Using Ansible: Wait and Recover SSH Service after Restart

Using Ansible to Wait and Recover SSH Service Restart

In this article, we will discuss how to use Ansible to wait and recover SSH service restart. Specifically, we will cover the following topics:

• Ansible playbooks and tasks
• Waiting for SSH service to restart
• Recovering from lost SSH connections
• Key concepts and examples

Ansible Playbooks and Tasks

Ansible is an open-source automation tool that allows you to define and execute tasks on remote servers using a simple and human-readable language. Ansible playbooks are written in YAML format and consist of a list of tasks that are executed in order.

In this article, we will focus on using Ansible to wait and recover SSH service restart. This is a common use case when changing SSH configuration or updating the SSH server software.

Waiting for SSH Service to Restart

When restarting the SSH service, it is important to wait for the service to fully restart before attempting to connect again. This can be done using the wait_for_connection module in Ansible. This module will wait for the connection to be established before moving on to the next task.

Here is an example of how to use the wait_for_connection module to wait for the SSH service to restart:

- name: Wait for SSH service to restart
  wait_for_connection:
    delay: 60
    timeout: 300

In this example, the wait_for_connection module will wait for 60 seconds before timing out after 300 seconds. This will give the SSH service enough time to fully restart before attempting to connect again.

Recovering from Lost SSH Connections

When changing SSH configuration or updating the SSH server software, it is possible that Ansible will lose its SSH connection to the remote server. In this case, it is important to have a way to recover from the lost connection and continue executing the playbook.

This can be done using the meta module in Ansible. The meta module allows you to specify a list of handlers that will be executed when a task fails. In this case, we can use the reconnect handler to recover from a lost SSH connection.

Here is an example of how to use the meta module to recover from a lost SSH connection:

- name: Change SSH configuration
  copy:
    src: /path/to/sshd\_config
    dest: /etc/ssh/sshd\_config
    validate: 'test -x /usr/sbin/sshd -T -f %s'
  notify: restart sshd
  meta:
    always\_run: true
    reset\_connection: true

- name: Wait for SSH service to restart
  wait_for_connection:
    delay: 60
    timeout: 300
  when: ansible\_ssh\_failed is defined
  meta:
    always\_run: true
    reset\_connection: true
  notify: restart sshd

In this example, the change SSH configuration task will copy a new SSH configuration file to the remote server and notify the restart sshd handler to restart the SSH service. If the SSH service is not restarted successfully, the wait\_for\_connection module will wait for 60 seconds before timing out after 300 seconds. If Ansible loses its SSH connection during this time, the meta module will reset the connection and continue executing the playbook.

Key Concepts and Examples

In this article, we have discussed how to use Ansible to wait and recover SSH service restart. Some key concepts and examples include:

• wait\_for\_connection: A module that waits for the connection to be established before moving on to the next task.
• meta: A module that allows you to specify a list of handlers that will be executed when a task fails.
• reconnect: A handler that recovers from a lost SSH connection and continues executing the playbook.

In this article, we have discussed how to use Ansible to wait and recover SSH service restart. By using the wait\_for\_connection and meta modules, you can ensure that the SSH service is fully restarted before attempting to connect again and recover from lost SSH connections. This is a key concept in using Ansible to automate tasks on remote servers.

References

• wait\_for\_connection module
• meta module
• Handlers: Running Operations on Failure