Managing Packages

Using Modules to Manage Packages

Managing software packages on managed nodes is one of the firstrequirements when working with Ansible. Different modules are available. Table 12-2 provides an overview.

Table 12-2 Software Management Modules Overview

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Configuring Repository Access

Before you can manage any software packages, you need to set up access to a repository. To do so, the yum_repository module is provided. If you have worked with yum repository files in the /etc/yum.repos.d/ directory, using the yum_repository module is not difficult because it uses the same information.

Listing 12-1 shows an example of a playbook that sets up access to a yum repository. Notice that this is an example only, and it doesn’t work yet because the repository has not been set up yet.

Listing 12-1 Configuring Repository Access

::: pre_1 — - name: setting up repository access hosts: all tasks: - name: connect to example repo yum_repository: name: example repo description: RHCE8 example repo file: examplerepo baseurl: ftp://control.example.com/repo/ gpgcheck: no :::

While setting up repository access, you should use a few arguments. You can see an example of them in Listing 12-1. Table 12-3 provides an overview.

::: group Table 12-3 yum_repository Key Arguments

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Notice that use of the gpgcheck argument is recommended but not mandatory. Most repositories are provided with a GPG key to verify that packages in the repository have not been tampered with. However, if no GPG key is set up for the repository, the gpgcheck parameter can be set to no to skip checking the GPG key.

Managing Software with yum

The yum module can be used to manage software packages. You use it to install and remove packages or to update packages. This can be done for individual packages, as well as package groups and modules. Let’s look at some examples that go beyond the mere installation or removal of packages, which was covered sufficiently in earlier chapters.

Listing 12-2 shows a module that will update all packages on this system.

Listing 12-2 Using yum to Perform a System Update

::: pre_1 — - name: updating all packages hosts: ansible2 tasks: - name: system update yum: name: ’*’ state: latest :::

Notice the use of the name argument to the yum module. It has ’*’ as its argument. To prevent the wildcard from being interpreted by the shell, you must make sure it is placed between single quotes.

Listing 12-3 shows an example where yum package groups are used to install the Virtualization Host package group.

Listing 12-3 Installing Package Groups

::: pre_1 — - name: install or update a package group hosts: ansible2 tasks: - name: install or update a package group yum: name: ’@Virtualization Host’ state: latest :::

When a yum package group instead of an individual package needs to be installed, the name of the package group needs to start with an at sign (@), and the entire package group name needs to be put between single quotes. Also notice the use of state: latest in Listing 12-3. This line ensures that the packages in the package group are installed if they have not been installed yet. If they have already been installed, they are updated to the latest version.

A new feature in RHEL 8 is the yum AppStream module. Modules as listed by the Linux yum modules list command can be managed with the Ansible yum module also. Working with yum modules is similar to working with yum package groups. In the example in Listing 12-4, the main difference is that a version number and the installation profile are included in the module name.

Listing 12-4 Installing AppStream Modules with the yum Module

::: pre_1 — - name: installing an AppStream module hosts: ansible2 tasks: - name: install or update an AppStream module yum: name: ’@php:7.3/devel’ state: present :::

::: note

Note

When using the yum module to install multiple packages, you can provide the name argument with a list of multiple packages. Alternatively, you can provide multiple packages in a loop. Of these solutions, using a list of multiple packages as the argument to name is always preferred. If multiple package names are provided in a loop, the module must execute a task for every single package. If multiple package names are provided as the argument to name, yum can install all these packages in one single task.

:::

Managing Package Facts

When Ansible is gathering facts, package facts are not included. To include package facts as well, you need to run a separate task; that is, you need to use the package_facts module. Facts that have been gathered about packages are stored to the ansible_facts.packages variable. The sample playbook in Listing 12-5 shows how to use the package_facts module.

Listing 12-5 Using the package_facts Module to Show Package Details

::: pre_1 — - name: using package facts hosts: ansible2 vars: my_package: nmap tasks: - name: install package yum: name: “{{ my_package }}” state: present - name: update package facts package_facts: manager: auto - name: show package facts for {{ my_package }} debug: var: ansible_facts.packages[my_package] when: my_package in ansible_facts.packages :::

As you can see, the package_facts module does not need much to do its work. The only argument used here is the manager argument, which specifies which package manager to communicate to. Its default value of auto automatically detects the appropriate package manager and uses that. If you want, you can specify the package manager manually, using any package manager such as yum or dnf. Listing 12-6 shows the output of running the Listing 12-5 playbook, where you can see details that are collected by the package_facts module.

Listing 12-6 Running ansible-playbook listing125.yaml Results

::: pre_1 [ansible@control rhce8-book]$ ansible-playbook listing125.yaml

PLAY [using package facts] **************************************************************

TASK [Gathering Facts] ******************************************************************
ok: [ansible2]

TASK [install package] ******************************************************************
ok: [ansible2]

TASK [update package facts] *************************************************************
ok: [ansible2]

TASK [show package facts for my_package] ************************************************
ok: [ansible2] => {
    "ansible_facts.packages[my_package]": [
        {
            "arch": "x86_64",
            "epoch": 2,
            "name": "nmap",
            "release": "5.el8",
            "source": "rpm",
            "version": "7.70"
        }
    ]
}

PLAY RECAP ******************************************************************************
ansible2                   : ok=4    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0

:::

In Exercise 12-1 you can practice working with the different tools Ansible provides for module management.

::: box Exercise 12-1 Managing Software Packages

1. Use your editor to create a new file with the name exercise121.yaml.

2. Write a play header that defines the variable my_package and sets its value to virt-manager:

---
- name: exercise121
  hosts: ansible2
  vars:
    my_package: virt-manager
  tasks:

3. Add a task that installs the package based on the name of the variable that was provided:

- name: install package
  yum:
    name: "{{ my_package }}"
    state: present

4. Add a task that gathers facts about installed packages:

- name: update package facts
  package_facts:
    manager: auto

5. As the last part of this exercise, add a task that shows facts about the package that you have just installed:

- name: show package facts for {{ my_package }}
  debug:
    var: ansible_facts.packages[my_package]
  when: my_package in ansible_facts.packages

6. Run the playbook using ansible-playbook exercise121.yaml and verify its output. :::