Prepare directory for mod_prometheus

mod_prometheus/README.md

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+mod_prometheus - Prometheus metrics
+===================================
+
+- Requires: ejabberd git commit xxx or higher
+- Author: [Pouriya Jahanbakhsh](https://github.com/pouriya)
+
+This module provides a web page with metrics suitable
+for [Prometheus](https://prometheus.io/),
+using the [prometheus](https://github.com/deadtrickster/prometheus.erl) erlang library.
+
+
+Options
+-------
+
+The configurable options are:
+
+- `mnesia: true | false`
+
+  Enable mnesia metrics or not.
+  Default: `false`
+
+- `vm: [metric: true | false, ...]`
+
+  Enable some Erlang Virtual Machine metrics.
+  Available ones are:
+  `memory`, `system_info`, `statistics`, `distribution`, `microstate_accounting`.
+  For details please consult
+  [prometheus.erl collectors](https://github.com/deadtrickster/prometheus.erl?tab=readme-ov-file#erlang-vm--otp-collectors).
+  Default: `[]`
+
+- `hooks: [Hook]`
+
+  List of hooks to investigate.
+  Default is an empty list: `[]`
+
+  Each Hook is:
+  - `hook: atom()`: the name of the hook
+  - `type: counter | histogram`
+  - `help: "Explanation"`
+  - `stanza_label: true | false`
+  - `host_label: true | false`
+  - `collect: all | [Callback]`
+      where each Callback is:
+      - `module: atom()`
+      - `function: atom()`
+      - `help: "Explanation"`
+      - `buckets: [integer()]`
+
+Quick Start Guide
+-----------------
+
+### Install module
+
+1. Start ejabberd
+
+1. Download dependencies, compile and install this module:
+   ```sh
+   ejabberdctl module_install mod_prometheus
+   ```
+1. Check ejabberd provides metrics in the URL: `http://localhost:5289/metrics/`
+
+### Start Prometheus and Grafana
+
+Start Prometheus and Grafana, for example using Podman or Docker:
+
+```sh
+cd example
+podman-compose up
+# or
+# docker-compose up
+```
+
+### Test Prometheus
+
+1. Open in web browser `http://localhost:9090/`
+
+1. Enter example query: `erlang_mnesia_tablewise_size{table="muc_online_room"}`
+
+### Setup Grafana
+
+1. Open in web browser `http://localhost:3000/`
+
+1. Login with username `admin` and password `admin`
+
+1. Add data source: Prometheus
+   - Connection: `http://host.docker.internal:9090` (or `http://prometheus:9090`, or something similar)
+   - Click `Save & test`
+
+1. Create your first dashboard
+   - Import dashboard
+   - Upload dashboard JSON file: you can try `ejabberd-dash.json`

mod_prometheus/conf/mod_prometheus.yml

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+listen:
+  -
+    port: 5289
+    ip: "::"
+    module: ejabberd_http
+    request_handlers:
+      /metrics: mod_prometheus
+
+modules:
+  mod_prometheus:
+    mnesia: true
+    vm:
+      memory: true
+      system_info: true
+      statistics: false
+      distribution: false
+      microstate_accounting: false
+    hooks:
+      # Histogram for a hook:
+      - hook: user_send_packet
+        type: histogram
+        help: "Handling of sent messages duration in millisecond"
+        stanza_label: true
+        host_label: true
+      # Counter for a hook:
+      - hook: user_send_packet
+        type: counter
+        help: "Number of sent messages"
+      # Histograms only for some callbacks of a hook:
+      - hook: user_send_packet
+        type: histogram
+        host_label: true
+        collect:
+          - module: mod_carboncopy
+            function: user_send_packet
+            help: "Handling of carbon copied messages in millisecond"
+          - module: mod_mam
+            function: user_send_packet
+            help: "Handling of MAM messages in millisecond"
+            buckets:
+              - 10
+              - 100
+              - 750
+              - 1000
+              - 1500

mod_prometheus/example/docker-compose.yml

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+version: '3.7'
+
+services:
+
+  prometheus:
+    image: docker.io/prom/prometheus
+    container_name: prometheus
+    ports:
+      - "9090:9090"
+    volumes:
+      - ./prometheus.yml:/etc/prometheus/prometheus.yml
+
+  grafana:
+    image: docker.io/grafana/grafana-enterprise
+    container_name: grafana
+    ports:
+      - "3000:3000"