There’s been a lot of talk about Docker for running processes in isolated userspace (or the cloud for that matter) lately. Virtualization is a great way to compartmentalise applications and processes however the overhead of virtualization isn’t always worth it – in fact, without directly attached storage IO degradation can seriously impact performance. The solution? Perhaps Docker… With its easy to use CLI as well as the lightweight implementation of cgroups and kernel namespaces.
Without further ado, I present a step-bystep guide on how to build a MariaDB 5.5 Galera Cluster on Ubuntu 14.04. The same guide can probably be applied for MariaDB versions 10+ however I’ve stuck with 5.5 since the latest version of MariaDB Galera Cluster is still in beta.
So we start off with modifying the “ufw” firewall policy to accept forwarded packets and perform a “ufw” service restart for good measure:
root@workstation:~# vi /etc/default/ufw
DEFAULT_FORWARD_POLICY="ACCEPT"
root@workstation:~# service ufw restart
ufw stop/waiting
ufw start/running
I’m assuming you already have docker installed – this is available as a package within the Ubuntu repositories and also available in the Docker repositories (see https://docs.docker.com/installation/ubuntulinux/). You’ll also need to have LXC installed (“apt-get install lxc” should suffice) in order to attach to the Linux Containers / Docker Images.
The next step is pulling the Docker / Ubuntu repository in order to customize an image for our purposes
root@workstation:~# docker pull ubuntu
Pulling repository ubuntu
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After the download is complete, we can check the Ubuntu images available for customization with the following command:
root@workstation:~# docker images
REPOSITORY TAG IMAGE ID CREATED VIRTUAL SIZE
ubuntu 14.04.1 c4ff7513909d 12 days ago 225.4 MB
ubuntu trusty c4ff7513909d 12 days ago 225.4 MB
ubuntu 14.04 c4ff7513909d 12 days ago 225.4 MB
ubuntu latest c4ff7513909d 12 days ago 225.4 MB
ubuntu utopic 75204fdb260b 12 days ago 230.1 MB
ubuntu 14.10 75204fdb260b 12 days ago 230.1 MB
ubuntu precise 822a01ae9a15 12 days ago 108.1 MB
ubuntu 12.04 822a01ae9a15 12 days ago 108.1 MB
ubuntu 12.04.5 822a01ae9a15 12 days ago 108.1 MB
ubuntu 12.10 c5881f11ded9 9 weeks ago 172.2 MB
ubuntu quantal c5881f11ded9 9 weeks ago 172.2 MB
ubuntu 13.04 463ff6be4238 9 weeks ago 169.4 MB
ubuntu raring 463ff6be4238 9 weeks ago 169.4 MB
ubuntu 13.10 195eb90b5349 9 weeks ago 184.7 MB
ubuntu saucy 195eb90b5349 9 weeks ago 184.7 MB
ubuntu lucid 3db9c44f4520 4 months ago 183 MB
ubuntu 10.04 3db9c44f4520 4 months ago 183 MB
Now that we’ve downloaded our images lets create a custom Dockerfile for our customized MariaDB / Galera Docker image, I’ve added a brief description for each line of the file:
root@workstation:~# vi Dockerfile
# # MariaDB Galera 5.5.39/Ubuntu 14.04 64bit
FROM ubuntu:14.04
MAINTAINER Pythian Nikolaos Vyzas <vyzas@pythian.com>
# add the universe repo
RUN echo "deb https://archive.ubuntu.com/ubuntu trusty main universe" > /etc/apt/sources.list
# update apt
RUN apt-get -q -y update
# install software-properties-common for key management
RUN apt-get -q -y install software-properties-common
# add the key for Mariadb Ubuntu repos
RUN apt-key adv --recv-keys --keyserver hkp://keyserver.ubuntu.com:80 0xcbcb082a1bb943db
# add the MariaDB repository for 5.5
RUN add-apt-repository 'deb https://ftp.cc.uoc.gr/mirrors/mariadb/repo/5.5/ubuntu trusty main'
# update apt again
RUN apt-get -q -y update
# configure the default root password during installation
RUN echo mariadb-galera-server-5.5 mysql-server/root_password password root | debconf-set-selections
# confirm the password (as in the usual installation)
RUN echo mariadb-galera-server-5.5 mysql-server/root_password_again password root | debconf-set-selections
# install the necessary packages
RUN LC_ALL=en_US.utf8 DEBIAN_FRONTEND=noninteractive apt-get -o Dpkg::Options::='--force-confnew' -qqy install mariadb-galera-server galera mariadb-client
# upload the locally created my.cnf (obviously this can go into the default MariaDB path
ADD ./my.cnf /etc/mysql/my.cnf
# startup the service - this will fail since the nodes haven't been configured on first boot
RUN service mysql restart
# open the ports required to connect to MySQL and for Galera SST / IST operations
EXPOSE 3306 4444 4567 4568
We'll also need our base configuration for MariaDB, I've included the base configuration variable for Galera - obviously there are more however these are good enough for starting up the service:
root@workstation:~# vi my.cnf
[mysqld]
wsrep_provider=/usr/lib/galera/libgalera_smm.so
wsrep_cluster_address=gcomm://
wsrep_sst_method=rsync
wsrep_cluster_name=galera_cluster
binlog_format=ROW
default_storage_engine=InnoDB
innodb_autoinc_lock_mode=2
innodb_locks_unsafe_for_binlog=1
So far so good, we have Docker installed and our Dockerfile as well as our “my.cnf” file ready to go. Now its time to build our Docker image, check that the image exists and startup 3x separate Docker images for each of our Galera nodes:
root@workstation:~# docker build -t ubuntu_trusty/mariadb-galera .
root@workstation:~# docker images |grep mariadb-galera
ubuntu_trusty/mariadb-galera latest afff3aaa9dfb About a minute ago 412.5 MB
docker run --name mariadb1 -i -t -d ubuntu_trusty/mariadb-galera /bin/bash
docker run --name mariadb2 -i -t -d ubuntu_trusty/mariadb-galera /bin/bash
docker run --name mariadb3 -i -t -d ubuntu_trusty/mariadb-galera /bin/bash
We’ve started up our Docker images, now lets verify that they are in fact up and retrieve the process information we need to connect. We’ll need two pieces of information, the IP-Address and the Docker image name which can be received using the combination the the “docker ps” and the “docker inspect” commands:
}]root@workstation:~# docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
b51e74933ece ubuntu_trusty/mariadb-galera:latest /bin/bash About an hour ago Up About an hour 3306/tcp, 4444/tcp, 4567/tcp, 4568/tcp mariadb3
03109c7018c0 ubuntu_trusty/mariadb-galera:latest /bin/bash About an hour ago Up About an hour 3306/tcp, 4444/tcp, 4567/tcp, 4568/tcp mariadb2
1db2a9a520f8 ubuntu_trusty/mariadb-galera:latest /bin/bash About an hour ago Up About an hour 3306/tcp, 4444/tcp, 4567/tcp, 4568/tcp mariadb1
root@workstation:~# docker ps |cut -d' ' -f1 |grep -v CONTAINER | xargs docker inspect |egrep '"ID"|IPAddress'
"ID": "b51e74933ece2f3f457ec87c3a4e7b649149e9cff2a4705bef2a070f7adbafb0",
"IPAddress": "172.17.0.3",
"ID": "03109c7018c03ddd8448746437346f080a976a74c3fc3d15f0191799ba5aae74",
"IPAddress": "172.17.0.4",
"ID": "1db2a9a520f85d2cef6e5b387fa7912890ab69fc0918796c1fae9c1dd050078f",
"IPAddress": "172.17.0.2",
Time to use lxc-attach to connect to our Docker images using the Docker image name, add the mounts to “/etc/mtab” to keep them MariaDB friendly and customize the “gcomm://” address as we would for a usual Galera configuration (the Docker image name is a generated when the instance fires up so make sure to use your own instance name in the following commands):
root@workstation:~# lxc-attach --name b51e74933ece2f3f457ec87c3a4e7b649149e9cff2a4705bef2a070f7adbafb0
root@b51e74933ece:~# cat /proc/mounts > /etc/mtab
root@b51e74933ece:~# service mysql restart
* Starting MariaDB database mysqld [ OK ]
* Checking for corrupt, not cleanly closed and upgrade needing tables.
root@b51e74933ece:~# vi /etc/mysql/my.cnf
#wsrep_cluster_address=gcomm://
wsrep_cluster_address=gcomm://172.17.0.2,172.17.0.3,172.17.0.4
root@b51e74933ece:~# exit
exit
root@workstation:~# lxc-attach --name 03109c7018c03ddd8448746437346f080a976a74c3fc3d15f0191799ba5aae74
root@03109c7018c0:~# cat /proc/mounts > /etc/mtab
root@03109c7018c0:~# vi /etc/mysql/my.cnf
#wsrep_cluster_address=gcomm://
wsrep_cluster_address=gcomm://172.17.0.2,172.17.0.3,172.17.0.4
root@03109c7018c0:~# service mysql start
* Starting MariaDB database server mysqld [ OK ]
* Checking for corrupt, not cleanly closed and upgrade needing tables.
root@03109c7018c0:~# mysql -uroot -proot
Welcome to the MariaDB monitor. Commands end with ; or \g.
Your MariaDB connection id is 30
Server version: 5.5.39-MariaDB-1~trusty-wsrep mariadb.org binary distribution, wsrep_25.10.r4014
Copyright (c) 2000, 2014, Oracle, Monty Program Ab and others.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
MariaDB [(none)]> show status like 'wsrep_cluster%';
+--------------------------+--------------------------------------+
| Variable_name | Value |
+--------------------------+--------------------------------------+
| wsrep_cluster_conf_id | 2 |
| wsrep_cluster_size | 2 |
| wsrep_cluster_state_uuid | 42bc375b-2bc0-11e4-851c-1a7627c0624c |
| wsrep_cluster_status | Primary |
+--------------------------+--------------------------------------+
4 rows in set (0.00 sec_
MariaDB [(none)]> exit
Bye
root@03109c7018c0:~# exit
exit
root@workstation:~# lxc-attach --name 1db2a9a520f85d2cef6e5b387fa7912890ab69fc0918796c1fae9c1dd050078f
root@1db2a9a520f8:~# cat /proc/mounts > /etc/mtab
root@1db2a9a520f8:~# vi /etc/mysql/my.cnf
root@1db2a9a520f8:~# service mysql start
* Starting MariaDB database server mysqld [ OK ]
root@1db2a9a520f8:~# mysql -uroot -proot
Welcome to the MariaDB monitor. Commands end with ; or \g.
Your MariaDB connection id is 34
Server version: 5.5.39-MariaDB-1~trusty-wsrep mariadb.org binary distribution, wsrep_25.10.r4014
Copyright (c) 2000, 2014, Oracle, Monty Program Ab and others.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
MariaDB [(none)]> show status like 'wsrep_cluster%';
+--------------------------+--------------------------------------+
| Variable_name | Value |
+--------------------------+--------------------------------------+
| wsrep_cluster_conf_id | 3 |
| wsrep_cluster_size | 3 |
| wsrep_cluster_state_uuid | 42bc375b-2bc0-11e4-851c-1a7627c0624c |
| wsrep_cluster_status | Primary |
+--------------------------+--------------------------------------+
4 rows in set (0.00 sec)
MariaDB [(none)]> exit
Bye
root@1db2a9a520f8:~# exit
exit
Now be honest… Wasn’t that easier than creating multiple virtual machines and configuring the OS for each?
Enjoy your new MariaDB Galera Cluster and happy Dockering!
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