How can I restore etcd cluster from snapshot in docker image on CoreOS?

3
votes

I have a Kubernetes cluster (v1.5.6) with 3 nodes etcd cluster (etcd version 3.1.5) on vmware. This etcd nodes are running in three docker containers(on three hosts) on coreos on vmware.

I try to backup etcd with the following solution:

docker run --rm --net=host -v /tmp:/etcd_backup -e ETCDCTL_API=3 quay.io/coreos/etcd:v3.1.5 etcdctl --endpoints=[1.1.1.1:2379,2.2.2.2:2379,3.3.3.3:2379] snapshot save etcd_backup/snapshot.db

The backup has been completed succesfully.

I want to create this kubernetes cluster from zero in another vmware environment, but I need to restore etcd from snapshot for this.

So far, I have not found the right solution that works with etcd in docker containers.

I try to restore with the following method, but unfortunately I did not succeed.

First, I created a new etcd node after I run the following command:

docker run --rm --net=host -v /tmp/etcd_bak:/etcd_backup -e ETCDCTL_API=3 registry:5000/quay.io/coreos/etcd:v3.1.5 etcdctl snapshot restore etcd_backup/snapshot.db --name etcd0 --initial-cluster etcd0=http://etcd0:2380,etcd1=http://etcd1:2380,etcd2=http://etcd2:2380 --initial-cluster-token etcd-cluster-1 --initial-advertise-peer-urls http://etcd0:2380

Result:

2018-06-04 09:25:52.314747 I | etcdserver/membership: added member 7ff5c9c6942f82e [http://etcd0:2380] to cluster 5d1b637f4b7740d5
2018-06-04 09:25:52.314940 I | etcdserver/membership: added member 91b417e7701c2eeb [http://etcd2:2380] to cluster 5d1b637f4b7740d5
2018-06-04 09:25:52.315096 I | etcdserver/membership: added member faeb78734ee4a93d [http://etcd1:2380] to cluster 5d1b637f4b7740d5

Unfortunately, nothing happens.

What is the good solution to restore the etcd backup?

How do I create an empty etcd cluster/node and how should I restore the snapshot?

2
dockerkubernetescoreosetcd

2 Answers

4
votes

according to the Etcd Disaster Recovery document, you need restore all three etcd nodes from snapshot with commands like yours, then run three node with commands like this:

etcd \
  --name m1 \
  --listen-client-urls http://host1:2379 \
  --advertise-client-urls http://host1:2379 \
  --listen-peer-urls http://host1:2380 &

Also, you can extract etcdctl from the image, like this:

docker run --rm -v /opt/bin:/opt/bin registry:5000/quay.io/coreos/etcd:v3.1.5 cp /usr/local/bin/etcdctl /opt/bin

Then use etcdctl to restore snapshot:

# ETCDCTL_API=3 ./etcdctl snapshot restore snapshot.db \
  --name m1 \
  --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 \
  --data-dir /var/lib/etcd

This will restore snapshot to the /var/lib/etcd directory. Then start etcd with docker, don't forget mount /var/lib/etcd into your container, and specify --data-dir to it .

3
votes

Ectd in kubernetes is running in Docker containers, here was what I did to recovery the cluster:

  • retrieve Etcd cluster metedata

    docker inspect etcd1

    you'd got something like below:

    "Binds": [
    "/etc/ssl/certs:/etc/ssl/certs:ro",
    "/etc/ssl/etcd/ssl:/etc/ssl/etcd/ssl:ro",
    "/var/lib/etcd:/var/lib/etcd:rw"
],
...
"Env": [
    "ETCD_DATA_DIR=/var/lib/etcd",
    "ETCD_ADVERTISE_CLIENT_URLS=https://172.16.60.1:2379",
    "ETCD_INITIAL_ADVERTISE_PEER_URLS=https://172.16.60.1:2380",
    "ETCD_INITIAL_CLUSTER_STATE=existing",
    "ETCD_METRICS=basic",
    "ETCD_LISTEN_CLIENT_URLS=https://172.16.60.1:2379,https://127.0.0.1:2379",
    "ETCD_ELECTION_TIMEOUT=5000",
    "ETCD_HEARTBEAT_INTERVAL=250",
    "ETCD_INITIAL_CLUSTER_TOKEN=k8s_etcd",
    "ETCD_LISTEN_PEER_URLS=https://172.16.60.1:2380",
    "ETCD_NAME=etcd1",
    "ETCD_PROXY=off",
    "ETCD_INITIAL_CLUSTER=etcd1=https://172.16.60.1:2380,etcd2=https://172.16.60.2:2380,etcd3=https://172.16.60.2:2380",
    "ETCD_AUTO_COMPACTION_RETENTION=8",
    "ETCD_TRUSTED_CA_FILE=/etc/ssl/etcd/ssl/ca.pem",
    "ETCD_CERT_FILE=/etc/ssl/etcd/ssl/member-node01.pem",
    "ETCD_KEY_FILE=/etc/ssl/etcd/ssl/member-node01-key.pem",
    "ETCD_PEER_TRUSTED_CA_FILE=/etc/ssl/etcd/ssl/ca.pem",
    "ETCD_PEER_CERT_FILE=/etc/ssl/etcd/ssl/member-node01.pem",
    "ETCD_PEER_KEY_FILE=/etc/ssl/etcd/ssl/member-node01-key.pem",
    "ETCD_PEER_CLIENT_CERT_AUTH=true",
    "PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
],
"Cmd": [
    "/usr/local/bin/etcd"
],

  • copy etcd snapshotdb to other etcd nodes

    scp snapshotdb_20180913 node02:/root/  
scp snapshotdb_20180913 node03:/root/

  • rebuild a new cluster with original info

    # etcd1
docker stop etcd1
rm -rf /var/lib/etcd

ETCDCTL_API=3 etcdctl snapshot restore snapshotdb_20180913 \
  --cacert /etc/ssl/etcd/ssl/ca.pem \
  --cert /etc/ssl/etcd/ssl/member-node01.pem \
  --key /etc/ssl/etcd/ssl/member-node01-key.pem \
  --name etcd1 \
  --initial-cluster etcd1=https://node01:2380,etcd2=https://node02:2380,etcd3=https://node03:2380 \
  --initial-cluster-token k8s_etcd \
  --initial-advertise-peer-urls https://node01:2380 \
  --data-dir /var/lib/etcd

# etcd2
docker stop etcd2
rm -rf /var/lib/etcd

ETCDCTL_API=3 etcdctl snapshot restore snapshotdb_20180913 \
  --cacert /etc/ssl/etcd/ssl/ca.pem \
  --cert /etc/ssl/etcd/ssl/member-node02.pem \
  --key /etc/ssl/etcd/ssl/member-node02-key.pem \
  --name etcd2 \
  --initial-cluster etcd1=https://node01:2380,etcd2=https://node02:2380,etcd3=https://node03:2380 \
  --initial-cluster-token k8s_etcd \
  --initial-advertise-peer-urls https://node02:2380 \
  --data-dir /var/lib/etcd

# etcd3
docker stop etcd3
rm -rf /var/lib/etcd

ETCDCTL_API=3 etcdctl snapshot restore snapshotdb_20180913 \
  --cacert /etc/ssl/etcd/ssl/ca.pem \
  --cert /etc/ssl/etcd/ssl/member-node03.pem \
  --key /etc/ssl/etcd/ssl/member-node03-key.pem \
  --name etcd3 \
  --initial-cluster etcd1=https://node01:2380,etcd2=https://node02:2380,etcd3=https://node03:2380 \
  --initial-cluster-token k8s_etcd \
  --initial-advertise-peer-urls https://node03:2380 \
  --data-dir /var/lib/etcd

  • start containers and check cluster status

    cd /etc/ssl/etcd/ssl
etcdctl \
  --endpoints=https://node01:2379 \
  --ca-file=./ca.pem \
  --cert-file=./member-node01.pem \
  --key-file=./member-node01-key.pem \
  member list