Run command on the Ansible host

Question

Is it possible to run commands on the Ansible host?

My scenario is that I want to take a checkout from a git server that is hosted internally (and isn\'t accessible

Answer 1

From the Ansible documentation:

Delegation This isn’t actually rolling update specific but comes up frequently in those cases.

If you want to perform a task on one host with reference to other hosts, use the ‘delegate_to’ keyword on a task. This is ideal for placing nodes in a load balanced pool, or removing them. It is also very useful for controlling outage windows. Be aware that it does not make sense to delegate all tasks, debug, add_host, include, etc always get executed on the controller. Using this with the ‘serial’ keyword to control the number of hosts executing at one time is also a good idea:

---

- hosts: webservers
  serial: 5

  tasks:

  - name: take out of load balancer pool
    command: /usr/bin/take_out_of_pool {{ inventory_hostname }}
    delegate_to: 127.0.0.1

  - name: actual steps would go here
    yum:
      name: acme-web-stack
      state: latest

  - name: add back to load balancer pool
    command: /usr/bin/add_back_to_pool {{ inventory_hostname }}
    delegate_to: 127.0.0.1

These commands will run on 127.0.0.1, which is the machine running Ansible. There is also a shorthand syntax that you can use on a per-task basis: ‘local_action’. Here is the same playbook as above, but using the shorthand syntax for delegating to 127.0.0.1:

---

# ...

  tasks:

  - name: take out of load balancer pool
    local_action: command /usr/bin/take_out_of_pool {{ inventory_hostname }}

# ...

  - name: add back to load balancer pool
    local_action: command /usr/bin/add_back_to_pool {{ inventory_hostname }}

A common pattern is to use a local action to call ‘rsync’ to recursively copy files to the managed servers. Here is an example:

---
# ...
  tasks:

  - name: recursively copy files from management server to target
    local_action: command rsync -a /path/to/files {{ inventory_hostname }}:/path/to/target/

Note that you must have passphrase-less SSH keys or an ssh-agent configured for this to work, otherwise rsync will need to ask for a passphrase.