Add prometheus auth-type to turn-off authentication (#8356)

Also this PR moves the original doc from cookbook to
MinIO repo under docs/metrics/prometheus/

Fixes #8323

cmd/metrics-router.go

@@ -17,6 +17,9 @@
 package cmd
 
 import (
+	"os"
+	"strings"
+
 	"github.com/gorilla/mux"
 )
 
@@ -24,9 +27,28 @@ const (
 	prometheusMetricsPath = "/prometheus/metrics"
 )
 
+// Standard env prometheus auth type
+const (
+	EnvPrometheusAuthType = "MINIO_PROMETHEUS_AUTH_TYPE"
+)
+
+type prometheusAuthType string
+
+const (
+	prometheusJWT    prometheusAuthType = "jwt"
+	prometheusPublic prometheusAuthType = "public"
+)
+
 // registerMetricsRouter - add handler functions for metrics.
 func registerMetricsRouter(router *mux.Router) {
 	// metrics router
 	metricsRouter := router.NewRoute().PathPrefix(minioReservedBucketPath).Subrouter()
-	metricsRouter.Handle(prometheusMetricsPath, AuthMiddleware(metricsHandler()))
+
+	authType := strings.ToLower(os.Getenv(EnvPrometheusAuthType))
+	switch prometheusAuthType(authType) {
+	case prometheusPublic:
+		metricsRouter.Handle(prometheusMetricsPath, metricsHandler())
+	default:
+		metricsRouter.Handle(prometheusMetricsPath, AuthMiddleware(metricsHandler()))
+	}
 }

docs/metrics/prometheus/README.md

@@ -0,0 +1,135 @@
+# How to monitor MinIO server with Prometheus [![Slack](https://slack.min.io/slack?type=svg)](https://slack.min.io)
+
+[Prometheus](https://prometheus.io) is a cloud-native monitoring platform, built originally at SoundCloud. Prometheus offers a multi-dimensional data model with time series data identified by metric name and key/value pairs. The data collection happens via a pull model over HTTP/HTTPS. Targets to pull data from are discovered via service discovery or static configuration.
+
+MinIO exports Prometheus compatible data by default as an authorized endpoint at `/minio/prometheus/metrics`. Users looking to monitor their MinIO instances can point Prometheus configuration to scrape data from this endpoint.
+
+This document explains how to setup Prometheus and configure it to scrape data from MinIO servers.
+
+**Table of Contents**
+
+- [Prerequisites](#prerequisites)
+    - [1. Download Prometheus](#1-download-prometheus)
+    - [2. Configure authentication type for Prometheus metrics](#2-configure-authentication-type-for-prometheus-metrics)
+    - [3. Configuring Prometheus](#3-configuring-prometheus)
+        - [3.1 Authenticated Prometheus config](#31-authenticated-prometheus-config)
+        - [3.2 Public Prometheus config](#32-public-prometheus-config)
+    - [4. Update `scrape_configs` section in prometheus.yml](#4-update-scrapeconfigs-section-in-prometheusyml)
+    - [5. Start Prometheus](#5-start-prometheus)
+- [List of metrics exposed by MinIO](#list-of-metrics-exposed-by-minio)
+
+## Prerequisites
+To get started with MinIO, refer [MinIO QuickStart Document](https://docs.min.io/docs/minio-quickstart-guide). Follow below steps to get started with MinIO monitoring using Prometheus.
+
+### 1. Download Prometheus
+
+[Download the latest release](https://prometheus.io/download) of Prometheus for your platform, then extract it
+
+```sh
+tar xvfz prometheus-*.tar.gz
+cd prometheus-*
+```
+
+Prometheus server is a single binary called `prometheus` (or `prometheus.exe` on Microsoft Windows). Run the binary and pass `--help` flag to see available options
+
+```sh
+./prometheus --help
+usage: prometheus [<flags>]
+
+The Prometheus monitoring server
+
+. . .
+
+```
+
+Refer [Prometheus documentation](https://prometheus.io/docs/introduction/first_steps/) for more details.
+
+### 2. Configure authentication type for Prometheus metrics
+
+MinIO supports two authentication modes for Prometheus either `jwt` or `public`, by default MinIO runs in `jwt` mode. To allow public access without authentication for prometheus metrics set environment as follows.
+
+```
+export MINIO_PROMETHEUS_AUTH_TYPE="public"
+minio server ~/test
+```
+
+### 3. Configuring Prometheus
+
+#### 3.1 Authenticated Prometheus config
+
+> If MinIO is configured to expose metrics without authentication, you don't need to use `mc` to generate prometheus config. You can skip reading further and move to 3.2 section.
+
+The Prometheus endpoint in MinIO requires authentication by default. Prometheus supports a bearer token approach to authenticate prometheus scrape requests, override the default Prometheus config with the one generated using mc. To generate a Prometheus config for an alias, use [mc](https://docs.min.io/docs/minio-client-quickstart-guide) as follows `mc admin prometheus generate <alias>`.
+
+The command will generate the `scrape_configs` section of the prometheus.yml as follows:
+
+```yaml
+scrape_configs:
+- job_name: minio-job
+  bearer_token: <secret>
+  metrics_path: /minio/prometheus/metrics
+  scheme: http
+  static_configs:
+  - targets: ['localhost:9000']
+```
+
+#### 3.2 Public Prometheus config
+
+If Prometheus endpoint authentication type is set to `public`. Following prometheus config is sufficient to start scraping metrics data from MinIO.
+
+```yaml
+scrape_configs:
+- job_name: minio-job
+  metrics_path: /minio/prometheus/metrics
+  scheme: http
+  static_configs:
+  - targets: ['localhost:9000']
+```
+
+### 4. Update `scrape_configs` section in prometheus.yml
+
+To authorize every scrape request, copy and paste the generated `scrape_configs` section in the prometheus.yml and restart the Prometheus service.
+
+### 5. Start Prometheus
+
+Start (or) Restart Prometheus service by running
+
+```sh
+./prometheus --config.file=prometheus.yml
+```
+
+Here `prometheus.yml` is the name of configuration file. You can now see MinIO metrics in Prometheus dashboard. By default Prometheus dashboard is accessible at `http://localhost:9090`.
+
+## List of metrics exposed by MinIO
+
+MinIO server exposes the following metrics on `/minio/prometheus/metrics` endpoint. All of these can be accessed via Prometheus dashboard. The full list of exposed metrics along with their definition is available in the demo server at https://play.min.io:9000/minio/prometheus/metrics
+
+- standard go runtime metrics prefixed by `go_`
+- process level metrics prefixed with `process_`
+- prometheus scrap metrics prefixed with `promhttp_`
+
+- `minio_disk_storage_used_bytes` : Total byte count of disk storage used by current MinIO server instance
+- `minio_http_requests_duration_seconds_bucket` : Cumulative counters for all the request types (HEAD/GET/PUT/POST/DELETE) in different time brackets
+- `minio_http_requests_duration_seconds_count` : Count of current number of observations i.e. total HTTP requests (HEAD/GET/PUT/POST/DELETE)
+- `minio_http_requests_duration_seconds_sum` : Current aggregate time spent servicing all HTTP requests (HEAD/GET/PUT/POST/DELETE) in seconds
+- `minio_network_received_bytes_total` : Total number of bytes received by current MinIO server instance
+- `minio_network_sent_bytes_total` : Total number of bytes sent by current MinIO server instance
+- `minio_offline_disks` : Total number of offline disks for current MinIO server instance
+- `minio_total_disks` : Total number of disks for current MinIO server instance
+- `minio_disk_storage_available_bytes` : Current storage space available to MinIO server in bytes
+- `minio_disk_storage_total_bytes` : Total storage space available to MinIO server in bytes
+- `process_start_time_seconds` : Start time of MinIO server since unix epoc hin seconds
+
+If you're running MinIO gateway, disk/storage information is not exposed. Only following metrics are available
+
+- `minio_http_requests_duration_seconds_bucket` : Cumulative counters for all the request types (HEAD/GET/PUT/POST/DELETE) in different time brackets
+- `minio_http_requests_duration_seconds_count` : Count of current number of observations i.e. total HTTP requests (HEAD/GET/PUT/POST/DELETE)
+- `minio_http_requests_duration_seconds_sum` : Current aggregate time spent servicing all HTTP requests (HEAD/GET/PUT/POST/DELETE) in seconds
+- `minio_network_received_bytes_total` : Total number of bytes received by current MinIO server instance
+- `minio_network_sent_bytes_total` : Total number of bytes sent by current MinIO server instance
+- `process_start_time_seconds` : Start time of MinIO server since unix epoch in seconds
+
+For MinIO instances with [`caching`](https://github.com/minio/minio/tree/master/docs/disk-caching) enabled, these additional metrics are available.
+
+- `minio_disk_cache_storage_bytes` : Total byte count of cache capacity available for current MinIO server instance
+- `minio_disk_cache_storage_free_bytes` : Total byte count of free cache available for current MinIO server instance