# 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

These are the new set of metrics which will be in effect after `RELEASE.2019-10-16*`. Some of the key changes in this update are listed below.
    - Metrics are bound the respective nodes and is not cluster-wide. Each and every node in a cluster will expose its own metrics.
    - Additional metrics to cover the s3 and internode traffic statistics were added.
    - Metrics that records the http statistics and latencies are labeled to their respective APIs (putobject,getobject etc).
    - Disk usage metrics are distributed and labeled to the respective disk paths.

For more details, please check the `Migration guide for the new set of metrics`

The list of metrics and its definition are as follows. (NOTE: instance here is one MinIO node)

> NOTES:
    > 1. Instance here is one MinIO node.
    > 2. `s3 requests` exclude internode requests.

- standard go runtime metrics prefixed by `go_`
- process level metrics prefixed with `process_`
- prometheus scrape metrics prefixed with `promhttp_`

- `disk_storage_used` : Disk space used by the disk.
- `disk_storage_available`: Available disk space left on the disk.
- `disk_storage_total`: Total disk space on the disk.
- `minio_disks_offline`: Total number of offline disks in current MinIO instance.
- `minio_disks_total`: Total number of disks in current MinIO instance.
- `s3_requests_total`: Total number of s3 requests in current MinIO instance.
- `s3_errors_total`: Total number of errors in s3 requests in current MinIO instance.
- `s3_requests_current`: Total number of active s3 requests in current MinIO instance.
- `internode_rx_bytes_total`: Total number of internode bytes received by current MinIO server instance.
- `internode_tx_bytes_total`: Total number of bytes sent to the other nodes by current MinIO server instance.
- `s3_rx_bytes_total`: Total number of s3 bytes received by current MinIO server instance.
- `s3_tx_bytes_total`: Total number of s3 bytes sent by current MinIO server instance.
- `minio_version_info`: Current MinIO version with commit-id.
- `s3_ttfb_seconds`: Histogram that holds the latency information of the requests.

Apart from above metrics, MinIO also exposes below mode specific metrics

### Cache specific metrics

MinIO Gateway instances enabled with Disk-Caching expose caching related metrics.

- `cache_data_served`: Total number of bytes served from cache.
- `cache_hits_total`: Total number of cache hits.
- `cache_misses_total`: Total number of cache misses.

### Gateway & Cache specific metrics

MinIO Gateway instance exposes metrics related to Gateway communication with the cloud backend (S3, Azure & GCS Gateway).

- `gateway_<gateway_type>_requests`: Total number of GET & HEAD requests made to cloud backend. This metrics has a label `method` that identifies GET & HEAD Requests.
- `gateway_<gateway_type>_bytes_sent`: Total number of bytes sent to cloud backend (in GET & HEAD Requests).
- `gateway_<gateway_type>_bytes_received`: Total number of bytes received from cloud backend (in GET & HEAD Requests).

Note that this is currently only support for Azure, S3 and GCS Gateway.

## Migration guide for the new set of metrics

This migration guide applies for older releases or any releases before `RELEASE.2019-10-23*`

### MinIO disk level metrics - `disk_*`

The migrations include

    - `minio_total_disks` to `minio_disks_total`
    - `minio_offline_disks` to `minio_disks_offline`

### MinIO disk level metrics - `disk_storage_*`

These metrics have one label.

    - `disk`: Holds the disk path

The migrations include

    - `minio_disk_storage_used_bytes` to `disk_storage_used`
    - `minio_disk_storage_available_bytes` to `disk_storage_available`
    - `minio_disk_storage_total_bytes` to `disk_storage_total`

### MinIO network level metrics

These metrics are detailed to cover the s3 and internode network statistics.

The migrations include

    - `minio_network_sent_bytes_total` to `s3_tx_bytes_total` and `internode_tx_bytes_total`
    - `minio_network_received_bytes_total` to `s3_rx_bytes_total` and `internode_rx_bytes_total`

Some of the additional metrics added were

    - `s3_requests_total`
    - `s3_errors_total`
    - `s3_ttfb_seconds`
