From fc65595bce678304c023cf61a443bd22f41b1509 Mon Sep 17 00:00:00 2001
From: Johanna Dorothea Reichmann <transcaffeine@finallycoffee.eu>
Date: Sun, 13 Mar 2022 08:41:06 +0100
Subject: [PATCH] feat(postgres_exporter): add ansible role for deployment
 using docker

---
 README.md                                 |  3 +++
 roles/postgres_exporter/README.md         | 18 +++++++++++++
 roles/postgres_exporter/defaults/main.yml | 31 +++++++++++++++++++++++
 roles/postgres_exporter/tasks/main.yml    | 30 ++++++++++++++++++++++
 4 files changed, 82 insertions(+)
 create mode 100644 roles/postgres_exporter/README.md
 create mode 100644 roles/postgres_exporter/defaults/main.yml
 create mode 100644 roles/postgres_exporter/tasks/main.yml

diff --git a/README.md b/README.md
index aa06751..e6262a5 100644
--- a/README.md
+++ b/README.md
@@ -11,6 +11,9 @@ metrics or alerting.
   manager receiver which posts alerts to a configured matrix channel
   using alertmanagers' webhooks.
 
+- [`postgres_exporter`](roles/postgres_exporter/README.md): Prometheus
+  exporter for postgres databases, in a docker container.
+
 ## License
 
 [CNPLv7+](LICENSE.md): Cooperative Nonviolent Public License
diff --git a/roles/postgres_exporter/README.md b/roles/postgres_exporter/README.md
new file mode 100644
index 0000000..388afe7
--- /dev/null
+++ b/roles/postgres_exporter/README.md
@@ -0,0 +1,18 @@
+# `finallycoffee.observability.postgres_exporter` ansible role
+
+## Overview
+
+Ansible role to deploy [`postgres_exporter`](https://github.com/prometheus-community/postgres_exporter),
+running in a docker container.
+
+## Configuration
+
+Set `postgres_exporter_db_[host|post|user|pass]` according to your
+databases configuration, and scrape the container on it's port `9187`
+(e.g.: `http://{container_ip}:9187/metrics`).
+
+For more configuration options using environment variables, see the
+[official README](https://github.com/prometheus-community/postgres_exporter)
+and set the configuration in `postgres_exporter_container_env` to override
+the defaults.
+
diff --git a/roles/postgres_exporter/defaults/main.yml b/roles/postgres_exporter/defaults/main.yml
new file mode 100644
index 0000000..a6d92f3
--- /dev/null
+++ b/roles/postgres_exporter/defaults/main.yml
@@ -0,0 +1,31 @@
+---
+
+postgres_exporter_version: "0.10.1"
+postgres_exporter_user: root
+postgres_exporter_create_user: false
+
+postgres_exporter_db_host: ~
+postgres_exporter_db_user: postgres
+postgres_exporter_db_pass: ~
+postgres_exporter_db_port: ~
+postgres_exporter_db_sslmode: false
+
+postgres_exporter_container_name: postgres_exporter
+postgres_exporter_container_image_name: quay.io/prometheuscommunity/postgres-exporter
+postgres_exporter_container_image_tag: ~
+postgres_exporter_container_image_ref: "{{ postgres_exporter_container_image_name }}:{{ postgres_exporter_container_image_tag | default('v' + postgres_exporter_version, True) }}"
+postgres_exporter_container_networks: ~
+postgres_exporter_container_purge_networks: false
+postgres_exporter_container_volumes: []
+postgres_exporter_container_ports: ~
+postgres_exporter_container_env:
+  DATA_SOURCE_NAME: >-
+    user={{ postgres_exporter_db_user }}
+    host={{ postgres_exporter_db_host }}
+    sslmode={{ 'enable' if postgres_exporter_db_sslmode else 'disable' }}
+    {%- if postgres_exporter_db_pass -%} pass={{ postgres_exporter_db_pass }}{% endif -%}
+    {%- if postgres_exporter_db_port -%} port={{ postgres_exporter_db_port }}{% endif -%}
+postgres_exporter_container_labels:
+  VERSION: "{{ postgres_exporter_version }}"
+postgres_exporter_container_user: "{{ postgres_exporter_user if not postgres_exporter_create_user else postgres_exporter_user_info.uid }}"
+postgres_exporter_container_restart_policy: unless-stopped
diff --git a/roles/postgres_exporter/tasks/main.yml b/roles/postgres_exporter/tasks/main.yml
new file mode 100644
index 0000000..7f1c2fe
--- /dev/null
+++ b/roles/postgres_exporter/tasks/main.yml
@@ -0,0 +1,30 @@
+---
+
+- name: Ensure user '{{ postgres_exporter_user }}' exists
+  user:
+    name: "{{ postgres_exporter_user }}"
+    state: present
+    system: yes
+  register: postgres_exporter_user_info
+  when: postgres_exporter_create_user
+
+- name: Ensure container image '{{ postgres_exporter_container_image_ref }}' is available
+  community.docker.docker_image:
+    name: "{{ postgres_exporter_container_image_ref }}"
+    state: present
+    source: pull
+    force_source: "{{ 'yes' if postgres_exporter_container_image_tag else 'no' }}"
+
+- name: Ensure postgres exporter container '{{ postgres_exporter_container_name }}' is running
+  docker_container:
+    name: "{{ postgres_exporter_container_name }}"
+    image: "{{ postgres_exporter_container_image_ref }}"
+    networks: "{{ postgres_exporter_container_networks | default(omit) }}"
+    purge_networks: "{{ postgres_exporter_container_purge_networks }}"
+    volumes: "{{ postgres_exporter_container_volumes | default(omit) }}"
+    labels: "{{ postgres_exporter_container_labels | default(omit) }}"
+    ports: "{{ postgres_exporter_container_ports | default(omit) }}"
+    user: "{{ postgres_exporter_container_user }}"
+    env: "{{ postgres_exporter_container_env }}"
+    restart_policy: "{{ postgres_exporter_container_restart_policy }}"
+    state: started