demo

Demo - Redis

New Scenario - Default installation

1. Create empty role with defaults (yamllint, Docker, testinfra)

   molecule init role -r role-redis

2. molecule.yml - Swap containers for systemd containers

   platforms:
   - name: instance1
       image: jremitz/centos-systemd:latest
       privileged: true
       command: /usr/sbin/init
   

3. Create the platforms molecule create

4. Make our new redis role do something by adding a debug command in the tasks: tasks/main.yml

   ---
   - name: Demo output
     debug: msg="Redis role has run"

5. Test Driven Development (TDD) - Let's add some tests so it fails! Testinfra - host fixture molecule/default/tests/test_default.py

   def test_redis(host):
       assert host.package("redis").is_installed
       assert host.process.get(user="redis", comm="redis-server")
       assert host.run_expect([0], "redis-cli -p 6379 info")

6. requirements.yml - Add dependencies, where we're getting the code

   ---
   - src: geerlingguy.repo-epel
     name: epel
   - src: git+https://github.com/JRemitz/ansible-role-redis
     version: slave-master
     name: ansible-role-redis
     
   

7. Watch your tests fail (TDD) by converging and verifying the results

   molecule converge

   and now verify

   molecule verify

   You should have failed verify results with an AssertionError

   =================================== FAILURES ===================================
   ________________________ test_redis[ansible://instance] ________________________
   
   host = <testinfra.host.Host object at 0x7f659ee45350>
   
       def test_redis(host):
   >       assert host.package("redis").is_installed
   E       AssertionError: assert False
   E        +  where False = <package redis>.is_installed
   E        +    where <package redis> = <class 'testinfra.modules.base.RpmPackage'>('redis')
   E        +      where <class 'testinfra.modules.base.RpmPackage'> = <testinfra.host.Host object at 0x7f659ee45350>.package
   
   tests/test_default.py:18: AssertionError
   ===================== 1 failed, 1 passed in 13.47 seconds ======================

8. To fix this, let's now install epel, redis, and then re-verify by updating the playbook.yml and adding epel and ansible-role-redis roles

   ---
   - name: Converge
     hosts: all
     roles:
       - role: epel
       - role: ansible-role-redis
       - role: redis
   

9. Re-run converge

   molecule converge

   and verify

   molecule verify

   ============================= test session starts ==============================
   platform linux2 -- Python 2.7.5, pytest-3.6.3, py-1.5.4, pluggy-0.6.0
   rootdir: /vagrant_data/ansible-testing/demo/tmp/redis/molecule/default, inifile:
   plugins: testinfra-1.14.1
   collected 2 items
   
   tests/test_default.py ..                                                 [100%]
   
   ========================== 2 passed in 16.95 seconds ===========================

New Scenario - Test Replication

1. Create a replication scenario for the same role to test redis replication

   molecule init scenario -r role-redis -s replication

2. Move the default role's playbook up a level so it can be shared across scenarios and modify both scenario's molecule.yml and copy to the new replication scenario Molecule - coniguration

   provisioner:
     name: ansible
     playbooks:
       converge: ../playbook.yml

   NOTE - You will need to update the scenario name in the slave's molecule.yml if you copy from the default scenario

3. Update the molecule.yml for a master/slave relationship between the docker containers

   1. Expose ports: 6379 (master), 6380 (slave)

   2. Add second instance for slave

   3. Add master/slave child groups

      platforms:
      - name: instance1-master
          image: jremitz/centos-systemd:latest
          privileged: true
          command: /usr/sbin/init
          groups:
          - redis
          children:
          - redis_master
          exposed_ports:
          - 6379/tcp
          published_ports:
          - 0.0.0.0:6379:6379/tcp
      - name: instance2-slave
          image: jremitz/centos-systemd:latest
          privileged: true
          command: /usr/sbin/init
          groups:
          - redis
          children:
          - redis_slave
          exposed_ports:
          - 6380/tcp
          published_ports:
          - 0.0.0.0:6380:6380/tcp

   4. Add Ansible group vars for IP, port, and password

      provisioner:
      name: ansible
      playbooks:
          converge: ../playbook.yml
      inventory:
          group_vars:
          redis:
              redis_bind_interface: 0.0.0.0
              redis_requirepass: secret
          redis_slave:
              redis_port: 6380
              redis_slaveof: "{{ groups['redis_master'] | map('extract', hostvars, ['ansible_eth0','ipv4','address']) | first }} 6379"

4. After running converge

   molecule converge

   test the "external" connection outside of docker

   redis-cli -a secret info replication

5. Test linter in molecule.yml, flake8 - override options to allow longer lines if you run into issues linting your test cases

   verifier:
     name: testinfra
     lint:
       name: flake8
       options:
         max-line-length: 100

6. Update the test so that slave is connected and services are running

   def test_redis(host):
       assert host.package("redis").is_installed
       assert host.process.get(user="redis", comm="redis-server")
       vars = host.ansible.get_variables()
       if "redis_port" in vars:
           assert host.run_expect(
               [0], "redis-cli -p %s info" % vars["redis_port"])
   
   
   def test_redis_replication(host):
       vars = host.ansible.get_variables()
       if "redis_master" in vars["group_names"]:
           # Validate master replication
           result = host.run("redis-cli -a %s info replication" % vars["redis_requirepass"])
           assert "connected_slaves:1" in result.stdout
       else:
           # Validate slave replication
           result = host.run("redis-cli -a %s -p 6380 info replication" % vars["redis_requirepass"])
           assert "master_link_status:up" in result.stdout

7. After verifying that everything tests successfully

   molecule verify

   Ensure that everything works together by running end-to-end and validating all test cases/scenarios

   molecule test --all