heartbeat interval.
--election-timeout '1000'
  Time (in milliseconds) for an election to timeout. See tuning documentation for details.
--initial-election-tick-advance 'true'
  Whether to fast-forward initial election ticks on boot for faster election.
--listen-peer-urls 'http://localhost:2380'
  List of URLs to listen on for peer traffic.
--listen-client-urls 'http://localhost:2379'
  List of URLs to listen on for client grpc traffic and http as long as --listen-client-http-urls is not specified.
--listen-client-http-urls ''
  List of URLs to listen on for http only client traffic. Enabling this flag removes http services from --listen-client-urls.
--max-snapshots '5'
  Maximum number of snapshot files to retain (0 is unlimited).
--max-wals '5'
  Maximum number of wal files to retain (0 is unlimited).
--memory-mlock
  Enable to enforce etcd pages (in particular bbolt) to stay in RAM.
--quota-backend-bytes '0'
  Raise alarms when backend size exceeds the given quota (0 defaults to low space quota).
--backend-bbolt-freelist-type 'map'
  BackendFreelistType specifies the type of freelist that boltdb backend uses(array and map are supported types).
--backend-batch-interval ''
  BackendBatchInterval is the maximum time before commit the backend transaction.
--backend-batch-limit '0'
  BackendBatchLimit is the maximum operations before commit the backend transaction.
--max-txn-ops '128'
  Maximum number of operations permitted in a transaction.
--max-request-bytes '1572864'
  Maximum client request size in bytes the server will accept.
--grpc-keepalive-min-time '5s'
  Minimum duration interval that a client should wait before pinging server.
--grpc-keepalive-interval '2h'
  Frequency duration of server-to-client ping to check if a connection is alive (0 to disable).
--grpc-keepalive-timeout '20s'
  Additional duration of wait before closing a non-responsive connection (0 to disable).
--socket-reuse-port 'false'
  Enable to set socket option SO_REUSEPORT on listeners allowing rebinding of a port already in use.
--socket-reuse-address 'false'
  Enable to set socket option SO_REUSEADDR on listeners allowing binding to an address in TIME_WAIT state.

--initial-advertise-peer-urls 'http://localhost:2380'
  List of this member's peer URLs to advertise to the rest of the cluster.
--initial-cluster 'default=http://localhost:2380'
  Initial cluster configuration for bootstrapping.
--initial-cluster-state 'new'
  Initial cluster state ('new' or 'existing').
--initial-cluster-token 'etcd-cluster'
  Initial cluster token for the etcd cluster during bootstrap.
  Specifying this can protect you from unintended cross-cluster interaction when running multiple clusters.
--advertise-client-urls 'http://localhost:2379'
  List of this member's client URLs to advertise to the public.
  The client URLs advertised should be accessible to machines that talk to etcd cluster. etcd client libraries parse these URLs to connect to the cluster.
--discovery ''
  Discovery URL used to bootstrap the cluster.
--discovery-fallback 'proxy'
  Expected behavior ('exit' or 'proxy') when discovery services fails.
  "proxy" supports v2 API only.
--discovery-proxy ''
  HTTP proxy to use for traffic to discovery service.
--discovery-srv ''
  DNS srv domain used to bootstrap the cluster.
--discovery-srv-name ''
  Suffix to the dns srv name queried when bootstrapping.
--strict-reconfig-check 'true'
  Reject reconfiguration requests that would cause quorum loss.
--pre-vote 'true'
  Enable the raft Pre-Vote algorithm to prevent disruption when a node that has been partitioned away rejoins the cluster.
--auto-compaction-retention '0'
  Auto compaction retention length. 0 means disable auto compaction.
--auto-compaction-mode 'periodic'
  Interpret 'auto-compaction-retention' one of: periodic|revision. 'periodic' for duration based retention, defaulting to hours if no time unit is provided (e.g. '5m'). 'revision' for revision number based retention.
--enable-v2 'false'
  Accept etcd V2 client requests. Deprecated and to be decommissioned in v3.6.
--v2-deprecation 'not-yet'
  Phase of v2store deprecation. Allows to opt-in for higher compatibility mode.
  Supported values:
    'not-yet'                // Issues a warning if v2store have meaningful content (default in v3.5)
    'write-only'             // Custom v2 state is not allowed (default in v3.6 and v3.7)
    'write-only-skip-check'  // Custom v2 state is not supported and, if present, will be ignored (available in v3.5.32+, v3.6.13+, and v3.7.0+). Use this option at your own risk.
    'write-only-drop-data'   // Custom v2 state will get DELETED ! (planned default in v3.8)
    'gone'                   // v2store is not maintained any longer.

--cert-file ''
  Path to the client server TLS cert file.
--key-file ''
  Path to the client server TLS key file.
--client-cert-auth 'false'
  Enable client cert authentication.
  It's recommended to enable client cert authentication to prevent attacks from unauthenticated clients (e.g. CVE-2023-44487), especially when running etcd as a public service.
--client-crl-file ''
  Path to the client certificate revocation list file.
--client-cert-allowed-hostname ''
  Comma-separated list of SAN hostnames for client cert authentication.
--trusted-ca-file ''
  Path to the client server TLS trusted CA cert file.
  Note setting this parameter will also automatically enable client cert authentication no matter what value is set for `--client-cert-auth`.
--auto-tls 'false'
  Client TLS using generated certificates.
--peer-cert-file ''
  Path to the peer server TLS cert file.
--peer-key-file ''
  Path to the peer server TLS key file.
--peer-client-cert-auth 'false'
  Enable peer client cert authentication.
  It's recommended to enable peer client cert authentication to prevent attacks from unauthenticated forged peers (e.g. CVE-2023-44487).
--peer-trusted-ca-file ''
  Path to the peer server TLS trusted CA file.
--peer-cert-allowed-cn ''
  Comma-separated list of allowed CNs for inter-peer TLS authentication.
--peer-cert-allowed-hostname ''
  Comma-separated list of allowed SAN hostnames for inter-peer TLS authentication.
--peer-auto-tls 'false'
  Peer TLS using self-generated certificates if --peer-key-file and --peer-cert-file are not provided.
--self-signed-cert-validity '1'
  The validity period of the client and peer certificates that are automatically generated by etcd when you specify ClientAutoTLS and PeerAutoTLS, the unit is year, and the default is 1.
--peer-crl-file ''
  Path to the peer certificate revocation list file.
--cipher-suites ''
  Comma-separated list of supported TLS cipher suites between client/server and peers (empty will be auto-populated by Go).
--cors '*'
  Comma-separated whitelist of origins for CORS, or cross-origin resource sharing, (empty or * means allow all).
--host-whitelist '*'
  Acceptable hostnames from HTTP client requests, if server is not secure (empty or * means allow all).
--tls-min-version 'TLS1.2'
  Minimum TLS version supported by etcd.
--tls-max-version ''
  Maximum TLS version supported by etcd (empty will be auto-populated by Go).

--auth-token 'simple'
  Specify a v3 authentication token type and its options ('simple' or 'jwt').
--bcrypt-cost 10
  Specify the cost / strength of the bcrypt algorithm for hashing auth passwords. Valid values are between 4 and 31.
--auth-token-ttl 300
  Time (in seconds) of the auth-token-ttl.

--enable-pprof 'false'
  Enable runtime profiling data via HTTP server. Address is at client URL + "/debug/pprof/"
--metrics 'basic'
  Set level of detail for exported metrics, specify 'extensive' to include server side grpc histogram metrics.
--listen-metrics-urls ''
  List of URLs to listen on for the metrics and health endpoints.

--logger 'zap'
  Currently only supports 'zap' for structured logging.
--log-outputs 'default'
  Specify 'stdout' or 'stderr' to skip journald logging even when running under systemd, or list of comma separated output targets.
--log-level 'info'
  Configures log level. Only supports debug, info, warn, error, panic, or fatal.
--log-format 'json'
  Configures log format. Only supports json, console.
--enable-log-rotation 'false'
  Enable log rotation of a single log-outputs file target.
--log-rotation-config-json '{"maxsize": 100, "maxage": 0, "maxbackups": 0, "localtime": false, "compress": false}'
  Configures log rotation if enabled with a JSON logger config. MaxSize(MB), MaxAge(days,0=no limit), MaxBackups(0=no limit), LocalTime(use computers local time), Compress(gzip)".
--warning-unary-request-duration '300ms'
  Set time duration after which a warning is logged if a unary request takes more than this duration.

--enable-distributed-tracing 'false'
  Enable distributed tracing.
--distributed-tracing-address 'localhost:4317'
  Distributed tracing collector address.
--distributed-tracing-service-name 'etcd'
  Distributed tracing service name, must be the same across all etcd instances.
--distributed-tracing-instance-id ''
  Distributed tracing instance ID, must be unique for each etcd instance.
--distributed-tracing-sampling-rate '0'
  Number of samples to collect per million spans for distributed tracing.

--proxy 'off'
  Proxy mode setting ('off', 'readonly' or 'on').
--proxy-failure-wait 5000
  Time (in milliseconds) an endpoint will be held in a failed state.
--proxy-refresh-interval 30000
  Time (in milliseconds) of the endpoints refresh interval.
--proxy-dial-timeout 1000
  Time (in milliseconds) for a dial to timeout.
--proxy-write-timeout 5000
  Time (in milliseconds) for a write to timeout.
--proxy-read-timeout 0
  Time (in milliseconds) for a read to timeout.

--corrupt-check-time '0s'
  Duration of time between cluster corruption check passes.
--compact-hash-check-time '1m'
  Duration of time between leader checks followers compaction hashes.
--compaction-batch-limit 1000
  CompactionBatchLimit sets the maximum revisions deleted in each compaction batch.
--peer-skip-client-san-verification 'false'
  Skip verification of SAN field in client certificate for peer connections.
--watch-progress-notify-interval '10m'
  Duration of periodical watch progress notification.
--warning-apply-duration '100ms'
  Warning is generated if requests take more than this duration.
--bootstrap-defrag-threshold-megabytes
  Enable the defrag during etcd server bootstrap on condition that it will free at least the provided threshold of disk space. Needs to be set to non-zero value to take effect.
--max-learners '1'
  Set the max number of learner members allowed in the cluster membership.
--compaction-sleep-interval
  Sets the sleep interval between each compaction batch.
--downgrade-check-time
  Duration of time between two downgrade status checks.
--snapshot-catchup-entries
  Number of entries for a slow follower to catch up after compacting the raft storage entries.

--feature-gates=AllAlpha=true|false
  Enables or disables all alpha features. Default is false.
--feature-gates=AllBeta=true|false
  Enables or disables all beta features. Default is false.
--feature-gates=CompactHashCheck=true
  Enables leader to periodically check follower compaction hashes.
  Replaces: --experimental-compact-hash-check-enabled
--feature-gates=InitialCorruptCheck=true
  Enables corruption check before serving client/peer traffic.
  Replaces: --experimental-initial-corrupt-check
--feature-gates=LeaseCheckpoint=true
  ExperimentalEnableLeaseCheckpoint enables primary lessor to persist lease remainingTTL to prevent indefinite auto-renewal of long lived leases.
  Replaces: --experimental-enable-lease-checkpoint
--feature-gates=LeaseCheckpointPersist=true
  Enable persisting remainingTTL to prevent indefinite auto-renewal of long lived leases. Always enabled in v3.6. Should be used to ensure smooth upgrade from v3.5 clusters with this feature enabled.
  Replaces: --experimental-enable-lease-checkpoint-persist
--feature-gates=SetMemberLocalAddr=true
  Allows setting a member’s local address.
--feature-gates=StopGRPCServiceOnDefrag=true
  Enable etcd gRPC service to stop serving client requests on defragmentation.
  Replaces: --experimental-stop-grpc-service-on-defrag
--feature-gates=TxnModeWriteWithSharedBuffer=true
  Enable the write transaction to use a shared buffer in its readonly check operations.
  Replaces: --experimental-txn-mode-write-with-shared-buffer

--force-new-cluster 'false'
  Force to create a new one-member cluster.
--unsafe-no-fsync 'false'
  Disables fsync, unsafe, will cause data loss.

$ etcd --name infra0 --data-dir infra0 \
  --cert-file=/path/to/server.crt --key-file=/path/to/server.key \
  --advertise-client-urls=https://127.0.0.1:2379 --listen-client-urls=https://127.0.0.1:2379

$ curl --cacert /path/to/ca.crt https://127.0.0.1:2379/v2/keys/foo -XPUT -d value=bar -v

$ etcd --name infra0 --data-dir infra0 \
  --client-cert-auth --trusted-ca-file=/path/to/ca.crt --cert-file=/path/to/server.crt --key-file=/path/to/server.key \
  --advertise-client-urls https://127.0.0.1:2379 --listen-client-urls https://127.0.0.1:2379

$ curl --cacert /path/to/ca.crt https://127.0.0.1:2379/v2/keys/foo -XPUT -d value=bar -v

$ curl --cacert /path/to/ca.crt --cert /path/to/client.crt --key /path/to/client.key \
  -L https://127.0.0.1:2379/v2/keys/foo -XPUT -d value=bar -v

{
    "action": "set",
    "node": {
        "createdIndex": 12,
        "key": "/foo",
        "modifiedIndex": 12,
        "value": "bar"
    }
}

$ etcd \
  --cert-file ./server.crt \
  --key-file ./server.key \
  --trusted-ca-file ./ca.crt \
  --cipher-suites TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384

# valid cipher suite
$ curl \
  --cacert /path/to/ca.crt \
  --cert /path/to/client.crt \
  --key /path/to/client.key \
  -L [CLIENT-URL]/metrics \
  --ciphers ECDHE-RSA-AES128-GCM-SHA256

# request succeeds
etcd_server_version{server_version="3.2.22"} 1
...

# invalid cipher suite
$ curl \
  --cacert /path/to/ca.crt \
  --cert /path/to/client.crt \
  --key /path/to/client.key \
  -L [CLIENT-URL]/metrics \
  --ciphers ECDHE-RSA-DES-CBC3-SHA

# request fails with
(35) error:14094410:SSL routines:ssl3_read_bytes:sslv3 alert handshake failure

DISCOVERY_URL=... # from https://discovery.etcd.io/new

# member1
$ etcd --name infra1 --data-dir infra1 \
  --peer-client-cert-auth --peer-trusted-ca-file=/path/to/ca.crt --peer-cert-file=/path/to/member1.crt --peer-key-file=/path/to/member1.key \
  --initial-advertise-peer-urls=https://10.0.1.10:2380 --listen-peer-urls=https://10.0.1.10:2380 \
  --discovery ${DISCOVERY_URL}

# member2
$ etcd --name infra2 --data-dir infra2 \
  --peer-client-cert-auth --peer-trusted-ca-file=/path/to/ca.crt --peer-cert-file=/path/to/member2.crt --peer-key-file=/path/to/member2.key \
  --initial-advertise-peer-urls=https://10.0.1.11:2380 --listen-peer-urls=https://10.0.1.11:2380 \
  --discovery ${DISCOVERY_URL}

DISCOVERY_URL=... # from https://discovery.etcd.io/new

# member1
$ etcd --name infra1 --data-dir infra1 \
  --auto-tls --peer-auto-tls \
  --initial-advertise-peer-urls=https://10.0.1.10:2380 --listen-peer-urls=https://10.0.1.10:2380 \
  --discovery ${DISCOVERY_URL}

# member2
$ etcd --name infra2 --data-dir infra2 \
  --auto-tls --peer-auto-tls \
  --initial-advertise-peer-urls=https://10.0.1.11:2380 --listen-peer-urls=https://10.0.1.11:2380 \
  --discovery ${DISCOVERY_URL}

curl: (60) SSL certificate problem: Invalid certificate chain

$ curl -k https://127.0.0.1:2379/v2/keys/foo -Xput -d value=bar -v

{
  "CN": "etcd peer",
  "hosts": [
    "*.example.default.svc",
    "*.example.default.svc.cluster.local",
    "10.138.0.27"
  ],
  "key": {
    "algo": "rsa",
    "size": 2048
  },
  "names": [
    {
      "C": "US",
      "L": "CA",
      "ST": "San Francisco"
    }
  ]
}

{
  "CN": "etcd peer",
  "hosts": [
    "b.com"
  ],

{
  "CN": "etcd peer",
  "hosts": [
    "invalid.domain",
    "10.138.0.2"
  ],

{
  "CN": "etcd peer",
  "hosts": [
    "*.example.default.svc",
    "*.example.default.svc.cluster.local"
  ],

{
  "CN": "etcd.local",
  "hosts": [
    "m1.etcd.local",
    "127.0.0.1",
    "localhost"
  ],

{
  "CN": "etcd.local",
  "hosts": [
    "m2.etcd.local",
    "127.0.0.1",
    "localhost"
  ],

{
  "CN": "etcd.local",
  "hosts": [
    "m3.etcd.local",
    "127.0.0.1",
    "localhost"
  ],

$ etcd --peer-cert-allowed-cn m1.etcd.local

I | embed: rejected connection from "127.0.0.1:48044" (error "CommonName authentication failed", ServerName "m1.etcd.local")
I | embed: rejected connection from "127.0.0.1:55702" (error "remote error: tls: bad certificate", ServerName "m3.etcd.local")

etcd --peer-cert-allowed-cn etcd.local

I | pkg/netutil: resolving m3.etcd.local:32380 to 127.0.0.1:32380
I | pkg/netutil: resolving m2.etcd.local:22380 to 127.0.0.1:22380
I | pkg/netutil: resolving m1.etcd.local:2380 to 127.0.0.1:2380
I | etcdserver: published {Name:m3 ClientURLs:[https://m3.etcd.local:32379]} to cluster 9db03f09b20de32b
I | embed: ready to serve client requests
I | etcdserver: published {Name:m1 ClientURLs:[https://m1.etcd.local:2379]} to cluster 9db03f09b20de32b
I | embed: ready to serve client requests
I | etcdserver: published {Name:m2 ClientURLs:[https://m2.etcd.local:22379]} to cluster 9db03f09b20de32b
I | embed: ready to serve client requests
I | embed: serving client requests on 127.0.0.1:32379
I | embed: serving client requests on 127.0.0.1:22379
I | embed: serving client requests on 127.0.0.1:2379

{
  "CN": "etcd.local",
  "hosts": [
    "127.0.0.1"
  ],

$ kubectl apply --filename etcd.yaml

$ kubectl get pods
NAME     READY   STATUS    RESTARTS   AGE
etcd-0   1/1     Running   0          24m
etcd-1   1/1     Running   0          24m
etcd-2   1/1     Running   0          24m

$ kubectl exec -it etcd-0 -- etcdctl member list -wtable
+------------------+---------+--------+-------------------------+-------------------------+------------+
|        ID        | STATUS  |  NAME  |       PEER ADDRS        |      CLIENT ADDRS       | IS LEARNER |
+------------------+---------+--------+-------------------------+-------------------------+------------+
| 4f98c3545405a0b0 | started | etcd-2 | http://etcd-2.etcd:2380 | http://etcd-2.etcd:2379 |      false |
| a394e0ee91773643 | started | etcd-0 | http://etcd-0.etcd:2380 | http://etcd-0.etcd:2379 |      false |
| d10297b8d2f01265 | started | etcd-1 | http://etcd-1.etcd:2380 | http://etcd-1.etcd:2379 |      false |
+------------------+---------+--------+-------------------------+-------------------------+------------+

# file: etcd.yaml
---
apiVersion: v1
kind: Service
metadata:
  name: etcd
  namespace: default
spec:
  type: ClusterIP
  clusterIP: None
  selector:
    app: etcd
  ##
  ## Ideally we would use SRV records to do peer discovery for initialization.
  ## Unfortunately discovery will not work without logic to wait for these to
  ## populate in the container. This problem is relatively easy to overcome by
  ## making changes to prevent the etcd process from starting until the records
  ## have populated. The documentation on statefulsets briefly talk about it.
  ##   https://kubernetes.io/docs/concepts/workloads/controllers/statefulset/#stable-network-id
  publishNotReadyAddresses: true
  ##
  ## The naming scheme of the client and server ports match the scheme that etcd
  ## uses when doing discovery with SRV records.
  ports:
  - name: etcd-client
    port: 2379
  - name: etcd-server
    port: 2380
  - name: etcd-metrics
    port: 8080
---
apiVersion: apps/v1
kind: StatefulSet
metadata:
  namespace: default
  name: etcd
spec:
  ##
  ## The service name is being set to leverage the service headlessly.
  ## https://kubernetes.io/docs/concepts/services-networking/service/#headless-services
  serviceName: etcd
  ##
  ## If you are increasing the replica count of an existing cluster, you should
  ## also update the --initial-cluster-state flag as noted further down in the
  ## container configuration.
  replicas: 3
  ##
  ## For initialization, the etcd pods must be available to eachother before
  ## they are "ready" for traffic. The "Parallel" policy makes this possible.
  podManagementPolicy: Parallel
  ##
  ## To ensure availability of the etcd cluster, the rolling update strategy
  ## is used. For availability, there must be at least 51% of the etcd nodes
  ## online at any given time.
  updateStrategy:
    type: RollingUpdate
  ##
  ## This is label query over pods that should match the replica count.
  ## It must match the pod template's labels. For more information, see the
  ## following documentation:
  ##   https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/#label-selectors
  selector:
    matchLabels:
      app: etcd
  ##
  ## Pod configuration template.
  template:
    metadata:
      ##
      ## The labeling here is tied to the "matchLabels" of this StatefulSet and
      ## "affinity" configuration of the pod that will be created.
      ##
      ## This example's labeling scheme is fine for one etcd cluster per
      ## namespace, but should you desire multiple clusters per namespace, you
      ## will need to update the labeling schema to be unique per etcd cluster.
      labels:
        app: etcd
      annotations:
        ##
        ## This gets referenced in the etcd container's configuration as part of
        ## the DNS name. It must match the service name created for the etcd
        ## cluster. The choice to place it in an annotation instead of the env
        ## settings is because there should only be 1 service per etcd cluster.
        serviceName: etcd
    spec:
      ##
      ## Configuring the node affinity is necessary to prevent etcd servers from
      ## ending up on the same hardware together.
      ##
      ## See the scheduling documentation for more information about this:
      ##   https://kubernetes.io/docs/concepts/scheduling-eviction/assign-pod-node/#node-affinity
      affinity:
        ## The podAntiAffinity is a set of rules for scheduling that describe
        ## when NOT to place a pod from this StatefulSet on a node.
        podAntiAffinity:
          ##
          ## When preparing to place the pod on a node, the scheduler will check
          ## for other pods matching the rules described by the labelSelector
          ## separated by the chosen topology key.
          requiredDuringSchedulingIgnoredDuringExecution:
          ## This label selector is looking for app=etcd
          - labelSelector:
              matchExpressions:
              - key: app
                operator: In
                values:
                - etcd
            ## This topology key denotes a common label used on nodes in the
            ## cluster. The podAntiAffinity configuration essentially states
            ## that if another pod has a label of app=etcd on the node, the
            ## scheduler should not place another pod on the node.
            ##   https://kubernetes.io/docs/reference/labels-annotations-taints/#kubernetesiohostname
            topologyKey: "kubernetes.io/hostname"
      ##
      ## Containers in the pod
      containers:
      ## This example only has this etcd container.
      - name: etcd
        image: quay.io/coreos/etcd:v3.7.0
        imagePullPolicy: IfNotPresent
        ports:
        - name: etcd-client
          containerPort: 2379
        - name: etcd-server
          containerPort: 2380
        - name: etcd-metrics
          containerPort: 8080
        ##
        ## These probes will fail over TLS for self-signed certificates, so etcd
        ## is configured to deliver metrics over port 8080 further down.
        ##
        ## As mentioned in the "Monitoring etcd" page, /readyz and /livez were
        ## added in v3.5.12. Prior to this, monitoring required extra tooling
        ## inside the container to make these probes work.
        ##
        ## The values in this readiness probe should be further validated, it
        ## is only an example configuration.
        readinessProbe:
          httpGet:
            path: /readyz
            port: 8080
          initialDelaySeconds: 10
          periodSeconds: 5
          timeoutSeconds: 5
          successThreshold: 1
          failureThreshold: 30
        ## The values in this liveness probe should be further validated, it
        ## is only an example configuration.
        livenessProbe:
          httpGet:
            path: /livez
            port: 8080
          initialDelaySeconds: 15
          periodSeconds: 10
          timeoutSeconds: 5
          failureThreshold: 3
        env:
        ##
        ## Environment variables defined here can be used by other parts of the
        ## container configuration. They are interpreted by Kubernetes, instead
        ## of in the container environment.
        ##
        ## These env vars pass along information about the pod.
        - name: K8S_NAMESPACE
          valueFrom:
            fieldRef:
             fieldPath: metadata.namespace
        - name: HOSTNAME
          valueFrom:
            fieldRef:
             fieldPath: metadata.name
        - name: SERVICE_NAME
          valueFrom:
            fieldRef:
              fieldPath: metadata.annotations['serviceName']
        ##
        ## Configuring etcdctl inside the container to connect to the etcd node
        ## in the container reduces confusion when debugging.
        - name: ETCDCTL_ENDPOINTS
          value: $(HOSTNAME).$(SERVICE_NAME):2379
        ##
        ## TLS client configuration for etcdctl in the container.
        ## These files paths are part of the "etcd-client-certs" volume mount.
        # - name: ETCDCTL_KEY
        #   value: /etc/etcd/certs/client/tls.key
        # - name: ETCDCTL_CERT
        #   value: /etc/etcd/certs/client/tls.crt
        # - name: ETCDCTL_CACERT
        #   value: /etc/etcd/certs/client/ca.crt
        ##
        ## Use this URI_SCHEME value for non-TLS clusters.
        - name: URI_SCHEME
          value: "http"
        ## TLS: Use this URI_SCHEME for TLS clusters.
        # - name: URI_SCHEME
        # value: "https"
        ##
        ## If you're using a different container, the executable may be in a
        ## different location. This example uses the full path to help remove
        ## ambiguity to you, the reader.
        ## Often you can just use "etcd" instead of "/usr/local/bin/etcd" and it
        ## will work because the $PATH includes a directory containing "etcd".
        command:
        - /usr/local/bin/etcd
        ##
        ## Arguments used with the etcd command inside the container.
        args:
        ##
        ## Configure the name of the etcd server.
        - --name=$(HOSTNAME)
        ##
        ## Configure etcd to use the persistent storage configured below.
        - --data-dir=/data
        ##
        ## In this example we're consolidating the WAL into sharing space with
        ## the data directory. This is not ideal in production environments and
        ## should be placed in it's own volume.
        - --wal-dir=/data/wal
        ##
        ## URL configurations are parameterized here and you shouldn't need to
        ## do anything with these.
        - --listen-peer-urls=$(URI_SCHEME)://0.0.0.0:2380
        - --listen-client-urls=$(URI_SCHEME)://0.0.0.0:2379
        - --advertise-client-urls=$(URI_SCHEME)://$(HOSTNAME).$(SERVICE_NAME):2379
        ##
        ## This must be set to "new" for initial cluster bootstrapping. To scale
        ## the cluster up, this should be changed to "existing" when the replica
        ## count is increased. If set incorrectly, etcd makes an attempt to
        ## start but fail safely.
        - --initial-cluster-state=new
        ##
        ## Token used for cluster initialization. The recommendation for this is
        ## to use a unique token for every cluster. This example parameterized
        ## to be unique to the namespace, but if you are deploying multiple etcd
        ## clusters in the same namespace, you should do something extra to
        ## ensure uniqueness amongst clusters.
        - --initial-cluster-token=etcd-$(K8S_NAMESPACE)
        ##
        ## The initial cluster flag needs to be updated to match the number of
        ## replicas configured. When combined, these are a little hard to read.
        ## Here is what a single parameterized peer looks like:
        ##   etcd-0=$(URI_SCHEME)://etcd-0.$(SERVICE_NAME):2380
        - --initial-cluster=etcd-0=$(URI_SCHEME)://etcd-0.$(SERVICE_NAME):2380,etcd-1=$(URI_SCHEME)://etcd-1.$(SERVICE_NAME):2380,etcd-2=$(URI_SCHEME)://etcd-2.$(SERVICE_NAME):2380
        ##
        ## The peer urls flag should be fine as-is.
        - --initial-advertise-peer-urls=$(URI_SCHEME)://$(HOSTNAME).$(SERVICE_NAME):2380
        ##
        ## This avoids probe failure if you opt to configure TLS.
        - --listen-metrics-urls=http://0.0.0.0:8080
        ##
        ## These are some configurations you may want to consider enabling, but
        ## should look into further to identify what settings are best for you.
        # - --auto-compaction-mode=periodic
        # - --auto-compaction-retention=10m
        ##
        ## TLS client configuration for etcd, reusing the etcdctl env vars.
        # - --client-cert-auth
        # - --trusted-ca-file=$(ETCDCTL_CACERT)
        # - --cert-file=$(ETCDCTL_CERT)
        # - --key-file=$(ETCDCTL_KEY)
        ##
        ## TLS server configuration for etcdctl in the container.
        ## These files paths are part of the "etcd-server-certs" volume mount.
        # - --peer-client-cert-auth
        # - --peer-trusted-ca-file=/etc/etcd/certs/server/ca.crt
        # - --peer-cert-file=/etc/etcd/certs/server/tls.crt
        # - --peer-key-file=/etc/etcd/certs/server/tls.key
        ##
        ## This is the mount configuration.
        volumeMounts:
        - name: etcd-data
          mountPath: /data
        ##
        ## TLS client configuration for etcdctl
        # - name: etcd-client-tls
        #   mountPath: "/etc/etcd/certs/client"
        #   readOnly: true
        ##
        ## TLS server configuration
        # - name: etcd-server-tls
        #   mountPath: "/etc/etcd/certs/server"
        #   readOnly: true
      volumes:
      ##
      ## TLS client configuration
      # - name: etcd-client-tls
      #   secret:
      #     secretName: etcd-client-tls
      #     optional: false
      ##
      ## TLS server configuration
      # - name: etcd-server-tls
      #   secret:
      #     secretName: etcd-server-tls
      #     optional: false
  ##
  ## This StatefulSet will uses the volumeClaimTemplate field to create a PVC in
  ## the cluster for each replica. These PVCs can not be easily resized later.
  volumeClaimTemplates:
  - metadata:
      name: etcd-data
    spec:
      accessModes: ["ReadWriteOnce"]
      ##
      ## In some clusters, it is necessary to explicitly set the storage class.
      ## This example will end up using the default storage class.
      # storageClassName: ""
      resources:
        requests:
          storage: 1Gi

$ helm upgrade --install --create-namespace --namespace cert-manager cert-manager cert-manager --repo https://charts.jetstack.io --set crds.enabled=true

# file: issuer.yaml
apiVersion: cert-manager.io/v1
kind: ClusterIssuer
metadata:
  name: selfsigned
spec:
  selfSigned: {}

# file: certificates.yaml
---
apiVersion: cert-manager.io/v1
kind: Certificate
metadata:
  name: etcd-server
  namespace: default
spec:
  secretName: etcd-server-tls
  issuerRef:
    name: selfsigned
    kind: ClusterIssuer
  commonName: etcd
  dnsNames:
  - etcd
  - etcd.default
  - etcd.default.svc.cluster.local
  - etcd-0
  - etcd-0.etcd
  - etcd-0.etcd.default
  - etcd-0.etcd.default.svc
  - etcd-0.etcd.default.svc.cluster.local
  - etcd-1
  - etcd-1.etcd
  - etcd-1.etcd.default
  - etcd-1.etcd.default.svc
  - etcd-1.etcd.default.svc.cluster.local
  - etcd-2
  - etcd-2.etcd
  - etcd-2.etcd.default
  - etcd-2.etcd.default.svc
  - etcd-2.etcd.default.svc.cluster.local
---
apiVersion: cert-manager.io/v1
kind: Certificate
metadata:
  name: etcd-client
  namespace: default
spec:
  secretName: etcd-client-tls
  issuerRef:
    name: selfsigned
    kind: ClusterIssuer
  commonName: etcd
  dnsNames:
  - etcd
  - etcd.default
  - etcd.default.svc.cluster.local
  - etcd-0
  - etcd-0.etcd
  - etcd-0.etcd.default
  - etcd-0.etcd.default.svc
  - etcd-0.etcd.default.svc.cluster.local
  - etcd-1
  - etcd-1.etcd
  - etcd-1.etcd.default
  - etcd-1.etcd.default.svc
  - etcd-1.etcd.default.svc.cluster.local
  - etcd-2
  - etcd-2.etcd
  - etcd-2.etcd.default
  - etcd-2.etcd.default.svc
  - etcd-2.etcd.default.svc.cluster.local

$ ETCDCTL_API=3 etcdctl --endpoints $ENDPOINT snapshot save snapshot.db

$ etcdutl snapshot status snapshot.db -w table
+---------+----------+------------+------------+
|  HASH   | REVISION | TOTAL KEYS | TOTAL SIZE |
+---------+----------+------------+------------+
| 7ef846e |   485261 |      11642 |      94 MB |
+---------+----------+------------+------------+

$ etcdutl snapshot restore snapshot.db --data-dir output-dir

$ etcdutl snapshot restore snapshot.db --bump-revision 1000000000 --mark-compacted --data-dir output-dir

$ etcdutl snapshot restore snapshot.db \
  --name m1 \
  --data-dir m1.etcd \
  --initial-cluster m1=http://host1:2380,m2=http://host2:2380,m3=http://host3:2380 \
  --initial-cluster-token etcd-cluster-1 \
  --initial-advertise-peer-urls http://host1:2380

$ etcdctl snapshot save snapshot.db

$ etcdutl snapshot restore snapshot.db \
  --name m1 \
  --data-dir m1_data_dir.etcd \
  --initial-cluster m1=http://host1:2380,m2=http://host2:2380,m3=http://host3:2380 \
  --initial-cluster-token etcd-cluster-1 \
  --initial-advertise-peer-urls http://host1:2380
$ etcdutl snapshot restore snapshot.db \
  --name m2 \
  --data-dir m2_data_dir.etcd \
  --initial-cluster m1=http://host1:2380,m2=http://host2:2380,m3=http://host3:2380 \
  --initial-cluster-token etcd-cluster-1 \
  --initial-advertise-peer-urls http://host2:2380
$ etcdutl snapshot restore snapshot.db \
  --name m3 \
  --data-dir m3_data_dir.etcd \
  --initial-cluster m1=http://host1:2380,m2=http://host2:2380,m3=http://host3:2380 \
  --initial-cluster-token etcd-cluster-1 \
  --initial-advertise-peer-urls http://host3:2380

$ etcd \
  --name m1 \
  --data-dir m1_data_dir.etcd \
  --listen-client-urls http://host1:2379 \
  --advertise-client-urls http://host1:2379 \
  --listen-peer-urls http://host1:2380 &
$ etcd \
  --name m2 \
  --data-dir m2_data_dir.etcd \
  --listen-client-urls http://host2:2379 \
  --advertise-client-urls http://host2:2379 \
  --listen-peer-urls http://host2:2380 &
$ etcd \
  --name m3 \
  --data-dir m3_data_dir.etcd \
  --listen-client-urls http://host3:2379 \
  --advertise-client-urls http://host3:2379 \
  --listen-peer-urls http://host3:2380 &

$ etcd gateway start --endpoints=infra0.example.com:2379,infra1.example.com:2379,infra2.example.com:2379
2016-08-16 11:21:18.867350 I | tcpproxy: ready to proxy client requests to [...]

$ dig +noall +answer SRV _etcd-client._tcp.example.com
_etcd-client._tcp.example.com. 300 IN SRV 0 0 2379 infra0.example.com.
_etcd-client._tcp.example.com. 300 IN SRV 0 0 2379 infra1.example.com.
_etcd-client._tcp.example.com. 300 IN SRV 0 0 2379 infra2.example.com.

$ dig +noall +answer infra0.example.com infra1.example.com infra2.example.com
infra0.example.com.  300  IN  A  10.0.1.10
infra1.example.com.  300  IN  A  10.0.1.11
infra2.example.com.  300  IN  A  10.0.1.12

$ etcd gateway start --discovery-srv=example.com
2016-08-16 11:21:18.867350 I | tcpproxy: ready to proxy client requests to [...]

$ etcd grpc-proxy start --endpoints=infra0.example.com,infra1.example.com,infra2.example.com --listen-addr=127.0.0.1:2379

$ ETCDCTL_API=3 etcdctl --endpoints=127.0.0.1:2379 put foo bar
OK
$ ETCDCTL_API=3 etcdctl --endpoints=127.0.0.1:2379 get foo
foo
bar

$ etcd grpc-proxy start --endpoints=localhost:2379 \
  --listen-addr=127.0.0.1:23790 \
  --advertise-client-url=127.0.0.1:23790 \
  --resolver-prefix="___grpc_proxy_endpoint" \
  --resolver-ttl=60

$ etcd grpc-proxy start --endpoints=localhost:2379 \
  --listen-addr=127.0.0.1:23791 \
  --advertise-client-url=127.0.0.1:23791 \
  --resolver-prefix="___grpc_proxy_endpoint" \
  --resolver-ttl=60

ETCDCTL_API=3 etcdctl --endpoints=http://localhost:23790 member list --write-out table

+----+---------+--------------------------------+------------+-----------------+
| ID | STATUS  |              NAME              | PEER ADDRS |  CLIENT ADDRS   |
+----+---------+--------------------------------+------------+-----------------+
|  0 | started | Gyu-Hos-MBP.sfo.coreos.systems |            | 127.0.0.1:23791 |
|  0 | started | Gyu-Hos-MBP.sfo.coreos.systems |            | 127.0.0.1:23790 |
+----+---------+--------------------------------+------------+-----------------+

cli, err := clientv3.New(clientv3.Config{
    Endpoints: []string{"http://localhost:23790"},
})
if err != nil {
    log.Fatal(err)
}
defer cli.Close()

// fetch registered grpc-proxy endpoints
if err := cli.Sync(context.Background()); err != nil {
    log.Fatal(err)
}

$ etcd grpc-proxy start --endpoints=localhost:2379 \
  --listen-addr=127.0.0.1:23792 \
  --advertise-client-url=127.0.0.1:23792

ETCDCTL_API=3 etcdctl --endpoints=http://localhost:23792 member list --write-out table

+----+---------+--------------------------------+------------+-----------------+
| ID | STATUS  |              NAME              | PEER ADDRS |  CLIENT ADDRS   |
+----+---------+--------------------------------+------------+-----------------+
|  0 | started | Gyu-Hos-MBP.sfo.coreos.systems |            | 127.0.0.1:23792 |
+----+---------+--------------------------------+------------+-----------------+

$ etcd grpc-proxy start --endpoints=localhost:2379 \
  --listen-addr=127.0.0.1:23790 \
  --namespace=my-prefix/

$ ETCDCTL_API=3 etcdctl --endpoints=localhost:23790 put my-key abc
# OK
$ ETCDCTL_API=3 etcdctl --endpoints=localhost:23790 get my-key
# my-key
# abc
$ ETCDCTL_API=3 etcdctl --endpoints=localhost:2379 get my-prefix/my-key
# my-prefix/my-key
# abc

$ etcd --listen-client-urls https://localhost:2379 --advertise-client-urls https://localhost:2379 --cert-file=peer.crt --key-file=peer.key --trusted-ca-file=ca.crt --client-cert-auth

# fails
$ ETCDCTL_API=3 etcdctl --endpoints=http://localhost:2379 endpoint status
# works
$ ETCDCTL_API=3 etcdctl --endpoints=https://localhost:2379 --cert=client.crt --key=client.key --cacert=ca.crt endpoint status

$ etcd grpc-proxy start --endpoints=https://localhost:2379 --listen-addr localhost:12379 --cert client.crt --key client.key --cacert=ca.crt --insecure-skip-tls-verify &

$ ETCDCTL_API=3 etcdctl --endpoints=http://localhost:12379 put abc def
# OK

$ etcd grpc-proxy start \
  --endpoints https://localhost:2379 \
  --metrics-addr https://0.0.0.0:4443 \
  --listen-addr 127.0.0.1:23790 \
  --key client.key \
  --key-file proxy-server.key \
  --cert client.crt \
  --cert-file proxy-server.crt \
  --cacert ca.pem \
  --trusted-ca-file proxy-ca.pem

 $ curl --cacert proxy-ca.pem --key proxy-client.key --cert proxy-client.crt https://127.0.0.1:23790/metrics --http1.1

# compact up to revision 3
$ etcdctl compact 3

$ etcdctl get --rev=2 somekey
Error:  rpc error: code = 11 desc = etcdserver: mvcc: required revision has been compacted

# keep one hour of history
$ etcd --auto-compaction-retention=1h

0hr  (rev = 1)
1hr  (rev = 10)
...
8hr  (rev = 80)
9hr  (rev = 90)
10hr (rev = 100, Compact(1))
11hr (rev = 110, Compact(10))
...

# keep 1000 revisions
$ etcd --auto-compaction-mode=revision --auto-compaction-retention=1000

$ etcdctl defrag
Finished defragmenting etcd member[127.0.0.1:2379]

$ etcdctl defrag --cluster
Finished defragmenting etcd member[http://127.0.0.1:2379]
Finished defragmenting etcd member[http://127.0.0.1:22379]
Finished defragmenting etcd member[http://127.0.0.1:32379]

etcdutl defrag --data-dir <path-to-etcd-data-dir>

# set a very small 16 MiB quota
$ etcd --quota-backend-bytes=$((16*1024*1024))

# fill keyspace
$ while [ 1 ]; do dd if=/dev/urandom bs=1024 count=1024  | ETCDCTL_API=3 etcdctl put key  || break; done
...
Error:  rpc error: code = 8 desc = etcdserver: mvcc: database space exceeded
# confirm quota space is exceeded
$ ETCDCTL_API=3 etcdctl --write-out=table endpoint status
+----------------+------------------+-----------+---------+-----------+-----------+------------+
|    ENDPOINT    |        ID        |  VERSION  | DB SIZE | IS LEADER | RAFT TERM | RAFT INDEX |
+----------------+------------------+-----------+---------+-----------+-----------+------------+
| 127.0.0.1:2379 | bf9071f4639c75cc | 2.3.0+git | 18 MB   | true      |         2 |       3332 |
+----------------+------------------+-----------+---------+-----------+-----------+------------+
# confirm alarm is raised
$ ETCDCTL_API=3 etcdctl alarm list
memberID:13803658152347727308 alarm:NOSPACE

# get current revision
$ rev=$(ETCDCTL_API=3 etcdctl --endpoints=:2379 endpoint status --write-out="json" | egrep -o '"revision":[0-9]*' | egrep -o '[0-9].*')
# compact away all old revisions
$ ETCDCTL_API=3 etcdctl compact $rev
compacted revision 1516
# defragment away excessive space
$ ETCDCTL_API=3 etcdctl defrag
Finished defragmenting etcd member[127.0.0.1:2379]
# disarm alarm
$ ETCDCTL_API=3 etcdctl alarm disarm
memberID:13803658152347727308 alarm:NOSPACE
# test puts are allowed again
$ ETCDCTL_API=3 etcdctl put newkey 123
OK

$ etcdctl snapshot save backup.db
$ etcdutl --write-out=table snapshot status backup.db
+----------+----------+------------+------------+
|   HASH   | REVISION | TOTAL KEYS | TOTAL SIZE |
+----------+----------+------------+------------+
| fe01cf57 |       10 |          7 | 2.1 MB     |
+----------+----------+------------+------------+

$ go tool pprof http://localhost:2379/debug/pprof/profile
Fetching profile from http://localhost:2379/debug/pprof/profile
Please wait... (30s)
Saved profile in /home/etcd/pprof/pprof.etcd.localhost:2379.samples.cpu.001.pb.gz
Entering interactive mode (type "help" for commands)
(pprof) top10
310ms of 480ms total (64.58%)
Showing top 10 nodes out of 157 (cum >= 10ms)
    flat  flat%   sum%        cum   cum%
   130ms 27.08% 27.08%      130ms 27.08%  runtime.futex
    70ms 14.58% 41.67%       70ms 14.58%  syscall.Syscall
    20ms  4.17% 45.83%       20ms  4.17%  github.com/coreos/etcd/vendor/golang.org/x/net/http2/hpack.huffmanDecode
    20ms  4.17% 50.00%       30ms  6.25%  runtime.pcvalue
    20ms  4.17% 54.17%       50ms 10.42%  runtime.schedule
    10ms  2.08% 56.25%       10ms  2.08%  github.com/coreos/etcd/vendor/github.com/coreos/etcd/etcdserver.(*EtcdServer).AuthInfoFromCtx
    10ms  2.08% 58.33%       10ms  2.08%  github.com/coreos/etcd/vendor/github.com/coreos/etcd/etcdserver.(*EtcdServer).Lead
    10ms  2.08% 60.42%       10ms  2.08%  github.com/coreos/etcd/vendor/github.com/coreos/etcd/pkg/wait.(*timeList).Trigger
    10ms  2.08% 62.50%       10ms  2.08%  github.com/coreos/etcd/vendor/github.com/prometheus/client_golang/prometheus.(*MetricVec).hashLabelValues
    10ms  2.08% 64.58%       10ms  2.08%  github.com/coreos/etcd/vendor/golang.org/x/net/http2.(*Framer).WriteHeaders

$ curl -L http://localhost:2379/metrics | grep -v debugging # ignore unstable debugging metrics

# HELP etcd_disk_backend_commit_duration_seconds The latency distributions of commit called by backend.
# TYPE etcd_disk_backend_commit_duration_seconds histogram
etcd_disk_backend_commit_duration_seconds_bucket{le="0.002"} 72756
etcd_disk_backend_commit_duration_seconds_bucket{le="0.004"} 401587
etcd_disk_backend_commit_duration_seconds_bucket{le="0.008"} 405979
etcd_disk_backend_commit_duration_seconds_bucket{le="0.016"} 406464
...

curl -k http://localhost:2379/readyz?verbose

[+]data_corruption ok
[+]serializable_read ok
[+]linearizable_read ok
ok

curl -k http://localhost:2379/readyz?exclude=data_corruption

PROMETHEUS_VERSION="2.0.0"
wget https://github.com/prometheus/prometheus/releases/download/v$PROMETHEUS_VERSION/prometheus-$PROMETHEUS_VERSION.linux-amd64.tar.gz -O /tmp/prometheus-$PROMETHEUS_VERSION.linux-amd64.tar.gz
tar -xvzf /tmp/prometheus-$PROMETHEUS_VERSION.linux-amd64.tar.gz --directory /tmp/ --strip-components=1
/tmp/prometheus -version

cat > /tmp/test-etcd.yaml <<EOF
global:
  scrape_interval: 10s
scrape_configs:
  - job_name: test-etcd
    static_configs:
    - targets: ['10.240.0.32:2379','10.240.0.33:2379','10.240.0.34:2379']
EOF
cat /tmp/test-etcd.yaml

nohup /tmp/prometheus \
    -config.file /tmp/test-etcd.yaml \
    -web.listen-address ":9090" \
    -storage.local.path "test-etcd.data" >> /tmp/test-etcd.log  2>&1 &

# write to leader
benchmark --endpoints=${HOST_1} --target-leader --conns=1 --clients=1 \
    put --key-size=8 --sequential-keys --total=10000 --val-size=256
benchmark --endpoints=${HOST_1} --target-leader  --conns=100 --clients=1000 \
    put --key-size=8 --sequential-keys --total=100000 --val-size=256

# write to all members
benchmark --endpoints=${HOST_1},${HOST_2},${HOST_3} --conns=100 --clients=1000 \
    put --key-size=8 --sequential-keys --total=100000 --val-size=256

# Single connection read requests
benchmark --endpoints=${HOST_1},${HOST_2},${HOST_3} --conns=1 --clients=1 \
    range YOUR_KEY --consistency=l --total=10000
benchmark --endpoints=${HOST_1},${HOST_2},${HOST_3} --conns=1 --clients=1 \
    range YOUR_KEY --consistency=s --total=10000

# Many concurrent read requests
benchmark --endpoints=${HOST_1},${HOST_2},${HOST_3} --conns=100 --clients=1000 \
    range YOUR_KEY --consistency=l --total=100000
benchmark --endpoints=${HOST_1},${HOST_2},${HOST_3} --conns=100 --clients=1000 \
    range YOUR_KEY --consistency=s --total=100000

$ etcdctl member list
6e3bd23ae5f1eae0: name=node2 peerURLs=http://localhost:23802 clientURLs=http://127.0.0.1:23792
924e2e83e93f2560: name=node3 peerURLs=http://localhost:23803 clientURLs=http://127.0.0.1:23793
a8266ecf031671f3: name=node1 peerURLs=http://localhost:23801 clientURLs=http://127.0.0.1:23791

$ etcdctl member update a8266ecf031671f3 --peer-urls=http://10.0.1.10:2380
Updated member with ID a8266ecf031671f3 in cluster

$ etcdctl member remove a8266ecf031671f3
Removed member a8266ecf031671f3 from cluster

$ etcdctl member add infra3 --peer-urls=http://10.0.1.13:2380
added member 9bf1b35fc7761a23 to cluster

ETCD_NAME="infra3"
ETCD_INITIAL_CLUSTER="infra0=http://10.0.1.10:2380,infra1=http://10.0.1.11:2380,infra2=http://10.0.1.12:2380,infra3=http://10.0.1.13:2380"
ETCD_INITIAL_CLUSTER_STATE=existing

$ export ETCD_NAME="infra3"
$ export ETCD_INITIAL_CLUSTER="infra0=http://10.0.1.10:2380,infra1=http://10.0.1.11:2380,infra2=http://10.0.1.12:2380,infra3=http://10.0.1.13:2380"
$ export ETCD_INITIAL_CLUSTER_STATE=existing
$ etcd --listen-client-urls http://10.0.1.13:2379 --advertise-client-urls http://10.0.1.13:2379 --listen-peer-urls http://10.0.1.13:2380 --initial-advertise-peer-urls http://10.0.1.13:2380 --data-dir %data_dir%

$ etcdctl member add infra3 --peer-urls=http://10.0.1.13:2380 --learner
Member 9bf1b35fc7761a23 added to cluster a7ef944b95711739

ETCD_NAME="infra3"
ETCD_INITIAL_CLUSTER="infra0=http://10.0.1.10:2380,infra1=http://10.0.1.11:2380,infra2=http://10.0.1.12:2380,infra3=http://10.0.1.13:2380"
ETCD_INITIAL_CLUSTER_STATE=existing

$ etcd --name infra3 \
  --initial-cluster infra0=http://10.0.1.10:2380,infra1=http://10.0.1.11:2380,infra2=http://10.0.1.12:2380 \
  --initial-cluster-state existing
etcdserver: assign ids error: the member count is unequal
exit 1

$ etcd --name infra4 \
  --initial-cluster infra0=http://10.0.1.10:2380,infra1=http://10.0.1.11:2380,infra2=http://10.0.1.12:2380,infra4=http://10.0.1.14:2380 \
  --initial-cluster-state existing
etcdserver: assign ids error: unmatched member while checking PeerURLs
exit 1

$ etcd
etcd: this member has been permanently removed from the cluster. Exiting.
exit 1

etcdctl --endpoints=127.0.0.1:2379 endpoint status