Basic Error Handling | Error Handling

Introduction

Error handling is a crucial part of any automation workflow. In Ansible, you can control how tasks and playbooks respond to errors using various mechanisms. This tutorial will cover the basics of error handling in Ansible, including common strategies and examples.

Ignoring Errors

Sometimes, you may want a task to continue executing even if it fails. You can achieve this by using the ignore_errors directive.

- name: Run a command that might fail
  command: /bin/false
  ignore_errors: yes

In this example, even if the command fails, Ansible will continue to execute the subsequent tasks.

Handling Failures with `failed_when`

The failed_when directive allows you to specify a condition that determines whether a task has failed.

- name: Check service status
  shell: systemctl status myservice
  register: result
  failed_when: "'inactive' in result.stdout"

Here, the task will be marked as failed only if the string "inactive" is found in the command's output.

Using `rescue` and `always` Blocks

The block module allows you to group tasks together and handle errors using rescue and always blocks.

- name: Error handling with block
  block:
    - name: Task that might fail
      command: /bin/false
  rescue:
    - name: Task to run on failure
      debug:
        msg: "The command failed"
  always:
    - name: Task to always run
      debug:
        msg: "This runs regardless of success or failure"

In this example, if the command fails, the task in the rescue block will execute. The task in the always block will run regardless of the outcome.

Registering and Analyzing Results

You can use the register directive to capture the result of a task and analyze it for error handling.

- name: Run a command and register the result
  command: /bin/false
  register: result

- name: Display the result
  debug:
    var: result

- name: Fail if command failed
  fail:
    msg: "The command failed"
  when: result.failed

Here, the result of the command is registered in a variable, and a subsequent task checks if the command failed, triggering a failure message if it did.

Conclusion

Basic error handling in Ansible involves using directives like ignore_errors, failed_when, rescue, and always. These tools allow you to build robust automation workflows that can handle errors gracefully and continue executing as needed.

Basic Error Handling in Ansible