Exercise 2.0: Disabling a pool member

Objective

This time we are going to disable a pool member from the pool. The build syntax will demonstrate the removal of a node from the pool.

Build a Playbook that:

• Retrieve Facts from BIG-IP for the pools present on the BIG-IP (in our example only one pool is present)
• Display pools available
• Store the pool name as a fact
• Display all the pool members that belong to the pool
• Prompt the user to disable a particular member or disable all members of the pool
• Force the appropriate pool members offline

Guide

Step 1:

Use VS Code Explorer to create a new file called disable-pool-member.yml.

The Ansible node is equiped with Visual Studio Code and can be accessed via UDF ACCESS Methods.

Step 2:

Enter the following play definition into disable-pool-member.yml:

---
- name: "Disabling a pool member"
  hosts: lb
  gather_facts: false
  connection: local

Step 3

Add a tasks section and then set a fact for the provider. Once you set the provider you can re-use this key in future tasks instead of giving the server/user/password/server_port and validate_certs info to each task.

tasks:

- name: Setup provider
  set_fact:
   provider:
    server: "{{private_ip}}"
    user: "{{ansible_user}}"
    password: "{{ansible_ssh_pass}}"
    server_port: "8443"
    validate_certs: "no"

Step 4

Next, add a task to Retrieve Facts from BIG-IP for the subset ltm-pools

- name: Query BIG-IP facts
 bigip_device_info:
   provider: "{{provider}}"
   gather_subset:
     - ltm-pools
 register: bigip_facts

You DO NOT need to pass the server_ip/user/password etc. for each module going forward.

Step 5

Deploy ansible-playbook disable-pool-members.yml -vvvv and watch the outcome.

The -vvvv creates extra verbose and makes that you sew more output when the ansible playbook gets deployed

Step 6

Next, add a task to Display the pool information to the terminal window

- name: Display Pools available
  debug: "msg={{item.name}}"
  loop: "{{bigip_facts.ltm_pools}}"
  loop_control:
    label: "{{item.name}}"

Repeat Step 5 by deploying the Ansible playbook.

Step 7

Next, add a task to Store the pool name as a fact

- name: Store pool name in a variable
  set_fact:
    pool_name: "{{item.name}}"
  loop: "{{bigip_facts.ltm_pools}}"
  no_log: true

Repeat Step 5 by deploying the Ansible playbook.

Step 8

Next, add a task to Display members belonging to the pool

- name: "Show members belonging to pool {{pool_name}}"
  debug: "msg={{item}}"
  loop: "{{bigip_facts.ltm_pools | json_query(query_string)}}"
  vars:
    query_string: "[?name=='{{pool_name}}'].members[*].name[]"

Step 9

Next, add a task which will ask the user to enter one of two options:

• a Host:Port to disable a particular member
• ‘all’ to disable all members

- pause:
    prompt: "To disable a particular member enter member with format member_name:port \nTo disable all members of the pool enter 'all'"
  register: member_name

Step 10

Next, add a task which will Read the prompt information and disable all members or a single member based on the input from the user

- name: Disable ALL pool members
  bigip_pool_member:
    provider: "{{provider}}"
    state: "forced_offline"
    name: "{{item.split(':')[0]}}"
    pool: "{{pool_name}}"
    port: "{{item.split(':')[1]}}"
    host: "{{hostvars[item.split(':')[0]].ansible_host}}"
  loop: "{{bigip_facts.ltm_pools | json_query(query_string)}}"
  vars:
    query_string: "[?name=='{{pool_name}}'].members[*].name[]"
  when: '"all" in member_name.user_input'

- name: Disable pool member {{member_name.user_input}}
  bigip_pool_member:
    provider: "{{provider}}"
    state: "forced_offline"
    name: "{{member_name.user_input.split(':')[0]}}"
    pool: "{{pool_name}}"
    port: "{{member_name.user_input.split(':')[1]}}"
    host: "{{hostvars[member_name.user_input.split(':')[0]].ansible_host}}"
  when: '"all" not in member_name.user_input'

Step 10

Run the playbook - exit back into the command line of the control host and execute the following:

[centos@ansible ~]$ ansible-playbook disable-pool-member.yml

Playbook Output

The output will look as follows.

[centos@ansible ~]$ ansible-playbook disable-pool-member.yml

PLAY [Disabling a pool member] ******************************************************************************************************************************

TASK [Setup provider] *******************************************************************************************************************************
ok: [f5]

TASK [Query BIG-IP facts] ***********************************************************************************************************************************
changed: [f5]

TASK [Display Pools available] ******************************************************************************************************************************
ok: [f5] => (item=http_pool) => {
    "msg": "http_pool"
}

TASK [Store pool name in a variable] ************************************************************************************************************************
ok: [f5] => (item=None)
ok: [f5]

TASK [Show members belonging to pool http_pool] *************************************************************************************************************
ok: [f5] => (item=host1:80) => {
    "msg": "host1:80"
}
ok: [f5] => (item=host2:80) => {
    "msg": "host2:80"
}

TASK [pause] ************************************************************************************************************
[pause]
To disable a particular member enter member with format member_name:port
To disable all members of the pool enter 'all':
host1:80

TASK [Disable ALL pool members] ************************************************************************************************************************
skipping: [f5] => (item=host1:80)
skipping: [f5] => (item=host2:80)

TASK [Disable pool member host1:80] *************************************************************************************************************************
changed: [f5]

PLAY RECAP **************************************************************************************************************
f5                         : ok=7    changed=2    unreachable=0    failed=0

Solution

The solution will be provided by the instructor if you are stuck. The GUI should show something similar to the following with a black diamond indicating the specified node was forced offline.

You have finished this exercise. Click here to return to the lab guide