Today we will setup MySQL on Docker Swarm backed with a Replicated GlusterFS volume that will enable us with data persistence.
I recommend running any database service outside the swarm, but since we are using this for testing purposes, we will run MySQL inside the swarm
Pre-Requirements:
- Docker Swarm
- Replicated GlusterFS Volume
Create the Overlay Network:
If you don't already have a overlay network, create one:
$ docker network create --driver=overlay docknet
Create the Service:
Create the MySQL Service and specify the data directory to the path that is mounted of GlusterFS:
$ docker service create \
--name mysql \
--network docknet \
--mount "type=bind,source=/mnt/volumes/mysql/data,target=/var/lib/mysql,readonly=false" \
--env MYSQL_ROOT_PASSWORD=pass \
--replicas 1 \
hypriot/rpi-mysql
After some time, you should see the following output:
$ docker service ls
ID NAME MODE REPLICAS IMAGE PORTS
m6f4tn2ccubq mysql replicated 1/1 hypriot/rpi-mysql:latest
Create a MySQL Client:
Let's create a service within the same network that will act as a MySQL Client to interact with our MySQL Service:
$ docker service create --name client --network docknet --replicas 1 arm32v6/alpine ping 127.0.0.1
Listing the service, to determine if the service is in the desired replicated state:
$ docker service ls
ID NAME MODE REPLICAS IMAGE PORTS
m6f4tn2ccubq mysql replicated 1/1 hypriot/rpi-mysql:latest
zq3pmbnun2fj client replicated 1/1 arm32v6/alpine:latest
Having a look to see on which node the replica reside:
pi@rpi-01:~ $ docker service ps client
ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS
melrgjjxcac9 client.1 arm32v6/alpine:latest rpi-02 Running Running 15 seconds ago
As we can see the container is running on node rpi-02, let's ssh to the node to exec into the container:
pi@rpi-01:~ $ ssh rpi-02
Now that we are on the node, lets exec into the container:
pi@rpi-02:~ $ docker exec -it client.1.melrgjjxcac9gor2436cceo7r sh
We would like to connect to mysql, and as we created a container that is associated to the same network, we will use that container to connect to the mysql service.
In order to do that, we need to install the mysql-client, first update the repository index:
$ apk update
fetch http://dl-cdn.alpinelinux.org/alpine/v3.6/main/armhf/APKINDEX.tar.gz
fetch http://dl-cdn.alpinelinux.org/alpine/v3.6/community/armhf/APKINDEX.tar.gz
v3.6.2-80-gd6beefe139 [http://dl-cdn.alpinelinux.org/alpine/v3.6/main]
v3.6.2-78-gc30bfa742f [http://dl-cdn.alpinelinux.org/alpine/v3.6/community]
OK: 8274 distinct packages available
Then install the mysql client:
$ apk add mysql-client
(1/8) Installing mariadb-common (10.1.22-r1)
(2/8) Installing ncurses-terminfo-base (6.0-r8)
(3/8) Installing ncurses-terminfo (6.0-r8)
(4/8) Installing ncurses-libs (6.0-r8)
(5/8) Installing libgcc (6.3.0-r4)
(6/8) Installing libstdc++ (6.3.0-r4)
(7/8) Installing mariadb-client (10.1.22-r1)
(8/8) Installing mysql-client (10.1.22-r1)
Executing busybox-1.26.2-r5.trigger
OK: 35 MiB in 19 packages
Finally connect to the MySQL Server:
$ mysql -h mysql -u root -ppass
Welcome to the MariaDB monitor. Commands end with ; or \g.
Your MySQL connection id is 1
Server version: 5.5.54-0+deb7u1 (Debian)
Copyright (c) 2000, 2016, Oracle, MariaDB Corporation Ab and others.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
MySQL [(none)]> exit
Bye