Ansible_MHA

#####The playbook install MySQL instances, set up replication and configure MHA Currently it supports the following:

• Linux user management
• Automated master-slave replication setup. You can add new slaves to a cluster online(xtrabackup stream)
• Semi-automated failover support with MHA
• my.cnf file creation based on available ram with templates
  • custom my.cnf setup
  • MySQL user management

###How to install

Requirements:

• ssh client
• ansible
• EC2 access

AWS Console:

• generate AWS key
• create a security group with similar or wider policy:
  • ssh from your ip
  • ssh,mysql traffic between the machines
• generate an ssh key and add it to EC2

add your credentials (aws key, private key, pubic key) to the encrypted system.yml (default password: 42)

ansible-vault edit group_vars/system.yml

you can change the password with

ansible-vault rekey group_vars/system.yml

###Spin up instances Spin up 4 instances via the AWS consolte, we will use them as:

• 1 master
• 2 slaves
• 1 MHA manager node

AMI: RightImage_CentOS_6.5_x64_v14.1.3_HVM_EBS (ami-14211709 - us-east)

Define at least these tags:

• Name = anything
• Env = anything: dev

Security group: see above

Edit the sample_cluster inventory file and change the ip addresses

16:07:55-mszel@42:~/github/ansible_mha$ cat clusters/sample_cluster
#ROLES
======
[system]
52.28.26.105   mycnf=plsc_s1 mysql_role=master  nickname=dev-plsc-m
52.28.23.4    mycnf=plsc_s2 mysql_role=slave  nickname=dev-plsc-s1
52.28.19.44   mysql_role=slave  nickname=dev-plsc-s2

52.28.3.145   mysql_role=mha_manager ephemeral=true

[system:vars]
cluster_id=dev-plscdemo
env=dev

[databases:vars]
master_host=52.28.26.105

# Group to install and configure MySQL
[databases]
52.28.26.105  mysql_role=master server_id=1
52.28.23.4   mysql_role=slave server_id=2 backup_src=52.28.26.105
52.28.19.44  mysql_role=slave server_id=3 backup_src=52.28.26.105

run the playbook

ansible-playbook -i clusters/sample_cluster setup.yml -e bootstrap_enabled=true --ask-vault-pass

#####All servers has read_only=1 set by default!!!

###MHA examples run these command on the ansible host: #####Connectivity test

ansible  -i clusters/sample_cluster system --limit  [ip_of_mha_manager_node]   -a "masterha_check_ssh --conf=/etc/mha_dev-plscdemo.cnf"

#####Replication test

ansible  -i clusters/sample_cluster system --limit  [ip_of_mha_manager_node]   -a "masterha_check_repl  --conf=/etc/mha_dev-plscdemo.cnf"

#####Online failover You can see the current topology in the output of the replication test.

ansible  -i clusters/sample_cluster system --limit  [ip_of_mha_manager_node]   -a "masterha_master_switch --master_state=alive --orig_master_is_new_slave --conf=/etc/mha_dev-plscdemo.cnf  --interactive=0 --new_master_host=[ip address of the chosen slave ]"

#####Failover with a dead master

ansible  -i clusters/sample_cluster system --limit  [ip_of_mha_manager_node]   -a "masterha_master_switch --master_state=dead --conf=/etc/mha_dev-plscdemo.cnf  --dead_master_host=[ip of the dead master] --interactive=0 --remove_dead_master_conf"

###TAGS #####'users' - User management If you want to add a new Linux user to the servers simply copy its public key to roles/common/files/users/ - filename will be the username. Once the file is deployed the users can connect to the servers with their own username and can sudo. If you want to delete a user, simply remove the file and run the playbook again. Run the following to apply the changes:

ansible-playbook -i clusters/sample_cluster setup.yml --tags users