prometheus: add support for installing webhook server

roles/prometheus/defaults/main.yml

@@ -7,5 +7,6 @@ prometheus_install_grafana: false
 prometheus_hcloud_relabel_configs: []
 
 prometheus_install_alertmanager: true
+prometheus_install_webhook: false
 
 alertmanager_storage_retention: "{{ prometheus_storage_retention }}"

roles/prometheus/meta/argument_specs.yml

@@ -51,6 +51,11 @@ argument_specs:
         type: bool
         required: false
         default: true
+      prometheus_install_webhook:
+        description: If true, installs webhook server in the same docker network as prometheus and configures it
+        type: bool
+        required: false
+        default: false
 
       alertmanager_storage_retention:
         description: Period of time for which alertmanager data is stored for. A number followed by unit (s, m, h, d, w, y). Passed directly to alertmanager role
@@ -58,6 +63,47 @@ argument_specs:
         required: false
         default: "{{ prometheus_storage_retention | default('3650d') }}"
 
+      prometheus_webhook_handlers:
+        description: List of webhook server handlers
+        type: list
+        required: "{{ prometheus_install_webhook }}"
+        elements: dict
+        options:
+          id:
+            description: specifies the ID of your hook. This value is used to create the HTTP endpoint
+            type: str
+            required: true
+          execute-command:
+            description: specifies the command that should be executed when the hook is triggered
+            type: str
+            required: true
+          command-working-directory:
+            description: specifies the working directory that will be used for the script when it's executed
+            type: str
+            required: false
+          pass-arguments-to-command:
+            description: >
+              specifies the list of arguments that will be passed to the
+              command. See for more info:
+              https://github.com/adnanh/webhook/blob/master/docs/Referencing-Request-Values.md
+            type: list
+            required: false
+            elements: dict
+            options:
+              source:
+                description: Source of the argument. Use `string` to specify argument here.
+                type: str
+                required: true
+                choices:
+                  - string
+                  - header
+                  - url
+                  - request
+                  - payload
+              name:
+                description: Argument if source is string, otherwise the source attribute name.
+                type: str
+                required: true
 
       # All options after this will be passed directly to the container role
       docker_service_suffix:

roles/prometheus/tasks/main.yml

@@ -31,6 +31,20 @@
       - name: prometheus
   when: prometheus_install_alertmanager
 
+- name: Webhook container for prometheus
+  include_role:
+    name: container
+  vars:
+    docker_service: prometheus_webhook
+    docker_image: thecatlady/webhook
+    reverse_proxy_type: none
+    docker_mounts:
+      - template: webhooks.yaml
+        path: /config/hooks.yml
+    docker_networks:
+      - name: prometheus
+  when: prometheus_install_webhook
+
 - name: Grafana container for prometheus
   include_role: 
     name: grafana

roles/prometheus/templates/webhooks.yaml.j2

@@ -0,0 +1,5 @@
+---
+
+{% for item in prometheus_webhook_handlers %}
+- {{ item }}
+{% endfor %}