Notes on Ansible
Ansible is a system for provisioning servers and automatic deployments.
I recently used it for deploying a website written in Go and it worked well for both provisioning and deployment.
Provisioning is about setting up pre-requisites that only have to be done once.
Deployment is about updating the project to the latest version. It happens as often as you update the project.
In case of a simple website, provisioning Ubuntu 14.10 server involved the following steps:
Deployment involves:

Ansible process

Things are simpler if you you create ansible.cfg. For this project, mine was:
hostfile = inventory
remote_user = root
The file inventory contains list of servers we’ll operate on:
sumatrawebsite-provision ansible_ssh_host=sumatrapdfreader.org ansible_ssh_user=root
sumatrawebsite ansible_ssh_host=sumatrapdfreader.org ansible_ssh_user=sumatrawebsite
Notice that we only operate against a single server but we have 2 different configuration:
Let’s create provisioning.sh helper script:
ansible-playbook provisioning.yml
This is how we run Ansible playbook. Playbook provisioning.yml is:
- name: initial server setup
  hosts: sumatrawebsite-initial
  sudo: True
    - name: create a user
      user: name=sumatrawebsite group=sumatrawebsite groups="sudo" shell=/bin/bash
    - name: make user a sudoer
      lineinfile: dest=/etc/sudoers state=present regexp='^%sumatrawebsite' line='%sumatrawebsite ALL=(ALL) NOPASSWD:ALL'
    - name: create user's .ssh directory
      file: path=/home/sumatrawebsite/.ssh state=directory owner=sumatrawebsite group=sumatrawebsite mode=0755
    - name: copy existing ssh key
      command: cp /root/.ssh/authorized_keys /home/sumatrawebsite/.ssh/authorized_keys
    - name: configure authorized_keys
      file: path=/home/sumatrawebsite/.ssh/authorized_keys mode=0644 owner=sumatrawebsite group=sumatrawebsite
    - name: create directory for nginx logs
      file: >
        path=/var/log/nginx/sumatrawebsite/ state=directory mode=0755
    - name: copy nginx config file
      copy: src=nginx.conf dest=/etc/nginx/sites-available/sumatrawebsite
    - name: enable website
      file: >
    - name: restart nginx
      service: name=nginx state=restarted
If you know Unix, you can figure out what those commands do. Ansible playbook consists mostly of commands run on the server.
The good thing about Ansible is that it avoids re-doing commands. For example, user: name=sumatrawebsite group=sumatrawebsite groups="sudo" shell=/bin/bash creates a new user with certain properties.
If a user already exists, Ansible is smart enough to not execute any commands.
Written on Nov 27 2014. Topics: programming.
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