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HA - Active Backup

Active backup server side solution for easyredmine. Based on: - Percona master - slave replication - rsync script for syncing files from master to slave

Auto-takeover is not included and should be provided by 3rd party proxy, or by HA-proxy for example

Pre-installation requirements

  • both servers must be deployed by easy_cloud_deploy.yml playbook
  • TCP ports 22 and 3306 must be open between master and slave nodes
  • application on master node must works

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EXAMPLE

# add this to host_vars/$MASTER_SERVER_NAME.yml
db_server_id: 1

firewall_v4_host_rules:
400 allow mysql replication traffic:
- -A INPUT -p tcp --dport 3306 -j ACCEPT -s 85.18.13.28/32 -m comment --comment "allow MySQL access from slave"
- -A INPUT -p tcp --dport 22 -j ACCEPT -s 85.18.13.28/32 -m comment --comment "allow SSH access from slave"


# add this to host_vars/$SLAVE_server_name.yml
mysql_replication_user: repliuser
mysql_replication_password: secretpassword
server_id: 2

application: velmidulezitymegaklient.easyproject.com
git: git@git.easy.cz:easyproject_com/stable.git
master: hot-master.cz.easy2.cloud

# is not required, but in future it could be master so we can prepare it
firewall_v4_host_rules:
400 allow mysql replication traffic:
- -A INPUT -p tcp --dport 3306 -j ACCEPT -s 85.18.13.21/32 -m comment --comment "allow MySQL access from master"
- -A INPUT -p tcp --dport 22 -j ACCEPT -s 85.18.13.21/32 -m comment --comment "allow SSH access from master"

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installation

Don’t start before pre-installation requirements are met!!!!

  1. Check master and slave nodes met requirements and host_vars yaml contain required variables
  2. Redeploy master database and firewall role just to be sure ansible and server state match
  3. Redeploy whole slave node
  4. Run playbook hot-standby.yml ansible-playbook -i easy_cloud hot-standby.yml –limit “slave_node*” –diff
  5. copy app_name/config/database.yml from master to slave
  6. reload app on slave