[opensourcedex]

Prometheus is a free, open source databases project written in Go and released under Apache-2.0. It has 66,106 GitHub stars, 10,840 forks and 890 open issues, and was last pushed 9 hours ago. On this registry it ranks #2 of 81 tracked projects in Databases, with 5 head-to-head comparisons available. It gained 53 stars over the last 6 tracked days.

Prometheus — Open source metrics collection, storage, and alerting

What is Prometheus?

What it is

Prometheus is an open-source monitoring system and time series database, part of the Cloud Native Computing Foundation ecosystem. It collects metrics from configured targets at defined intervals, evaluates alerting rules, and visualizes results. Designed for reliability in dynamic environments, it operates without reliance on distributed storage, ensuring each server node functions independently.

Prometheus solves the problem of monitoring ephemeral, scalable infrastructure by providing a pull-based metrics collection model, a flexible query language (PromQL), and native support for service discovery. This enables teams to observe system health and performance in real time across containerized and microservices deployments, where traditional push-based or static monitoring tools struggle with discovery and scalability.

Key capabilities

  • Multi-dimensional data model using metric names and key/value label pairs
  • PromQL, a query language for filtering, aggregating, and joining time series data
  • Pull-based metrics scraping via HTTP endpoints with optional push gateway for batch jobs
  • Automatic target discovery through service discovery mechanisms (e.g., Kubernetes, Consul) or static configuration
  • Alerting via Alertmanager for routing and deduplicating notifications
  • Built-in web UI for graphing metrics and exploring data
  • Hierarchical and horizontal federation for aggregating data across multiple Prometheus servers

Who uses it and how

  • DevOps and SRE teams deploy Prometheus to monitor Kubernetes clusters, leveraging its service discovery to auto-detect pods and services
  • Platform engineers use federation to aggregate metrics from regional Prometheus instances into a central query layer
  • Developers integrate the push gateway to submit batch job metrics (e.g., ETL tasks) that cannot expose HTTP endpoints
  • Infrastructure teams configure Alertmanager to route critical alerts to PagerDuty, Slack, or email based on severity and team ownership
  • Observability engineers build dashboards in Grafana using Prometheus as a data source for system and application metrics

Getting started

Precompiled binaries are available from prometheus.io/download. Docker images run via docker run --name prometheus -d -p 127.0.0.1:9090:9090 prom/prometheus. Building from source requires Go and Node.js; binaries are installed with go install github.com/prometheus/prometheus/cmd/... and run with prometheus --config.file=your_config.yml.

When to use it — and when not to

Prometheus replaces proprietary monitoring tools like Nagios or Zabbix for cloud-native environments but lacks built-in log aggregation or distributed tracing—these require integration with tools like Loki or Jaeger. Self-hosting requires managing storage (local disk or remote storage adapter), alert routing (via Alertmanager), and configuration scaling (e.g., federation, rule grouping). It is unsuitable for high-cardinality, low-frequency data or use cases needing long-term retention without external storage backend configuration.

project readme (upstream, from github) — read inline


Prometheus

Visit prometheus.io for the full documentation, examples and guides.

CI [Docker Repository on Quay][quay] [Docker Pulls][hub] CII Best Practices govulncheck OpenSSF Scorecard CLOMonitor Fuzzing Status

Prometheus, a Cloud Native Computing Foundation project, is a systems and service monitoring system. It collects metrics from configured targets at given intervals, evaluates rule expressions, displays the results, and can trigger alerts when specified conditions are observed.

The features that distinguish Prometheus from other metrics and monitoring systems are:

  • A multi-dimensional data model (time series defined by metric name and set of key/value dimensions)
  • PromQL, a powerful and flexible query language to leverage this dimensionality
  • No dependency on distributed storage; single server nodes are autonomous
  • An HTTP pull model for time series collection
  • Pushing time series is supported via an intermediary gateway for batch jobs
  • Targets are discovered via service discovery or static configuration
  • Multiple modes of graphing and dashboarding support
  • Support for hierarchical and horizontal federation

Architecture overview

Architecture overview

Install

There are various ways to install Prometheus.

Precompiled binaries

Precompiled binaries for released versions are available in the download section on prometheus.io. Using the latest production release binary is the recommended way to install Prometheus. See the Installing chapter in the documentation for all the details.

Docker images

Docker images are available on Quay.io or Docker Hub.

You can launch a Prometheus container for trying it out with

docker run --name prometheus -d -p 127.0.0.1:9090:9090 prom/prometheus

Prometheus will now be reachable at .

Building from source

To build Prometheus from source code, you need:

  • Go: Version specified in go.mod or greater.
  • NodeJS: Version specified in .nvmrc or greater.
  • npm: Version 10 or greater (check with npm --version and here).

Start by cloning the repository:

git clone https://github.com/prometheus/prometheus.git
cd prometheus

You can use the go tool to build and install the prometheus and promtool binaries into your GOPATH:

go install github.com/prometheus/prometheus/cmd/...
prometheus --config.file=your_config.yml

However, when using go install to build Prometheus, Prometheus will expect to be able to read its web assets from local filesystem directories under web/ui/static. In order for these assets to be found, you will have to run Prometheus from the root of the cloned repository. Note also that this directory does not include the React UI unless it has been built explicitly using make assets or make build.

An example of the above configuration file can be found here.

You can also build using make build, which will compile in the web assets so that Prometheus can be run from anywhere:

make build
./prometheus --config.file=your_config.yml

The Makefile provides several targets:

  • build: build the prometheus and promtool binaries (includes building and compiling in web assets)
  • test: run the tests
  • test-short: run the short tests
  • format: format the source code
  • vet: check the source code for common errors
  • assets: build the React UI

Service discovery plugins

Prometheus is bundled with many service discovery plugins. You can customize which service discoveries are included in your build using Go build tags.

To exclude service discoveries when building with make build, add the desired tags to the .promu.yml file under build.tags.all:

build:
    tags:
        all:
            - netgo
            - builtinassets
            - remove_all_sd           # Exclude all optional SDs
            - enable_kubernetes_sd    # Re-enable only kubernetes

Then run make build as usual. Alternatively, when using go build directly:

go build -tags "remove_all_sd,enable_kubernetes_sd" ./cmd/prometheus

Available build tags:

  • remove_all_sd - Exclude all optional service discoveries (keeps file_sd, static_sd, and http_sd)
  • enable__sd - Re-enable a specific SD when using remove_all_sd

If you add out-of-tree plugins, which we do not endorse at the moment, additional steps might be needed to adjust the go.mod and go.sum files. As always, be extra careful when loading third party code.

Building the Docker image

You can build a docker image locally with the following commands:

make promu
promu crossbuild -p linux/$(go env GOHOSTARCH)
make common-docker-current-arch

To build for a different architecture, replace $(go env GOHOSTARCH) with one of the architectures in DOCKER_ARCHS from Makefile.common, such as amd64, and run the corresponding make common-docker- target.

The make docker target is intended only for use in our CI system and will not produce a fully working image when run locally.

Using Prometheus as a Go Library

Within the Prometheus project, repositories such as prometheus/common and prometheus/client-golang are designed as re-usable libraries.

The prometheus/prometheus repository builds a stand-alone program and is not designed for use as a library. We are aware that people do use parts as such, and we do not put any deliberate inconvenience in the way, but we want you to be aware that no care has been taken to make it work well as a library. For instance, you may encounter errors that only surface when used as a library.

Remote Write

We are publishing our Remote Write protobuf independently at buf.build.

You can use that as a library:

go get buf.build/gen/go/prometheus/prometheus/protocolbuffers/go@latest

This is experimental.

Prometheus code base

In order to comply with go mod rules, Prometheus release number do not exactly match Go module releases.

For the Prometheus v3.y.z releases, we are publishing equivalent v0.3y.z tags. The y in v0.3y.z is always padded to two digits, with a leading zero if needed.

Therefore, a user that would want to use Prometheus v3.0.0 as a library could do:

go get github.com/prometheus/[email protected]

For the Prometheus v2.y.z releases, we published the equivalent v0.y.z tags.

Therefore, a user that would want to use Prometheus v2.35.0 as a library could do:

go get github.com/prometheus/[email protected]

This solution makes it clear that we might break our internal Go APIs between minor user-facing releases, as breaking changes are allowed in major version zero.

React UI Development

For more information on building, running, and developing on the React-based UI, see the React app's README.md.

More information

readme truncated — read the full docs on github

Frequently asked questions

Is Prometheus free to use?

Prometheus is open source under the Apache-2.0 licence. There is no licence fee and no seat count — you can self-host it or, where the project offers one, pay a vendor for a managed version instead.

What does Prometheus do?

Open source metrics collection, storage, and alerting

What is Prometheus written in?

Prometheus is primarily written in Go. Its source is publicly available at https://github.com/prometheus/prometheus, and it has 66,106 GitHub stars.