From fe19e7a514f8d780a0f42eccb24050bf883fb709 Mon Sep 17 00:00:00 2001
From: Piotr Parczewski <piotr@stackhpc.com>
Date: Wed, 26 Mar 2025 15:45:15 +0100
Subject: [PATCH] Upgrade Prometheus to v3

Depends-on: https://review.opendev.org/c/openstack/kolla/+/945604

Change-Id: I6dcee9c503fd67127d5ea611691e206921b1a8a0
---
 ansible/roles/prometheus/defaults/main.yml    |  4 +-
 ansible/roles/prometheus/tasks/upgrade.yml    | 38 +++++++++++++++++++
 ...ade-prometheus-to-v3-bdf73866e7a93194.yaml | 14 +++++++
 3 files changed, 54 insertions(+), 2 deletions(-)
 create mode 100644 releasenotes/notes/upgrade-prometheus-to-v3-bdf73866e7a93194.yaml

diff --git a/ansible/roles/prometheus/defaults/main.yml b/ansible/roles/prometheus/defaults/main.yml
index 943648752c..6f1b853a06 100644
--- a/ansible/roles/prometheus/defaults/main.yml
+++ b/ansible/roles/prometheus/defaults/main.yml
@@ -348,7 +348,7 @@ prometheus_blackbox_exporter_endpoints_custom: []
 ####################
 prometheus_tag: "{{ openstack_tag }}"
 
-prometheus_server_image: "{{ docker_registry ~ '/' if docker_registry else '' }}{{ docker_namespace }}/{{ docker_image_name_prefix }}prometheus-v2-server"
+prometheus_server_image: "{{ docker_registry ~ '/' if docker_registry else '' }}{{ docker_namespace }}/{{ docker_image_name_prefix }}prometheus-server"
 prometheus_server_tag: "{{ prometheus_tag }}"
 prometheus_server_image_full: "{{ prometheus_server_image }}:{{ prometheus_server_tag }}"
 
@@ -404,7 +404,7 @@ prometheus_server_default_volumes:
   - "{{ node_config_directory }}/prometheus-server/:{{ container_config_directory }}/:ro"
   - "/etc/localtime:/etc/localtime:ro"
   - "{{ '/etc/timezone:/etc/timezone:ro' if ansible_facts.os_family == 'Debian' else '' }}"
-  - "prometheus_v2:/var/lib/prometheus"
+  - "prometheus:/var/lib/prometheus"
   - "kolla_logs:/var/log/kolla/"
 prometheus_mysqld_exporter_default_volumes:
   - "{{ node_config_directory }}/prometheus-mysqld-exporter/:{{ container_config_directory }}/:ro"
diff --git a/ansible/roles/prometheus/tasks/upgrade.yml b/ansible/roles/prometheus/tasks/upgrade.yml
index 49edff81e3..8e0fce445c 100644
--- a/ansible/roles/prometheus/tasks/upgrade.yml
+++ b/ansible/roles/prometheus/tasks/upgrade.yml
@@ -1,6 +1,44 @@
 ---
 - import_tasks: config.yml
 
+# NOTE(mnasiadka): Remove me in 2025.2
+- name: Check for the existence of Prometheus v2 container volume
+  become: true
+  stat:
+    path: "{{ container_engine_volumes_path }}/prometheus_v2/_data"
+  register: prometheus_v2_data
+
+- name: Migrate Prometheus volume
+  when: prometheus_v2_data.stat.exists
+  block:
+    - name: Gracefully stop Prometheus
+      become: true
+      kolla_container:
+        name: "{{ prometheus_services['prometheus-server'].container_name }}"
+        action: "stop_and_remove_container"
+        common_options: "{{ docker_common_options }}"
+        ignore_missing: true
+
+    - name: Create new Prometheus v3 volume
+      become: true
+      kolla_container:
+        action: "create_volume"
+        name: "prometheus"
+        common_options: "{{ docker_common_options }}"
+
+    - name: Move _data from old to new volume
+      become: true
+      command: "mv {{ container_engine_volumes_path }}/prometheus_v2/_data {{ container_engine_volumes_path }}/prometheus/"
+      args:
+        removes: "{{ container_engine_volumes_path }}/prometheus_v2/_data"
+
+    - name: Remove old Prometheus v2 volume
+      become: true
+      kolla_container:
+        action: "remove_volume"
+        name: "prometheus_v2"
+        common_options: "{{ docker_common_options }}"
+
 - import_tasks: check-containers.yml
 
 - name: Flush handlers
diff --git a/releasenotes/notes/upgrade-prometheus-to-v3-bdf73866e7a93194.yaml b/releasenotes/notes/upgrade-prometheus-to-v3-bdf73866e7a93194.yaml
new file mode 100644
index 0000000000..392f0dee9f
--- /dev/null
+++ b/releasenotes/notes/upgrade-prometheus-to-v3-bdf73866e7a93194.yaml
@@ -0,0 +1,14 @@
+---
+features:
+  - |
+    Updates Prometheus version to v3.2.1.
+upgrade:
+  - |
+    Prometheus will be upgraded from v2 to v3 - which introduces minor breaking
+    changes. Make sure there's version 2.5.5 or later running before attempting
+    an upgrade. Read the official migration guide for more details here:
+    https://prometheus.io/docs/prometheus/3.0/migration/. Container's name and
+    volume name change back to simply ``prometheus_server`` and ``prometheus``,
+    respectively. The upgrade preserves the old data from ``prometheus_v2``
+    volume, but will leave it behind if the volume name has been customised by
+    the operator.