Auto Clustering/Replicating Percona Database
How does it work ?
There are two images in this project, the first contains Percona and the Galera replication tools, the second contains Maxscale (a MySQL load balancer).
When run with access to a service discovery tool (
etcd by default) it is
able discover other running databases and set up a replication relationship.
By default it uses Glider Labs'
registrator to perform the service
registry, but can access
etcd directly if that is your preference.
Inside the container
runit manages three processes:
Used to watch the
etcd endpoint and rewrite config files with any changes.
Watches availability of the application ( percona or maxscale ) and kills runit (thus the container) when it fails.
percona / maxscale
Runs the main process for the container, either Percona or Maxscale depending on which image is running.
See factorish for a detailed description of the factorish toolset.
If you want to run this outside of the tech demo see the
and/or start the tech demo first and view the
file in any of the
registry is hosted in a path mapped in from the host computer and
therefore is shared amongst the
coreos nodes. This means that any
images pushed to it from one host are immediately avaliable to all the
This allows for some intelligent image pulling/building to ensure that
only a single node has to do the heavy lifting. See the
file for the scripts that allow this sharing of work.
maxscale images are built from scratch automatically and started as the
coreos nodes come online. Thanks to the
registry they will survive a
vagrant destroy which means subsequent
vagrant up will be
Running in CoreOS with etcd/registrator discovery
In order to use the tech demo simply run the following:
$ git clone https://github.com/paulczar/docker-percona_galera.git $ cd docker-percona_galera $ vagrant up
Once Vagrant has brought up your three nodes you want to log in and watch the progress of the build using one of the provided helper functions:
$ vagrant ssh core-01 $ journal_database
This make take a few minutes if its the first time you've run this and the images aren't cached in the registry. If you get bored you can also check out
journal_registrator and watch them get pulled down and run. It is also possible a different host will be elected to do the build, in which case you'll see it show as waiting for that host before it proceeds.
Once the database is online ( you'll see percona start and replication collect in the
journal_database output ) you can connect to Maxscale via the helper function
$ mysql mysql> select @@hostname; +--------------+ | @@hostname | +--------------+ | a7575fd684eb | +--------------+
the maxscale LB can take a while to find the service to loadbalance, and can also sometimes just fail. I haven't worked out why yet.
or by connecting to the shell of the database container on the current host:
$ database root@ecfd272af45e:/app# mysql mysql> select @@hostname; +--------------+ | @@hostname | +--------------+ | ecfd272af45e | +--------------+
notice the returned hostname is not the same in both queries, this is because the first was loadbalanced to the database on a different container
Each container started at boot has the following helper functions created
/etc/profile.d/functions.sh and autoloaded by the shell.
(examples shown below for
database- get shell in container.
kill_database- kills the container, equivalent to
docker rm -f database
build_database- rebuilds the image
push_database- pushs the image to registry
log_database- connect to the docker log stream for that container
journal_database- connect to the systemd journal for that container
They become very useful when combined:
$ build_database && push_database $ kill_database && run_database && log_database
There is also the
mysql function which will connect you via the local proxy to a percona server and a
cleanup function which deletes the
Finally in the git repo is a
clean_registry script which when run on the host will remove all images from the registry filesystem which is useful if you want to do a full rebuild from scratch.
Running without service discovery:
HOST to be the IP address of the server.
$ export HOST=172.17.8.101 $ docker run --detach \ --name database01 \ -e BOOTSTRAP=1 -e DEBUG=1 \ -e MYSQL_PASS=password -e REP_PASS=replicate \ -e HOST=$HOST -e SERVICE_DISCOVERY=env \ -p $HOST:3306:3306 \ -p $HOST:4444:4444 \ -p $HOST:4567:4567 \ -p $HOST:4568:4568 \ paulczar/percona-galera
HOST to be the IP address of the server, change
CLUSTER_MEMBERS to be the IP of the first server.
$ export HOST=172.17.8.102 docker run -ti --rm \ --name database02 \ -e DEBUG=1 \ -e MYSQL_PASS=password -e REP_PASS=replicate \ -e CLUSTER_MEMBERS=172.17.8.101 \ -e HOST=$HOST -e SERVICE_DISCOVERY=env \ -p $HOST:3306:3306 \ -p $HOST:4444:4444 \ -p $HOST:4567:4567 \ -p $HOST:4568:4568 \ paulczar/percona-galera bash
Run in Rackspace's Carina Service:
Signup for carina and create a 3 node cluster. Download and source the carina config files and get the carina binary as well.
note this will leave the mysql and galera ports open to the whole of the service-net network
we need to get the servicenet IP address of each node:
$ docker info Containers: 7 Images: 6 Engine Version: Role: primary Strategy: spread Filters: health, port, dependency, affinity, constraint Nodes: 3 bf76bea4-47ef-43ac-a7ae-67a6e6db15bf-n1: 22.214.171.124:42376 └ Containers: 3 └ Reserved CPUs: 0 / 12 └ Reserved Memory: 0 B / 4.2 GiB └ Labels: executiondriver=native-0.2, kernelversion=3.18.21-1-rackos, operatingsystem=Debian GNU/Linux 7 (wheezy) (containerized), storagedriver=aufs bf76bea4-47ef-43ac-a7ae-67a6e6db15bf-n2: 126.96.36.199:42376 └ Containers: 2 └ Reserved CPUs: 0 / 12 └ Reserved Memory: 0 B / 4.2 GiB └ Labels: executiondriver=native-0.2, kernelversion=3.18.21-1-rackos, operatingsystem=Debian GNU/Linux 7 (wheezy) (containerized), storagedriver=aufs bf76bea4-47ef-43ac-a7ae-67a6e6db15bf-n3: 188.8.131.52:42376 └ Containers: 2 └ Reserved CPUs: 0 / 12 └ Reserved Memory: 0 B / 4.2 GiB └ Labels: executiondriver=native-0.2, kernelversion=3.18.21-1-rackos, operatingsystem=Debian GNU/Linux 7 (wheezy) (containerized), storagedriver=aufs CPUs: 36 Total Memory: 12.6 GiB Name: a892be77e40c
for each node we need to get the servicenet ip:
$ docker run --net=host \ --env constraint:node==bf76bea4-47ef-43ac-a7ae-67a6e6db15bf-n1 \ racknet/ip service ipv4 10.176.230.11 --env constraint:node==bf76bea4-47ef-43ac-a7ae-67a6e6db15bf-n2 \ racknet/ip service ipv4 10.176.230.12 $ docker run --net=host \ --env constraint:node==bf76bea4-47ef-43ac-a7ae-67a6e6db15bf-n3 \ racknet/ip service ipv4 10.176.230.13
Start your first MySQL server:
$ docker run --detach \ --name database01 \ --env constraint:node==bf76bea4-47ef-43ac-a7ae-67a6e6db15bf-n1 \ -e DEBUG=1 -e MYSQL_USER=admin \ -e MYSQL_PASS=notthispassword -e REP_PASS=woopdedoo \ -e HOST=10.176.230.11 -e SERVICE_DISCOVERY=env \ -p 10.176.230.11:3306:3306 \ -p 10.176.230.11:4444:4444 \ -p 10.176.230.11:4567:4567 \ -p 10.176.230.11:4568:4568 \ paulczar/percona-galera
Second and third:
$ docker run -d \ --name database02 \ --env constraint:node==bf76bea4-47ef-43ac-a7ae-67a6e6db15bf-n2 \ -e MYSQL_USER=admin \ -e CLUSTER_MEMBERS=10.176.230.11 \ -e MYSQL_PASS=notthispassword -e REP_PASS=woopdedoo \ -e HOST=10.176.230.12 -e SERVICE_DISCOVERY=env \ -p 10.176.230.12:3306:3306 \ -p 10.176.230.12:4444:4444 \ -p 10.176.230.12:4567:4567 \ -p 10.176.230.12:4568:4568 \ paulczar/percona-galera $ docker run -d \ --name database03 \ --env constraint:node==bf76bea4-47ef-43ac-a7ae-67a6e6db15bf-n3 \ -e MYSQL_USER=admin \ -e CLUSTER_MEMBERS=10.176.230.11 \ -e MYSQL_PASS=notthispassword -e REP_PASS=woopdedoo \ -e HOST=10.176.230.13 -e SERVICE_DISCOVERY=env \ -p 10.176.230.13:3306:3306 \ -p 10.176.230.13:4444:4444 \ -p 10.176.230.13:4567:4567 \ -p 10.176.230.13:4568:4568 \ paulczar/percona-galera
wait a minute or so then check status:
docker exec -ti database01 mysql -e "SHOW STATUS LIKE 'wsrep_cluster%'" +--------------------------+--------------------------------------+ | Variable_name | Value | +--------------------------+--------------------------------------+ | wsrep_cluster_conf_id | 3 | | wsrep_cluster_size | 3 | | wsrep_cluster_state_uuid | 2882bcb7-ab3b-11e5-ab75-2b510ef0ec6f | | wsrep_cluster_status | Primary | +--------------------------+--------------------------------------+
Paul Czarkowski (firstname.lastname@example.org)
Copyright 2014 Paul Czarkowski Copyright 2015 Paul Czarkowski
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