2 - Inventory & Ad-hoc commands

Objective

Explore and understand the lab environment. This exercise will cover

• Locating and understanding:

  • Ansible Automation Controller Inventory
  • Ansible Automation Controller Credentials

• Running ad hoc commands via the Ansible Automation Controller web UI

Guide

Examine an Inventory

The first thing we need is an inventory of your managed hosts. This is the equivalent of an inventory file in Ansible Engine. There is a lot more to it (like dynamic inventories) but let’s start with the basics.

• You should already have the web UI open, if not: Point your browser to the URL you were given, similar to https://demo.redhat.com/workshop/pm6xgd (the workshop ID will be different) and log in as admin. The password will be provided by the instructor.

There will be one inventory, the Workshop Inventory. Click the Workshop Inventory then click the Hosts button

The inventory information at ~/lab_inventory/hosts was pre-loaded into the Ansible Automation controller Inventory as part of the provisioning process.

[web]
node1 ansible_host=node1.example.com
node2 ansible_host=node2.example.com
node3 ansible_host=node3.example.com

[control]
ansible-1 ansible_host=ansible-1.example.com

Warning

In your inventory the IP addresses will be different, do not copy the values above!

Examine Machine Credentials

Now we will examine the credentials to access our managed hosts from Automation controller. As part of the provisioning process for this Ansible Workshop the Workshop Credential has already been setup.

In the Resources menu choose Credentials. Now click on the Workshop Credential.

Note the following information:

Parameter	Value	Description
Credential Type	Machine	Machine credentials define ssh and user-level privilege escalation access for playbooks. They are used when submitting jobs to run playbooks on a remote host.
Username	ec2-user	The user which matches our command-line Ansible inventory username for the other Linux nodes
SSH Private Key	Encrypted	Note that you can't actually examine the SSH private key once someone hands it over to Ansible Automation controller

Run Ad Hoc commands

It is possible to run run ad hoc commands from Ansible Automation controller as well.

Tip

Ensure that all hosts are available and can be included in automation jobs.
Got to Resources → Hosts and move the slider on the right to On for all hosts.

• In the web UI go to Resources → Inventories → Workshop Inventory

• Click the Hosts tab to change into the hosts view and select the three hosts node1 to node3 by ticking the boxes to the left of the host entries.

• Click Run Command button. In the next screen you have to specify the ad hoc command.

Within the Details window, select Module ping and click Next.

Within the Execution Environment window, select Default execution environment and click Next.

Within the Machine Credential window, select Workshop Credentials and click Launch.

Tip

The output of the results is displayed once the command has completed.

The simple ping module doesn’t need options. For other modules you need to supply the command to run as an argument. Try the command module to find the userid of the executing user using an ad hoc command.

• In the web UI go to Resources → Inventories → Workshop Inventory

• Click the Hosts tab to change into the hosts view and select the three hosts by ticking the boxes to the left of the host entries.

• Click Run Command button. In the next screen you have to specify the ad hoc command.

Within the Details window, select Module command, in Arguments type id and click Next.

Within the Execution Environment window, select Default execution environment and click Next.

Within the Machine Credential window, select Workshop Credentials and click Launch.

Tip

After choosing the module to run, Ansible Automation Controller will provide a link to the docs page for the module when clicking the question mark next to "Arguments". This is handy, give it a try.

How about trying to get some secret information from the system? Try to print out /etc/shadow.

• In the web UI go to Resources → Inventories → Workshop Inventory

• Click the Hosts tab to change into the hosts view and select the three hosts by ticking the boxes to the left of the host entries.

• Click Run Command button. In the next screen you have to specify the ad hoc command.

Within the Details window, select Module command, in Arguments type cat /etc/shadow and click Next.

Within the Execution Environment window, select Default execution environment and click Next.

Within the Machine Credential window, select Workshop Credentials and click Launch.

Warning

Expect an error!

Oops, the last one didn’t went well, all red.

Re-run the last ad hoc command but this time check the checkbox labeled Enable privilege escalation.

As you see, this time it worked. For tasks that have to run as root you need to escalate the privileges. This is the same as the become: yes used in your Ansible Playbooks.

Challenge Lab: Ad Hoc Commands

Okay, a small challenge: Run an ad hoc to make sure the package "tmux" is installed on all hosts. If unsure, consult the documentation either via the web UI as shown above or by running ansible-doc yum on your Automation controller control host.

Solution

• In the Web UI go to Resources → Inventories → Workshop Inventory.
• Click the Hosts tab to change into the hosts view and select the three hosts by ticking the boxes to the left of the host entries.
• Click Run Command button. In the next screen you have to specify the ad hoc command.
• Within the Details window, select Module yum, in Arguments type name=tmux, check Enable privilege escalation and click Next.
• Within the Execution Environment window, select Default execution environment and click Next.
• Within the Machine Credential window, select Workshop Credentials and click Launch.

Info

Notice how the package was installed via the "CHANGED" output. If you run the ad hoc command a second time, the output will mention "SUCCESS" and inform you via the message parameter that there is nothing to do.

Adjust AAP settings for additional ad-hoc module

The previous Challenge Lab made use of the yum module, this module only makes sense on older Fedora-based systems like RHEL 7 or RHEL 8 hosts.
Previously, we used the generic package module to install packages on the target systems. Let's add this module to the list of modules which can be used with ad-hoc commands.

• In the web UI go to Settings. In the Tab Jobs click on Jobs settings.

• At the bottom of the page, click the Edit button.

• In the textarea Ansible Modules Allowed for Ad Hoc Jobs, add "package", (in between mount and ping to keep the alphabatical order).

Warning

The textarea contains a JSON list! Ensure to use quotation marks and end the line with comma to keep the valid list structure.

• After adding the module to the list, scroll down to the bottom of the page and click the Save button.

Now, you are able to use the package module in the ad-hoc command, try to do the previous Challenge Lab by using this module.