loki

Like Prometheus, but for logs.

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Loki: like Prometheus, but for logs.

Loki is a horizontally-scalable, highly-available, multi-tenant log aggregation system inspired by Prometheus.
It is designed to be very cost effective and easy to operate.
It does not index the contents of the logs, but rather a set of labels for each log stream.

Compared to other log aggregation systems, Loki:

  • does not do full text indexing on logs. By storing compressed, unstructured logs and only indexing metadata, Loki is simpler to operate and cheaper to run.
  • indexes and groups log streams using the same labels you’re already using with Prometheus, enabling you to seamlessly switch between metrics and logs using the same labels that you’re already using with Prometheus.
  • is an especially good fit for storing Kubernetes Pod logs. Metadata such as Pod labels is automatically scraped and indexed.
  • has native support in Grafana (needs Grafana v6.0).

A Loki-based logging stack consists of 3 components:

  • Alloy is agent, responsible for gathering logs and sending them to Loki.
  • Loki is the main service, responsible for storing logs and processing queries.
  • Grafana for querying and displaying the logs.

Note that Alloy replaced Promtail in the stack, because Promtail is considered to be feature complete, and future development for logs collection will be in Grafana Alloy.

Loki is like Prometheus, but for logs: we prefer a multidimensional label-based approach to indexing, and want a single-binary, easy to operate system with no dependencies.
Loki differs from Prometheus by focusing on logs instead of metrics, and delivering logs via push, instead of pull.

Getting started

Upgrading

Documentation

Commonly used sections:

Getting Help

If you have any questions or feedback regarding Loki:

Your feedback is always welcome.

Further Reading

Contributing

Refer to CONTRIBUTING.md

Building from source

Loki can be run in a single host, no-dependencies mode using the following commands.

You need an up-to-date version of Go, we recommend using the version found in our Makefile

# Checkout source code
$ git clone https://github.com/grafana/loki
$ cd loki

# Build binary
$ go build ./cmd/loki

# Run executable
$ ./loki -config.file=./cmd/loki/loki-local-config.yaml

Alternatively, on Unix systems you can use make to build the binary, which adds additional arguments to the go build command.

# Build binary
$ make loki

# Run executable
$ ./cmd/loki/loki -config.file=./cmd/loki/loki-local-config.yaml

To build Promtail on non-Linux platforms, use the following command:

$ go build ./clients/cmd/promtail

On Linux, Promtail requires the systemd headers to be installed if
Journal support is enabled.
To enable Journal support the go build tag flag promtail_journal_enabled should be passed

With Journal support on Ubuntu, run with the following commands:

$ sudo apt install -y libsystemd-dev
$ go build --tags=promtail_journal_enabled ./clients/cmd/promtail

With Journal support on CentOS, run with the following commands:

$ sudo yum install -y systemd-devel
$ go build --tags=promtail_journal_enabled ./clients/cmd/promtail

Otherwise, to build Promtail without Journal support, run go build
with CGO disabled:

$ CGO_ENABLED=0 go build ./clients/cmd/promtail

Adopters

Please see ADOPTERS.md for some of the organizations using Loki today.
If you would like to add your organization to the list, please open a PR to add it to the list.

License

Grafana Loki is distributed under AGPL-3.0-only. For Apache-2.0 exceptions, see LICENSING.md.