Merge "Add Prometheus 2.x deployment"

ansible/roles/prometheus/defaults/main.yml

@@ -113,13 +113,20 @@ prometheus_mysql_exporter_database_user: "{% if use_preconfigured_databases | bo
 # For a list of modules see the alertmanager config.
 prometheus_blackbox_exporter_endpoints: []
 
+####################
+# Compatibility
+####################
+
+# Whether to keep using Prometheus server v1 (due to no data-preserving migration path to v2)
+prometheus_use_v1: no
+
 ####################
 # Docker
 ####################
 prometheus_install_type: "{{ kolla_install_type }}"
 prometheus_tag: "{{ openstack_tag }}"
 
-prometheus_server_image: "{{ docker_registry ~ '/' if docker_registry else '' }}{{ docker_namespace }}/{{ kolla_base_distro }}-{{ prometheus_install_type }}-prometheus-server"
+prometheus_server_image: "{{ docker_registry ~ '/' if docker_registry else '' }}{{ docker_namespace }}/{{ kolla_base_distro }}-{{ prometheus_install_type }}-{% if not prometheus_use_v1 | bool %}prometheus-v2-server{% else %}prometheus-server{% endif %}"
 prometheus_server_tag: "{{ prometheus_tag }}"
 prometheus_server_image_full: "{{ prometheus_server_image }}:{{ prometheus_server_tag }}"
 
@@ -175,7 +182,7 @@ 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_os_family == 'Debian' else '' }}"
-  - "prometheus:/var/lib/prometheus"
+  - "{{ 'prometheus_v2' if not prometheus_use_v1 | bool else 'prometheus' }}:/var/lib/prometheus"
   - "kolla_logs:/var/log/kolla/"
 prometheus_haproxy_exporter_default_volumes:
   - "{{ node_config_directory }}/prometheus-haproxy-exporter/:{{ container_config_directory }}/:ro"

ansible/roles/prometheus/templates/prometheus-server.json.j2

@@ -1,5 +1,9 @@
 {
+{% if not prometheus_use_v1 | bool %}
+    "command": "/opt/prometheus/prometheus --config.file /etc/prometheus/prometheus.yml --web.listen-address {{ api_interface_address | put_address_in_context('url') }}:{{ prometheus_port }} --web.external-url={{ internal_protocol }}://{{ kolla_internal_fqdn | put_address_in_context('url') }}:{{ prometheus_port }} --storage.tsdb.path /var/lib/prometheus{% if prometheus_cmdline_extras %} {{ prometheus_cmdline_extras }}{% endif %}",
+{% else %}
     "command": "/opt/prometheus/prometheus -config.file /etc/prometheus/prometheus.yml -web.listen-address {{ api_interface_address | put_address_in_context('url') }}:{{ prometheus_port }} -web.external-url={{ internal_protocol }}://{{ kolla_internal_fqdn | put_address_in_context('url') }}:{{ prometheus_port }} -log.format logger:stdout -storage.local.path /var/lib/prometheus{% if prometheus_cmdline_extras %} {{ prometheus_cmdline_extras }}{% endif %}",
+{% endif %}
     "config_files": [
         {
             "source": "{{ container_config_directory }}/prometheus.yml",

doc/source/reference/logging-and-monitoring/prometheus-guide.rst

@@ -20,6 +20,30 @@ and change the following:
 
    enable_prometheus: "yes"
 
+This will, by default, deploy Prometheus version 2.x. Since Prometheus 1.x data
+is not compatible with Prometheus 2.x and no automatic data migration is
+provided, any previous Prometheus 1.x deployment will be replaced and all its
+stored metrics will become inacessible (but still available in the old data
+volume: ``prometheus``; the new data volume defaults to ``prometheus_v2``).
+If you rely on Prometheus only as e.g. a source of alert notifications (in pair
+with Alertmanager), it might not be worth migrating old metrics and they could
+be discarded. Otherwise, it's either possible to use
+`remote storage <https://prometheus.io/docs/prometheus/latest/storage/#remote-storage-integrations>`_
+or scrape Kolla's Prometheus ``/federate`` endpoint with an external system.
+However, if you want to stay on 1.x series, set the following variable:
+
+.. code-block:: yaml
+
+   prometheus_use_v1: yes
+
+In order to remove leftover volume containing Prometheus 1.x data, execute:
+
+.. code-block:: console
+
+   docker volume rm prometheus
+
+on all hosts wherever Prometheus was previously deployed.
+
 Extending the default command line options
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 

etc/kolla/globals.yml

@@ -696,6 +696,9 @@
 #  - host1:port1
 #  - host2:port2
 
+# Whether to keep using Prometheus server v1 (due to no data-preserving migration path to v2)
+#prometheus_use_v1: no
+
 #########
 # Freezer
 #########

releasenotes/notes/add-prometheus-v2-9f10c79986d3faf3.yaml

@@ -0,0 +1,17 @@
+---
+features:
+  - |
+    Prometheus version 2.x deployment added. This version is enabled by
+    default and replaces a forward-incompatible version 1.x. A variable
+    ``prometheus_use_v1`` can be set to ``yes`` to preserve version
+    1.x deployment with its data. Otherwise, Prometheus will start with
+    a new volume, ignoring all previously collected metrics.
+upgrade:
+  - |
+    New Prometheus version ignores previously stored metrics. If you
+    want to keep using 1.x with the old data, set ``prometheus_use_v1``
+    variable to ``yes``. The old data is not removed, please read the
+    docs for details. Please also make sure you adapt changes in command
+    line options if they were ever customized in your environment because
+    Prometheus 2.x has different syntax (``--option`` with double dashes
+    instead of ``-option``).