Use Case 03: Application Maintenance with AS3

OVERVIEW

Application-Maintenance.yaml is a templated Ansible Playbook that demonstrates the ability to change the state (enable/disable/offline) of traffic flowing to web-server(s) in a load balancing pool.

There are times where web servers are taken offline to provide upgrades, troubleshooting, or even replacement.

This playbook allows the ability to enable, disable or offline a specific or array of pool members (e.g. [hostname]:[port] or [ip address]:[port]); This script can also affect "All" of the members of a selected pool.

HIGHLIGHTS

1. This declarative code is designed to run and change the state of nodes within a F5 pool, because this is declarative and a declaration defines the end-state of an environment.
2. Due to being declarative, if a node is disabled on the first run but then changed not be disabled on the second run of the code the node will become active automatically.

EXAMINING THE CODE

1. In the VSCode (Code-Server) on the left menus expand f5-bd-ansible-labs --> 401-F5-AppWorld-Lab --> AS3 --> 03-Application-Maintenance-AS3 --> and lets first examine the vars/f5_vars.yml file, this vars file is similar to our modules section vars.

   • The F5_Pool_Members variable can be set in the array to a specific node and port (e.g. [hostname]:[port] or [ip address]:[port]) or can be set to (All) the code is designed to be able to determine if you want a specific node or all nodes to have a changed state.
   • The F5_Pool_Node_State variable can be set to 3 states (Enabled, Disabled, Offline) just like you could do to pool members on a BIG-IP Pool within the GUI.

2. Now lets examine a the specific section within the declaration j2/app_maint.j2 this code loops and iterates over the pool_members variable which is our inventory file group called web it will use the information from the inventory with the F5_Pool_Members and F5_Pool_Node_State variables to determine the state of the nodes.

   "members": [
      {%  for item in pool_members %}
      {
         "servicePort": 80,
         "serverAddresses": [
            "{{hostvars[item]['private_ip'] }}"
         ],
         {%  if hostvars[item]['inventory_hostname'] in F5_Pool_Members %}
            "adminState": "{{F5_Pool_Node_State|lower}}"
         {%  elif "all" in F5_Pool_Members|lower %}
            "adminState": "{{F5_Pool_Node_State|lower}}"
         {%  else  %}
            "adminState": "enable"
         {% endif %}
      }{{ ", " if not loop.last else ""}}
      {% endfor %}
   ]
   

RUNNING THE TEMPLATE

Running this template assumes that a F5 BIG-IP instance, necessary webservers and Ansible node are available.

1. Ensure you are using a terminal from VSCode (UDF --> Ansible-Node --> Access --> Code-Server --> Password: Ansible123! --> Trust --> Terminal --> New Terminal)

2. Change Directory in the Ansible Host to the use-cases repo previously downloaded

   cd ~/f5-bd-ansible-labs/401-F5-AppWorld-Lab/AS3/03-Application-Maintenance-AS3
   

3. Run the Ansible Playbook Application-Maintenance.yaml

   ansible-navigator run Application-Maintenance.yaml --mode stdout
   

   Note

   By default a VIP and pool will be created during the execution of the code, then the code will disable a single node in that created pool.

   Modification of the vars/f5_vars.yml file can change the pool, node(s) and state which can be modified within the f5_vars.yml.

TESTING AND VALIDATION

This section assumes knowledge of how to operate BIG-IP commands and networking.

VERIFYING NODE MAINTENANCE:

Access Using F5 UDF Console:

Using the External Client (UDF --> Components --> External Client --> Access --> Firefox)

• In the Bookmarks bar you can select the Ansible Labs Folder and goto 401 - Labs and Select Use Case 3
• OR within the browser you can browse to https://10.1.20.30:8083/
• Browse the page and notice that only NODE2 is the only responsive Node as Node 1 was disabled.

BIG-IP CONFIGURATION VERIFICATION:

Using F5 UDF:

• BIG-IP - (In UDF --> Components --> BIG-IP --> Access --> TMUI) - This will popup a webpage to access the F5 Login Page

  • Login to the BIG-IP
  • Navigate to Local Traffic --> Pools
  • Change the Partition (Top Right Corner) to "WorkshopExample"
  • Click on the pool you selected while running the playbook
  • View the members of the pool and verify their state based on action choosen while running the playbook

• Login information for the BIG-IP:

  • username: admin
  • password: Ansible123!