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https://github.com/adfinis/mariadb-ansible-galera-cluster

Automated installation of MariaDB Galera Cluster using Ansible
https://github.com/adfinis/mariadb-ansible-galera-cluster

ansible automation cluster configuration-management galera mariadb-galera-cluster playbook

Last synced: 3 months ago
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Automated installation of MariaDB Galera Cluster using Ansible

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README 

        
:warning: This project is no longer being maintained :warning:

==============================================================



The code in this repository was implemented as a PoC for the MariaDB roadshow

and is not being maintained anymore.



Feel free to use the bootstrap logic implemtented in the Ansible tasks in your

own project, but we're not going to implement any changes going forward.



If you find the code in this repository helpful, but want to use it under a

different license please get in contact with us.



configuration management for MariaDB Galera cluster

===================================================



These roles allow you to automatically setup a MariaDB Galera cluster with sane

default settings.



These roles are currently only tested for RHEL/CentOS 7, but most tasks can be

reused for Debian or SUSE based distributions.



Prerequisites

-------------



The machine from which the playbook is being run needs to have Ansible >= 2.5

installed. For detailed information how to obtain current packages for your

distribution of choice have a look at the

[Ansible documentation](https://docs.ansible.com/ansible/intro_installation.html).



As we're accessing information from a group of hosts within these playbooks we

need to have fact caching enabled in Ansible. To, for example, cache using json

files in you homedirectory you would add the following lines to

``/etc/ansible/ansible.cfg``:



```

[defaults]

gathering = smart

fact_caching = jsonfile

fact_caching_connection = ~/.ansible/cache

```



For more information about other cache mechanisms have a look at the

[Ansible documentation](https://docs.ansible.com/ansible/playbooks_variables.html#fact-caching)

regarding fact-caching.



Installing requirements

-----------------------



To install the required packages and configure SELinux and the firewall you can

run only the tasks tagged with ``setup``



    ansible-playbook -i galera.hosts galera.yml --tags setup



Configure MariaDB Galera cluster

--------------------------------



To run all further tasks to configure MariaDB Galera cluster and add the

required user for the **S**tate **S**napshot **T**ransfer (SST) either skip the

tasks tagged ``setup`` or run the tags ``config`` or ``auth`` directly.



    ansible-playbook -i galera.hosts galera.yml --skip-tags setup



Bootstrapping MariaDB Galera cluster

------------------------------------



Bootstrapping the cluster can be done using a playbook dedicated for

bootstrapping the MariaDB Galera cluster called galera_bootstrap.yml



    ansible-playbook -i galera.hosts galera_bootstrap.yml



It uses the first node in the group ``galera_cluster`` to bootstrap the cluster.



Rolling MariaDB Galera cluster updates

--------------------------------------



The role ``galera_conf`` is set up to allow rolling updates of the configuration

of the Galera cluster. When the variable ``bootstrapped`` is set to ``yes`` the

``mariadb`` service is restarted after a change of the configuration. It is

important to note that the playbook contains the keyword ``serial: 1``, meaning

that the configuration is applied one node at a time so that the will never lose

quorum in the process of applying the new configuration.



    ansible-playbook -i galera.hosts galera_rolling_update.yml



Vagrant support

---------------



For the live demo during the presentation I've been using Vagrant and with the

following instructions you can use the Vagrantfile to perform those steps.



### Prerequisites



As we need support for Vagrant private_network we need Guest Additions

installed in the guest OS. The ``vagrant-vbguest`` plugins automatically

takes care of this.



    vagrant plugin install vagrant-vbguest



### Vagrant setup



By running `vagrant up` all Ansible tasks in the galera.yml playbook will be

run. To bootstrap the cluster afterwards a separate run of the

galera_bootstrap.yml playbook is required.



    PYTHONUNBUFFERED=1 ANSIBLE_FORCE_COLOR=true ANSIBLE_HOST_KEY_CHECKING=false ANSIBLE_SSH_ARGS='-o UserKnownHostsFile=/dev/null -o IdentitiesOnly=yes -o ControlMaster=auto -o ControlPersist=60s' ansible-playbook --connection=ssh --inventory-file=.vagrant/provisioners/ansible/inventory --sudo galera_bootstrap.yml