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Ansible Error Handling


Ansible Error Handling

Error handling in Ansible is crucial for managing and maintaining infrastructure. Ansible provides several mechanisms for error handling. Here are some key concepts and strategies:


 


1.failed_when


You can use the failed_when and changed_when statements to control the conditions under which a task is considered failed or changed.


In Ansible, the failed_when parameter allows you to specify a condition under which a task should be considered failed even if it completes successfully. This can be useful in scenarios where a task's success doesn't necessarily mean the desired state is achieved.


[root@siddhesh ~]# cat error_handle.yml
---
- name: Verify Directory
  hosts: all
  tasks:
    - name: Create a directory
      file:
        path: /tmp/sid/testdirectory
        state: directory
      register: directory_result
      failed_when: "'already exists' in directory_result.msg"
[root@siddhesh ~]#

Explanation:

The file module is used to create a directory at the specified path.

The register keyword captures the result of the task in the variable directory_result.

The failed_when parameter checks if the substring "already exists" is present in the msg attribute of the directory_result. If it is, the task is considered failed.

Output :

[root@siddhesh ~]# ansible-playbook -i inventory error_handle.yml
PLAY [Verify Directory] *******************************************************************************************************************
TASK [Gathering Facts] ********************************************************************************************************************
ok: [jenkins.builddevops.com]
TASK [Create a directory] *****************************************************************************************************************
fatal: [jenkins.builddevops.com]: FAILED! => {"changed": false, "failed_when_result": "The conditional check ''already exists' in directory_result.msg' failed. The error was: error while evaluating conditional ('already exists' in directory_result.msg): 'dict object' has no attribute 'msg'. 'dict object' has no attribute 'msg'", "gid": 1000, "group": "centos", "mode": "0775", "owner": "centos", "path": "/tmp/sid/testdirectory", "size": 6, "state": "directory", "uid": 1000}
PLAY RECAP ********************************************************************************************************************************
jenkins.builddevops.com    : ok=1    changed=0    unreachable=0    failed=1    skipped=0    rescued=0    ignored=0
[root@siddhesh ~]#

2.ignore_errors


In Ansible, the ignore_errors parameter is used to specify whether to ignore errors that occur during the execution of a particular task. When ignore_errors is set to yes for a task, Ansible will continue executing subsequent tasks even if the current task fails.


[root@siddhesh ~]# cat create_file.yml
---
 - name: create test file
   hosts: jenkinshost
   tasks:
     - name: create file1
       command: touch /tmp/siddhesh/task1.txt
       ignore_errors: True
     - name: create file2
       command: touch /tmp/task3.txt
[root@siddhesh ~]#

In this playbook, Task 1: create file1

The first task is named "create file1."

It uses the command module to execute the touch command, creating an empty file at the path /tmp/siddhesh/task1.txt.

The ignore_errors: True parameter is set, meaning that if this task fails (e.g., if the file already exists), Ansible will continue executing subsequent tasks without raising an error.


Task 2: create file2

The second task is named "create file2."

It also uses the command module to execute the touch command, attempting to create an empty file at the path /tmp/task3.txt.


Output :

[root@siddhesh ~]# ansible-playbook -i inventory create_file.yml
PLAY [create test file] *******************************************************************************************************************
TASK [Gathering Facts] ********************************************************************************************************************
ok: [jenkins.builddevops.com]
TASK [create file1] ***********************************************************************************************************************
fatal: [jenkins.builddevops.com]: FAILED! => {"changed": true, "cmd": ["touch", "/tmp/siddhesh/task1.txt"], "delta": "0:00:00.005335", "end": "2023-12-21 17:18:46.888905", "msg": "non-zero return code", "rc": 1, "start": "2023-12-21 17:18:46.883570", "stderr": "touch: cannot touch ‘/tmp/siddhesh/task1.txt’: No such file or directory", "stderr_lines": ["touch: cannot touch ‘/tmp/siddhesh/task1.txt’: No such file or directory"], "stdout": "", "stdout_lines": []}
...ignoring
TASK [create file2] ***********************************************************************************************************************
changed: [jenkins.builddevops.com]
PLAY RECAP ********************************************************************************************************************************
jenkins.builddevops.com    : ok=3    changed=2    unreachable=0    failed=0    skipped=0    rescued=0    ignored=1
[root@siddhesh ~]#

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