Version 2 Dockerized Automated MariaDB Galera Cluster
Version 2 is the advanced branch and is featured on DockerHub as latest from now on.
Old version 1.0 can be found here: https://github.com/toughIQ/docker-mariadb-cluster/tree/v1.
To get V1.0 Docker images, just docker pull toughiq/mariadb-cluster:1.0
The idea of this project is to create an automated and fully ephemeral MariaDB Galera cluster. No static bindings, no persistent volumes. Like a disk RAID the data gets replicated across the cluster. If one node fails, another node will be brought up and the data will be initialized.
Consider this a POC and not a production ready system!
Built for use with Docker 1.12.1+ in Swarm Mode
See Issues for known problems and Wiki for notes and ideas.
Swarm Master:
docker swarm init
Additional Swarm Node(s):
docker swarm join <MasterNodeIP>:2377 + join-tokens shown at swarm init
To get the tokens at a later time, run docker swarm join-token (manager|worker)
docker network create -d overlay mydbnet
At first we start with a new service, which is set to --replicas=1 to turn this instance into a bootstrapping node.
If there is just one service task running within the cluster, this instance automatically starts with bootstrapping enabled.
docker service create --name dbcluster \
--network mydbnet \
--replicas=1 \
--env DB_SERVICE_NAME=dbcluster \
toughiq/mariadb-cluster
Note: the service name provided by --name has to match the environment variable DB_SERVICE_NAME set with --env DB_SERVICE_NAME.
Of course there are the default MariaDB options to define a root password, create a database, create a user and set a password for this user. Example:
docker service create --name dbcluster \
--network mydbnet \
--replicas=1 \
--env DB_SERVICE_NAME=dbcluster \
--env MYSQL_ROOT_PASSWORD=rootpass \
--env MYSQL_DATABASE=mydb \
--env MYSQL_USER=mydbuser \
--env MYSQL_PASSWORD=mydbpass \
toughiq/mariadb-cluster
Just after the first service instance/task is running with we are good to scale out.
Check service with docker service ps dbcluster. The result should look like this, with CURRENT STATE telling something like Running.
ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR
7c81muy053eoc28p5wrap2uzn dbcluster.1 toughiq/mariadb-cluster node01 Running Running 41 seconds ago
Lets scale out now:
docker service scale dbcluster=3
This additional 2 nodes start will come up in "cluster join"-mode. Lets check again: docker service ps dbcluster
ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR
7c81muy053eoc28p5wrap2uzn dbcluster.1 toughiq/mariadb-cluster node01 Running Running 6 minutes ago
8ht037ka0j4g6lnhc194pxqfn dbcluster.2 toughiq/mariadb-cluster node02 Running Running about a minute ago
bgk07betq9pwgkgpd3eoozu6u dbcluster.3 toughiq/mariadb-cluster node03 Running Running about a minute ago
There is no absolute need for a MaxScale Proxy service with this Docker Swarm enabled DB cluster, since Swarm provides a loadbalancer. So it would be possible to connect to the cluster by using the loadbalancer DNS name, which is in our case dbcluster. Its the same name, which is provided at startup by --name.
But MaxScale provides some additional features regarding loadbalancing database traffic. And its an easy way to get information on the status of the cluster.
Details on this MaxScale image can be found here: https://github.com/toughIQ/docker-maxscale
docker service create --name maxscale \
--network mydbnet \
--env DB_SERVICE_NAME=dbcluster \
--env ENABLE_ROOT_USER=1 \
--publish 3306:3306 \
toughiq/maxscale
To disable root access to the database via MaxScale just set --env ENABLE_ROOT_USER=0 or remove this line at all.
Root access is disabled by default.
Execute the following command. Just use autocompletion to get the SLOT and ID.
docker exec -it maxscale.<SLOT>.<ID> maxadmin -pmariadb list servers
The result should report the cluster up and running:
-------------------+-----------------+-------+-------------+--------------------
Server | Address | Port | Connections | Status
-------------------+-----------------+-------+-------------+--------------------
10.0.0.3 | 10.0.0.3 | 3306 | 0 | Slave, Synced, Running
10.0.0.4 | 10.0.0.4 | 3306 | 0 | Slave, Synced, Running
10.0.0.5 | 10.0.0.5 | 3306 | 0 | Master, Synced, Running
-------------------+-----------------+-------+-------------+--------------------