Add the doc for metrics (#160)

Author: Noah Hanjun Lee

docs/concepts/metrics.md

@@ -0,0 +1,36 @@
+# Metrics
+
+Gtiploy publishes and exposes metrics that Prometheus can consume at the standard `/metrics` endpoint.
+
+## Configuration
+
+1\. Configure the server:
+
+```
+GITPLOY_PROMETHEUS_AUTH_SECRET=YOUR_SECRET
+```
+
+2\. Configure the prometheus scraper:
+
+```
+global:
+  scrape_interval: 60s
+
+  scrape_configs:
+  - job_name: gitploy
+      authorization:
+        credentials: YOUR_SECRET
+
+      static_configs:
+      - targets: ['domain.com']
+```
+
+## Gitploy Metrics
+
+Gitploy provides the following Gitploy metrics:
+
+* **gitploy_requests_total** <br/> How many HTTP requests processed, partitioned by status code and HTTP method.
+* **gitploy_request_duration_seconds**<br/> The HTTP request latencies in seconds.
+* **gitploy_deployment_count**<br/> The total count of success deployment for each environment, respectively.
+* **gitploy_member_count**<br/> The total count of members.
+* **gitploy_member_limit**<br/> The limit count of members.

internal/server/metrics/metrics.go

@@ -143,7 +143,7 @@ func (c *collector) Collect(ch chan<- prometheus.Metric) {
 					"",
 					"member_count",
 				),
-				"The total count of member.",
+				"The total count of members.",
 				nil,
 				nil,
 			),
@@ -158,7 +158,7 @@ func (c *collector) Collect(ch chan<- prometheus.Metric) {
 					"",
 					"member_limit",
 				),
-				"The limit of count of member.",
+				"The limit count of members.",
 				[]string{"kind"},
 				nil,
 			),

mkdocs.yml

@@ -17,9 +17,10 @@ nav:
     - Deployment: concepts/deployment.md
     - Lock: concepts/lock.md
     - Permission: concepts/permission.md
-    - "Self-hosted Server": concepts/self-hosted-server.md
     - Chatops: concepts/chatops.md
+    - Metrics: concepts/metrics.md
     - License: concepts/license.md
+    - "Self-hosted Server": concepts/self-hosted-server.md
   - Tasks:
     - Installation: tasks/installation.md
     - Database: tasks/database.md