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Percona XtraDB Cluster images
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Percona XtraDB Cluster docker image

The docker image is available right now at perconalab/percona-xtradb-cluster.
The image supports work in Docker Network, including overlay networks,
so that you can install Percona XtraDB Cluster nodes on different boxes.
There is an initial support for the etcd discovery service.

Basic usage

For an example, see the start_node.sh script.

The CLUSTER_NAME environment variable should be set, and the easiest to do it is:
export CLUSTER_NAME=cluster1

The script will try to create an overlay network ${CLUSTER_NAME}_net.
If you want to have a bridge network or network with a specific parameter,
create it in advance.
For example:
docker network create -d bridge ${CLUSTER_NAME}_net

The Docker image accepts the following parameters:

  • One of MYSQL_ROOT_PASSWORD, MYSQL_ALLOW_EMPTY_PASSWORD or MYSQL_RANDOM_ROOT_PASSWORD must be defined
  • The image will create the user xtrabackup@localhost for the XtraBackup SST method. If you want to use a password for the xtrabackup user, set XTRABACKUP_PASSWORD.
  • If you want to use the discovery service (right now only etcd is supported), set the address to DISCOVERY_SERVICE. The image will automatically find a running cluser by CLUSTER_NAME and join to the existing cluster (or start a new one).
  • If you want to start without the discovery service, use the CLUSTER_JOIN variable. Empty variables will start a new cluster, To join an existing cluster, set CLUSTER_JOIN to the list of IP addresses running cluster nodes.

Discovery service

The cluster will try to register itself in the discovery service, so that new nodes or ProxySQL can easily find running nodes.

Assuming you have the variable ETCD_HOST set to IP:PORT of the running etcd (e.g., export ETCD_HOST=10.20.2.4:2379), you can explore the current settings by using
curl http://$ETCD_HOST/v2/keys/pxc-cluster/$CLUSTER_NAME/?recursive=true | jq.

Example output:

{
  "action": "get",
  "node": {
    "key": "/pxc-cluster/cluster4",
    "dir": true,
    "nodes": [
      {
        "key": "/pxc-cluster/cluster4/10.0.5.2",
        "dir": true,
        "nodes": [
          {
            "key": "/pxc-cluster/cluster4/10.0.5.2/ipaddr",
            "value": "10.0.5.2",
            "modifiedIndex": 19600,
            "createdIndex": 19600
          },
          {
            "key": "/pxc-cluster/cluster4/10.0.5.2/hostname",
            "value": "2af0a75ce0cb",
            "modifiedIndex": 19601,
            "createdIndex": 19601
          }
        ],
        "modifiedIndex": 19600,
        "createdIndex": 19600
      },
      {
        "key": "/pxc-cluster/cluster4/10.0.5.3",
        "dir": true,
        "nodes": [
          {
            "key": "/pxc-cluster/cluster4/10.0.5.3/ipaddr",
            "value": "10.0.5.3",
            "modifiedIndex": 26420,
            "createdIndex": 26420
          },
          {
            "key": "/pxc-cluster/cluster4/10.0.5.3/hostname",
            "value": "cfb29833f1d6",
            "modifiedIndex": 26421,
            "createdIndex": 26421
          }
        ],
        "modifiedIndex": 26420,
        "createdIndex": 26420
      }
    ],
    "modifiedIndex": 19600,
    "createdIndex": 19600
  }
}

Currently there is no automatic cleanup for the discovery service registry. You can remove all entries using
curl http://10.20.2.4:2379/v2/keys/pxc-cluster/$CLUSTER_NAME?recursive=true -XDELETE.

Starting a discovery service

For the full documentation, please check https://coreos.com/etcd/docs/latest/docker_guide.html.

A simple script to start 1-node etcd (assuming ETCD_HOST variable is defined) is:

ETCD_HOST=${ETCD_HOST:-10.20.2.4:2379}
docker run -d -v /usr/share/ca-certificates/:/etc/ssl/certs -p 4001:4001 -p 2380:2380 -p 2379:2379 \
 --name etcd quay.io/coreos/etcd \
 -name etcd0 \
 -advertise-client-urls http://${ETCD_HOST}:2379,http://${ETCD_HOST}:4001 \
 -listen-client-urls http://0.0.0.0:2379,http://0.0.0.0:4001 \
 -initial-advertise-peer-urls http://${ETCD_HOST}:2380 \
 -listen-peer-urls http://0.0.0.0:2380 \
 -initial-cluster-token etcd-cluster-1 \
 -initial-cluster etcd0=http://${ETCD_HOST}:2380 \
 -initial-cluster-state new

Running a Docker overlay network

The following link is a great introduction with easy steps on how to run a Docker overlay network: http://chunqi.li/2015/11/09/docker-multi-host-networking/

Running with ProxySQL

The ProxySQL image https://hub.docker.com/r/perconalab/proxysql/
provides an integration with Percona XtraDB Cluster and discovery service.

You can start proxysql image by

docker run -d -p 3306:3306 -p 6032:6032 --net=$NETWORK_NAME --name=${CLUSTER_NAME}_proxysql \
        -e CLUSTER_NAME=$CLUSTER_NAME \
        -e ETCD_HOST=$ETCD_HOST \
        -e MYSQL_ROOT_PASSWORD=Theistareyk \
        -e MYSQL_PROXY_USER=proxyuser \
        -e MYSQL_PROXY_PASSWORD=s3cret \
        perconalab/proxysql

where MYSQL_ROOT_PASSWORD is the root password for the MySQL nodes. The password is needed to register the proxy user. The user MYSQL_PROXY_USER with password MYSQL_PROXY_PASSWORD will be registered on all Percona XtraDB Cluster nodes.

Running docker exec -it ${CLUSTER_NAME}_proxysql add_cluster_nodes.sh will register all nodes in the ProxySQL.

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