metrics: add postgres-exporter and pg-agent

* postgres-exporter for basic database metrics
  - pg-agent: optional, to identify query performence issues

Signed-off-by: Alexis Pentori <alexis@status.im>

README.md

@@ -67,6 +67,11 @@ Container share memory can be configured with:
 postgres_share_memory: '1g'
 ```
 
+Metrics exporter for query performance can be activated with:
+```yaml
+postgres_ha_perf_metrics_exporter_disabled: false
+```
+
 # Management
 
 The service is managed using [Docker Compose](https://docs.docker.com/compose/):
@@ -75,4 +80,5 @@ admin@node-01.example.org:/docker/postgres-ha % docker-compose ps
    Name                 Command                 State                    Ports
 --------------------------------------------------------------------------------------------
 postgres-ha   docker-entrypoint.sh -p 5433   Up (healthy)   5432/tcp, 0.0.0.0:5433->5433/tcp
+pg-metrics-exporter   /bin/postgres_exporter         Up             0.0.0.0:9187->9187/tcp
 ```

defaults/main.yml

@@ -51,6 +51,18 @@ postgres_ha_users: []
 #  - user: 'dbuser'
 #    pass: 'dbpass'
 
+# Metrics Exporter
+postgres_ha_metrics_exporter_cont_name: 'pg-metrics-exporter'
+postgres_ha_metrics_exporter_cont_version: 'v0.15.0'
+postgres_ha_metrics_exporter_cont_image: 'quay.io/prometheuscommunity/postgres-exporter:{{ postgres_ha_metrics_exporter_cont_version}}'
+postgres_ha_metrics_exporter_cont_port: 9187
+
+# Performence Metrics Exporter
+postgres_ha_perf_metrics_exporter_disabled: true
+postgres_ha_perf_metrics_exporter_cont_name: 'pg-perf-metrics-exporter'
+postgres_ha_perf_metrics_exporter_cont_version: '1.2.6'
+postgres_ha_perf_metrics_exporter_cont_image: 'ghcr.io/coroot/coroot-pg-agent:{{ postgres_ha_perf_metrics_exporter_cont_version }}'
+postgres_ha_perf_metrics_exporter_cont_port: 9188
 # Backups
 postgres_ha_backup: true
 postgres_ha_backup_enabled: true

tasks/consul.yml

@@ -24,3 +24,25 @@
             name:     'PostgreSQL {{ postgres_ha_replica_enabled | ternary("Replica", "Tables") }} Healthcheck'
             type:     'script'
             script:   '{{ postgres_ha_service_path }}/health.sh'
+      - name: 'postgres-metrics'
+        id:   '{{ postgres_ha_metrics_exporter_cont_name }}'
+        tags: [ 'postgres-metrics', 'perf']
+        port: '{{ postgres_ha_metrics_exporter_cont_port }}'
+        address: '{{ ansible_local.wireguard.address }}'
+        checks:
+          - id: '{{ postgres_ha_metrics_exporter_cont_name }}-status'
+            name: 'PostgreSQL Metrics exporter'
+            type: 'tcp'
+            tcp: 'localhost:{{ postgres_ha_metrics_exporter_cont_port }}'
+      - name: 'postgres-perf-metrics'
+        id:   '{{ postgres_ha_perf_metrics_exporter_cont_name }}'
+        tags: [ 'postgres-metrics', 'perf']
+        port: '{{ postgres_ha_perf_metrics_exporter_cont_port }}'
+        address: '{{ ansible_local.wireguard.address }}'
+        disabled: '{{ postgres_ha_perf_metrics_exporter_disabled | to_json }}'
+        checks:
+          - id: '{{ postgres_ha_perf_metrics_exporter_cont_name }}-status'
+            name: 'PostgreSQL Metrics exporter'
+            type: 'tcp'
+            tcp: 'localhost:{{ postgres_ha_perf_metrics_exporter_cont_port }}'
+

templates/docker-compose.yml.j2

@@ -40,6 +40,27 @@ services:
         '-U', '{{ postgres_ha_admin_user }}'
       ]
 
+  metrics-exporter:
+    image: '{{ postgres_ha_metrics_exporter_cont_image }}'
+    container_name: '{{ postgres_ha_metrics_exporter_cont_name }}'
+    environment:
+      DATA_SOURCE_URI:  '{{ postgres_ha_cont_name }}:{{ postgres_ha_cont_port }}/{{ postgres_ha_db_name }}?sslmode=disable'
+      DATA_SOURCE_USER: '{{ postgres_ha_admin_user }}'
+      DATA_SOURCE_PASS: '{{ postgres_ha_admin_pass }}'
+    ports:
+      - '{{ postgres_ha_metrics_exporter_cont_port }}:{{ postgres_ha_metrics_exporter_cont_port }}'
+
+{% if not postgres_ha_perf_metrics_exporter_disabled %}
+  perf-metrics-exporter:
+    image: '{{ postgres_ha_perf_metrics_exporter_cont_image }}'
+    container_name: '{{ postgres_ha_perf_metrics_exporter_cont_name }}'
+    environment:
+      DSN:"postgresql://{{ postgres_ha_cont_name }}:{{ postgres_ha_cont_port }}@{{ postgres_ha_cont_name }}:{{postgres_ha_cont_port }}/{{ postgres_ha_db_name }}?connect_timeout=1&statement_timeout=30000&sslmode=disable"
+      LISTEN:"0.0.0.0:{{ postgres_ha_perf_metrics_exporter_cont_port }}"
+    ports:
+      - '{{ postgres_ha_perf_metrics_exporter_cont_port }}:{{ postgres_ha_perf_metrics_exporter_cont_port }}'
+{% endif %}
+
 {% if postgres_ha_cont_networks != [] %}
 networks:
 {% for network in postgres_ha_cont_networks %}

templates/init/alter_system.sql

@@ -2,3 +2,7 @@
 {% for key,val in postgres_ha_alter_system_settings.items() %}
 ALTER SYSTEM SET {{ key }} = '{{ val }}';
 {% endfor %}
+{% if not postgres_ha_perf_metrics_exporter_disabled %}
+CREATE extension pg_stat_statements;
+ALTER SYSTEM SET shared_preload_libraries = 'pg_stat_statements';
+{% endif %}