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68 lines
2.2 KiB
68 lines
2.2 KiB
LAMP Stack + HAProxy: Example Playbooks
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- Requires Ansible 1.2
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- Expects CentOS/RHEL 6 hosts
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This example is an extension of the simple LAMP deployment. Here we'll install
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and configure a web server with an HAProxy load balancer in front, and deploy
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an application to the web servers. This set of playbooks also have the
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capability to dynamically add and remove web server nodes from the deployment.
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It also includes examples to do a rolling update of a stack without affecting
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the service.
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You can also optionally configure a Nagios monitoring node.
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### Initial Site Setup
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First we configure the entire stack by listing our hosts in the 'hosts'
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inventory file, grouped by their purpose:
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[webservers]
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webserver1
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webserver2
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[dbservers]
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dbserver
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[lbservers]
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lbserver
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[monitoring]
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nagios
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After which we execute the following command to deploy the site:
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ansible-playbook -i hosts site.yml
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The deployment can be verified by accessing the IP address of your load
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balancer host in a web browser: http://<ip-of-lb>:8888. Reloading the page
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should have you hit different webservers.
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### Removing and Adding a Node
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Removal and addition of nodes to the cluster is as simple as editing the
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hosts inventory and re-running:
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ansible-playbook -i hosts site.yml
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### Rolling Update
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Rolling updates are the preferred way to update the web server software or
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deployed application, since the load balancer can be dynamically configured
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to take the hosts to be updated out of the pool. This will keep the service
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running on other servers so that the users are not interrupted.
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In this example the hosts are updated in serial fashion, which means that
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only one server will be updated at one time. If you have a lot of web server
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hosts, this behaviour can be changed by setting the 'serial' keyword in
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webservers.yml file.
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Once the code has been updated in the source repository for your application
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which can be defined in the group_vars/all file, execute the following
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command:
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ansible-playbook -i hosts rolling_update.yml
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You can optionally pass: -e webapp_version=xxx to the rolling_update
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playbook to specify a specific version of the example webapp to deploy.
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