etcd

references:
* etcd tutorials
* How to Add and Remove Members
clustering guide | clustering.md
runtime reconfiguration
* configuration flags
etcd.conf.yml.sample
setting up etcd cluster with tls authentication enabled
configuring etcd rbac
deploy a secure etcd cluster
set up a high availability etcd cluster with kubeadm
creating highly available clusters with kubeadm
etcd backup and restore in kubernetes: step by step
operating etcd clusters for kubernetes | operating etcd clusters for kubernetes
understand how the etcd cluster is configured
tutorial: set up a secure and highly available etcd cluster

extenal etcd topology certificates located in : /etc/etcd/ssl
extenal etcd
[!TIP] You need:
- Three or more machines that meet kubeadm's minimum requirements for the control-plane nodes. Having an odd number of control plane nodes can help with leader selection in the case of machine or zone failure.
  including a container runtime, already set up and working
- Three or more machines that meet kubeadm's minimum requirements for the workers
  including a container runtime, already set up and working
- Full network connectivity between all machines in the cluster (public or private network)
- Superuser privileges on all machines using sudo
  You can use a different tool; this guide uses sudo in the examples.
- SSH access from one device to all nodes in the system
- kubeadm and kubelet already installed on all machines.
And you also need:
- Three or more additional machines, that will become etcd cluster members. Having an odd number of members in the etcd cluster is a requirement for achieving optimal voting quorum.
  These machines again need to have kubeadm and kubelet installed.
  These machines also require a container runtime, that is already set up and working.
See External etcd topology for context.
stacked etcd topology certificates located in : /etc/kubernetes/pki/etcd
stacked etcd
[!TIP] You need:
- Three or more machines that meet kubeadm's minimum requirements for the control-plane nodes. Having an odd number of control plane nodes can help with leader selection in the case of machine or zone failure.
  including a container runtime, already set up and working
- Three or more machines that meet kubeadm's minimum requirements for the workers
  including a container runtime, already set up and working
- Full network connectivity between all machines in the cluster (public or private network)
- Superuser privileges on all machines using sudo
  You can use a different tool; this guide uses sudo in the examples.
- SSH access from one device to all nodes in the system
- kubeadm and kubelet already installed on all machines.
See Stacked etcd topology for context.

extenal etcd

certificates

$ sudo mkdir -p /etc/etcd/ssl

certificate signing request

generate the etcd certificates in major kubernetes master. and sync to the others following kuberentes masters.

$ sudo bash -c 'cat > /etc/etcd/ssl/ca-config.json' << EOF
{
    "signing": {
        "default": {
            "expiry": "43800h"
        },
        "profiles": {
            "server": {
                "expiry": "43800h",
                "usages": [
                    "signing",
                    "key encipherment",
                    "server auth",
                    "client auth"
                ]
            },
            "client": {
                "expiry": "43800h",
                "usages": [
                    "signing",
                    "key encipherment",
                    "client auth"
                ]
            },
            "peer": {
                "expiry": "43800h",
                "usages": [
                    "signing",
                    "key encipherment",
                    "server auth",
                    "client auth"
                ]
            }
        }
    }
}
EOF

$ sudo bash -c 'cat > /etc/etcd/ssl/ca-csr.json' << EOF
{
    "CN": "etcd",
    "key": {
        "algo": "rsa",
        "size": 2048
    }
}
EOF

$ sudo /usr/local/bin/cfssl gencert \
       -initca ca-csr.json \
       | sudo /usr/local/bin/cfssljson -bare ca -

client

$ sudo bash -c 'cat > /etc/etcd/ssl/client.json' << EOF
{
    "CN": "client",
    "key": {
        "algo": "ecdsa",
        "size": 256
    }
}
EOF

$ sudo /usr/local/bin/cfssl gencert \
       -ca=ca.pem \
       -ca-key=ca-key.pem \
       -config=ca-config.json \
       -profile=client client.json \
       | sudo /usr/local/bin/cfssljson -bare client

result

$ ls
ca-config.json  ca.csr  ca-csr.json  ca-key.pem  ca.pem  client.csr  client.json  client-key.pem  client.pem

sync to the others masters

$ for _host in master02 master03; do
    ssh ${_host} 'sudo mkdir -p /etc/etcd/ssl'
    rsync -avzrlpgoDP \
          --rsync-path='sudo rsync' \
          /etc/etcd/ssl/*.pem \
          ${_host}:/etc/etcd/ssl/
    rsync -avzrlpgoDP \
          --rsync-path='sudo rsync' \
          /etc/etcd/ssl/ca-config.json \
          ${_host}:/etc/etcd/ssl/
  done

configuration

etcd.service

$ sudo bash -c 'cat >/etc/systemd/system/etcd.service' << EOF
[Install]
WantedBy=multi-user.target

[Unit]
Description=Etcd Server
Documentation=https://github.com/marslo/mytools
Conflicts=etcd.service
Conflicts=etcd2.service

[Service]
Type=notify
WorkingDirectory=/var/lib/etcd/
Restart=always
RestartSec=5s
EnvironmentFile=-/etc/etcd/etcd.conf
ExecStart=/bin/bash -c "GOMAXPROCS=$(nproc) /usr/local/bin/etcd"
Restart=on-failure
RestartSec=5
LimitNOFILE=65536

[Install]
WantedBy=multi-user.target
EOF

etcd.conf

$ etcdInitialCluster="master01=https://192.168.100.200:2380"
etcdInitialCluster+=",master02=https://192.168.100.201:2380"
etcdInitialCluster+=",master03=https://192.168.100.202:2380"

$ interface=$(netstat -nr | grep -E 'UG|UGSc' | grep -E '^0.0.0|default' | grep -E '[0-9.]{7,15}' | awk -F' ' '{print $NF}')
$ ipAddr=$(ip a s "${interface}" | sed -rn 's|\W*inet[^6]\W*([0-9\.]{7,15}).*$|\1|p')

$ sudo bash -c 'cat > /etc/etcd/etcd.conf' << EOF
ETCD_NAME=$(hostname)
ETCD_DATA_DIR="/var/lib/etcd/default.etcd"
#ETCD_WAL_DIR=""
#ETCD_SNAPSHOT_COUNT="10000"
#ETCD_HEARTBEAT_INTERVAL="100"
#ETCD_ELECTION_TIMEOUT="1000"
ETCD_LISTEN_PEER_URLS="https://0.0.0.0:2380"
ETCD_LISTEN_CLIENT_URLS="https://0.0.0.0:2379"
#ETCD_MAX_SNAPSHOTS="5"
#ETCD_MAX_WALS="5"
#ETCD_CORS=""

#[cluster]
ETCD_INITIAL_ADVERTISE_PEER_URLS="https://${ipAddr}:2380"
# if you use different ETCD_NAME (e.g. test), set ETCD_INITIAL_CLUSTER value for this name, i.e. "test=http://
..."
ETCD_INITIAL_CLUSTER="${etcdInitialCluster}"
ETCD_INITIAL_CLUSTER_STATE="new"
ETCD_INITIAL_CLUSTER_TOKEN="etcd-cluster"
ETCD_ADVERTISE_CLIENT_URLS="https://${ipAddr}:2379"
#ETCD_DISCOVERY=""
#ETCD_DISCOVERY_SRV=""
#ETCD_DISCOVERY_FALLBACK="proxy"
#ETCD_DISCOVERY_PROXY=""
#ETCD_STRICT_RECONFIG_CHECK="false"
#ETCD_AUTO_COMPACTION_RETENTION="0"

#[proxy]
#ETCD_PROXY="off"
#ETCD_PROXY_FAILURE_WAIT="5000"
#ETCD_PROXY_REFRESH_INTERVAL="30000"
#ETCD_PROXY_DIAL_TIMEOUT="1000"
#ETCD_PROXY_WRITE_TIMEOUT="5000"
#ETCD_PROXY_READ_TIMEOUT="0"

#[security]
ETCD_CERT_FILE="/etc/etcd/ssl/server.pem"
ETCD_KEY_FILE="/etc/etcd/ssl/server-key.pem"
ETCD_CLIENT_CERT_AUTH="true"
ETCD_TRUSTED_CA_FILE="/etc/etcd/ssl/ca.pem"
ETCD_AUTO_TLS="true"
ETCD_PEER_CERT_FILE="/etc/etcd/ssl/peer.pem"
ETCD_PEER_KEY_FILE="/etc/etcd/ssl/peer-key.pem"
#ETCD_PEER_CLIENT_CERT_AUTH="false"
ETCD_PEER_TRUSTED_CA_FILE="/etc/etcd/ssl/ca.pem"
ETCD_PEER_AUTO_TLS="true"

#[logging]
#ETCD_DEBUG="false"
# examples for -log-package-levels etcdserver=WARNING,security=DEBUG
#ETCD_LOG_PACKAGE_LEVELS=""
#[profiling]
#ETCD_ENABLE_PPROF="false"
#ETCD_METRICS="basic"
EOF

enable service

$ sudo systemctl daemon-reload
$ sudo systemctl enable --now etcd
$ sudo systemctl start etcd.service

verify

$ sudo systemctl status etcd
$ sudo /usr/local/bin/etcdctl --ca-file /etc/etcd/ssl/ca.pem \
                              --cert-file /etc/etcd/ssl/client.pem \
                              --key-file /etc/etcd/ssl/client-key.pem \
                              --endpoints https://192.168.100.200:2379,https://192.168.100.201:2379,https://192.168.100.202:2379 \
                              cluster-health

tips

$ alias etcdctl="sudo /usr/local/bin/etcdctl --ca-file /etc/etcd/ssl/ca.pem --cert-file /etc/etcd/ssl/client.pem --key-file /etc/etcd/ssl/client-key.pem --endpoints https://192.168.100.200:2379,https://192.168.100.201:2379,https://192.168.100.202:2379"
$ etcdctl cluster-health
member ae76391b129**** is healthy: got healthy result from https://192.168.100.200:2379
member cda996b3ea5a*** is healthy: got healthy result from https://192.168.100.201:2379
member e295a3c1654e*** is healthy: got healthy result from https://192.168.100.202:2379
cluster is healthy

stacked etcd

configuration

$ sudo cat /etc/kubernetes/manifests/etcd.yaml

operate

debug into stacked etcd cluster

references:

replacing a failed etcd member It is recommended to back up this directory to an off-cluster location before removing the contents. You can remove this backup after a successful restore
$ sudo rm -rf /var/lib/etcd/*

# or
$ sudo mv /var/lib/etcd/member{,.backup}

$ docker run -it \
             -v /var/lib/etcd:/var/lib/etcd \
             -v /etc/kubernetes/pki/etcd:/etc/kubernetes/pki/etcd \
             -p 2380:2380 \
             -p 2379:2379 \
             --network=host \
             k8s.gcr.io/etcd:3.2.24

$ etcdctl --ca-file /etc/kubernetes/pki/etcd/ca.crt \
          --cert-file /etc/kubernetes/pki/etcd/peer.crt \
          --key-file /etc/kubernetes/pki/etcd/peer.key \
          -endpoints=https://10.0.0.1:2379,https://10.0.0.2:2379,https://10.0.0.3:2379 \
          member list

$ etcdctl member list
$ etcdctl member remove <id>

# peerURL using port 2380 by default. clientURL using 2379 by default
$ etcdctl member add <hostname> <peerURL:2380>

$ etcdctl member update <id> <peerURL:2380>

add tag --initial-cluster-state=existing in /etc/kubernetes/manifests/etcd.yaml

$ sudo cat /etc/kubernetes/manifests/etcd.yaml
apiVersion: v1
kind: Pod
metadata:
  ...
spec:
  containers:
  - command:
    - etcd
    - --advertise-client-urls=https://10.0.0.2:2379
    - --initial-advertise-peer-urls=https://10.0.0.2:2380
    - --initial-cluster=member1=https://10.0.0.1:2380,member3=https://10.0.0.3:2380,member2=https://10.0.0.2:2380
    - --listen-client-urls=https://10.0.0.2:2379
    - --listen-peer-urls=https://10.0.0.2:2380
    - --name=member2
    - --cert-file=/etc/kubernetes/pki/etcd/server.crt
    - --client-cert-auth=true
    - --data-dir=/var/lib/etcd
    - --key-file=/etc/kubernetes/pki/etcd/server.key
    - --peer-cert-file=/etc/kubernetes/pki/etcd/peer.crt
    - --peer-client-cert-auth=true
    - --peer-key-file=/etc/kubernetes/pki/etcd/peer.key
    - --peer-trusted-ca-file=/etc/kubernetes/pki/etcd/ca.crt
    - --snapshot-count=10000
    - --trusted-ca-file=/etc/kubernetes/pki/etcd/ca.crt
    - --initial-cluster-state=existing
    image: k8s.gcr.io/etcd:3.2.24
    imagePullPolicy: IfNotPresent
    livenessProbe:
      exec:
        command:
        - /bin/sh
        - -ec
        - ETCDCTL_API=3 etcdctl --endpoints=https://10.0.0.1:2379,https://10.0.0.2:2379,https://10.0.0.3:2379 --cacert=/etc/kubernetes/pki/etcd/ca.crt --cert=/etc/kubernetes/pki/etcd/healthcheck-client.crt --key=/etc/kubernetes/pki/etcd/healthcheck-client.key get foo
...

replacing a failed etcd member

[!TIP] consider a three-member etcd cluster. Let the URLs be:
member1=http://10.0.0.1
member2=http://10.0.0.2
member3=http://10.0.0.3 When member1 fails, replace it with member4=http://10.0.0.4.

get member id of failed member

$ etcdctl --endpoints=http://10.0.0.2,http://10.0.0.3 member list

8211f1d0f64f3269, started, member1, http://10.0.0.1:2380, http://10.0.0.1:2379
91bc3c398fb3c146, started, member2, http://10.0.0.2:2380, http://10.0.0.2:2379
fd422379fda50e48, started, member3, http://10.0.0.3:2380, http://10.0.0.3:2379

remove failed member

$ etcdctl member remove 8211f1d0f64f3269
Removed member 8211f1d0f64f3269 from cluster

add new members

$ etcdctl member add member4 --peer-urls=http://10.0.0.4:2380
Member 2be1eb8f84b7f63e added to cluster ef37ad9dc622a7c4

start new member with IP

$ export ETCD_NAME="member4"
$ export ETCD_INITIAL_CLUSTER="member2=http://10.0.0.2:2380,member3=http://10.0.0.3:2380,member4=http://10.0.0.4:2380"
$ export ETCD_INITIAL_CLUSTER_STATE=existing
$ etcd [flags]

additional options
[!TIP]
- Update the --etcd-servers flag for the Kubernetes API servers to make Kubernetes aware of the configuration changes, then restart the Kubernetes API servers.
- Update the load balancer configuration if a load balancer is used in the deployment.

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Last updated 1 year ago

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