Ansible "apt cache update failed" during postgresql repo install

Question

I'm trying to install postgresql on my remote host using Ansible. I have 2 solutions, but both work only half as I expect them to work/turn out.

1. Solution one (using Ansible apt_repository module);

- name: Get Postgres latest repository release
  become: yes
  apt_repository:
    repo: deb https://apt.postgresql.org/pub/repos/apt/ $(lsb_release -cs)-pgdg main
    state: present
    filename: pgdg.list

This option first looks like it's successful on execution, but eventually gives an error (apt cache update failed):

---

2. Solution two (use shell module)

- name: Get Postgres latest repository release
  become: yes
  shell: sh -c 'echo "deb  http://apt.postgresql.org/pub/repos/apt/ $(lsb_release -cs)-pgdg main" > /etc/apt/sources.list.d/pgdg.list'

This accomplishes exactly the same (correct me if I'm wrong) and later gives some other exception (No package matching):

So I'm not getting any further with my playbook, any tips?

My play to install postgresql-13 (or 14):

- name: Install Postgres dependencies (if not installed)
  become: yes
  apt:
    name: 
    - postgresql-{{ postgres_version }}
    - postgresql-doc-{{ postgres_version }}
    - postgresql-contrib
    - zabbix-sql-scripts
  when:
    - "not 'postgresql-13' in ansible_facts.packages"
    - "not 'postgresql-doc-13' in ansible_facts.packages"
    - "not 'postgresql-contrib' in ansible_facts.packages"
    - "not 'zabbix-sql-scripts' in ansible_facts.packages"

Repository keys are provided in another play and performs without errors.

This is executed on a host with Ubuntu 20.04LTS, Ansible version 2.9.6, Python version 3.8.10

I have searched for both individual problems but did not find a specific answer that solved my problem.

If if perform the same as Ansible manually, it all installs fine (commands used):

sudo sh -c ‘echo “deb http://apt.postgresql.org/pub/repos/apt $(lsb_release -cs)-pgdg main” > /etc/apt/sources.list.d/pgdg.list’

wget --quiet -O - https://www.postgresql.org/media/keys/ACCC4CF8.asc | sudo apt-key add -

sudo apt-get update

sudo apt-get -y install postgresql-13 postgresql-doc-13

Edit: Seemed I also had a quote (") missing at the start of my repo link (before deb https://...).

I had: repo: deb https://apt.postgresql.org/pub/repos/apt/ $(lsb_release -cs)-pgdg main"

Should be: "repo: deb https://apt.postgresql.org/pub/repos/apt/ $(lsb_release -cs)-pgdg main"

Answer 1

Basically, it must be said that an Ansible module, such as apt_repository is generally preferable to the shell module.

However, you have a few mistakes in your approach.

As you can see, apt_repository automatically updates the package sources, i.e. the repository key must already exist. You can add the repository key with the apt_key module, but you need to have the gpg package installed, which you should ensure first.

From this follows:

1. install gpg

   - name: Ensure gpg is installed
     apt:
       name: gpg
   

2. add repository key

   - name: Add repository signing key
     apt_key:
       url: "https://www.postgresql.org/media/keys/ACCC4CF8.asc"
       state: present
   

3. add repository source

   - name: Add postgresql repository
     apt_repository:
       repo: "deb https://apt.postgresql.org/pub/repos/apt/ {{ ansible_distribution_release }}-pgdg main"
       state: present
       filename: pgdg
   

When using apt_repository one of your problems was that you left $(lsb_release -cs) unchanged, but this only works via the shell, instead you have to use the variable ansible_distribution_release when using Ansible. Also, the filename parameter does not need an extension (.list), as the documentation tells you: "The .list extension will be automatically added." Your specification creates the file pgdg.list.list.

Again, as a whole playbook:

- name: Database Server
  hosts: databaseserver
  become: yes

  tasks:
    - name: Ensure gpg is installed
      apt:
        name: gpg

    - name: Add repository signing key
      apt_key:
        url: "https://www.postgresql.org/media/keys/ACCC4CF8.asc"
        state: present

    - name: Add postgresql repository
      apt_repository:
        repo: "deb https://apt.postgresql.org/pub/repos/apt/ {{ ansible_distribution_release }}-pgdg main"
        state: present
        filename: pgdg

Now you should be able to install the desired packages, if they are provided by the included repository.