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I am trying to get all the installed YUM packages on an RHEL machine. I can easily get it through using shell commands which is not idempotent and would like to use the YUM command instead.
The shell command works fine:
- name: yum list packages
shell: yum list installed > build_server_info.config
But when I try to use the YUM command, it just executes, but it does not give any results:
- name: yum_command
action: yum list=${pkg} list=available
206
Ansible's yum module is used to manage packages with the yum package manager, which is the default on Red Hat based Linux distributions such as Red Hat Enterprise Linux and CentOS. Most systems require root/superuser permissions to manage packages, which means that become: true is required.
How can I check if a software package is installed on a Linux system using Ansible?. You can use Ansible automation tool to query installation status of a package on Linux a system. From the results a condition can then be used, e.g skip a task if package is installed, or install if check status is failed.
The first task you're telling the system to only update the yum cache. On the second you are effectively upgrading all packages to the latest version by using state=latest but you should also use update_cache=yes on the same task to be sure you're refreshing the cache with its latest package information.
I can easily get it through using shell commands which is not idempotent
You can't really talk about idempotence, when you are querying the current state of a machine.
"Idempontent" means that the task will ensure the machine is in the desired state no matter how many times you run a certain task.
When you query current state, you don't describe the desired state. No matter what you do, what method you use, the term "idempotent" is just not applicable.
Regarding your example, which does not give you results - you have repeated twice the same argument list and the task should fail (it doesn't, which looks like an Ansible quirk).
To get a list of installed packages, you should use:
- name: yum_command
yum:
list=installed
register: yum_packages
- debug:
var: yum_packages
It saves a list of dictionaries describing each package to a variable yum_packages.
You can then use a JSON Query Filter to get a single package (tar):
- debug: var=item
with_items: "{{yum_packages|json_query(jsonquery)}}"
vars:
jsonquery: "results[?name=='tar']"
to get a result like this:
"item": {
"arch": "x86_64",
"epoch": "2",
"name": "tar",
"nevra": "2:tar-1.26-31.el7.x86_64",
"release": "31.el7",
"repo": "installed",
"version": "1.26",
"yumstate": "installed"
}
Or only its version:
- debug: var=item
with_items: "{{yum_packages|json_query(jsonquery)}}"
vars:
jsonquery: "results[?name=='tar'].version"
"item": "1.26"
Since Ansible 2.5, you can also use the package_facts module: it will gather the list of installed packages as Ansible facts.
Example from the CPU:
- name: get the rpm package facts
package_facts:
manager: rpm
- name: show them
debug: var=ansible_facts.packages
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