# Prometheus Rust client library
[](https://github.com/prometheus/client_rust/actions)
[](https://crates.io/crates/prometheus-client)
[](https://docs.rs/prometheus-client)
[Rust](https://github.com/rust-lang/) client library implementation of the [Open
Metrics specification](https://github.com/OpenObservability/OpenMetrics). Allows
developers to instrument applications and thus enables operators to monitor said
applications with monitoring systems like [Prometheus](https://prometheus.io/).
**Documentation**: https://docs.rs/prometheus-client/
## Goals
- No `unsafe`. Don't use unsafe Rust within the library itself.
- Type safe. Leverage Rust's type system to catch common instrumentation
mistakes at compile time.
- Fast. Don't force users to worry about the performance impact of
instrumentation. Instead encourage users to instrument often and extensively.
## Specification Compliance
Below is a list of properties where this client library implementation lags
behind the Open Metrics specification. Not being compliant with all requirements
(`MUST` and `MUST NOT`) of the specification is considered a bug and likely to
be fixed in the future. Contributions in all forms are most welcome.
- State set metric.
- Enforce "A Histogram MetricPoint MUST contain at least one bucket".
- Enforce "A MetricFamily MUST have a [...] UNIT metadata".
- Enforce "MetricFamily names [...] MUST be unique within a MetricSet."
- Enforce "Names SHOULD be in snake_case".
- Enforce "MetricFamily names beginning with underscores are RESERVED and MUST
NOT be used unless specified by this standard".
- Enforce "Exposers SHOULD avoid names that could be confused with the suffixes
that text format sample metric names use".
- Gauge histogram metric.
- Allow "A MetricPoint in a Metric with the type [Counter, Histogram] SHOULD have a Timestamp
value called Created".
- Summary metric.
## Related Libraries
- [rust-prometheus](https://github.com/tikv/rust-prometheus/): See [tikv/rust-prometheus/#392](https://github.com/tikv/rust-prometheus/issues/392) for a high-level comparison.
## License
Licensed under either of
* Apache License, Version 2.0 ([LICENSE-APACHE](LICENSE-APACHE) or http://www.apache.org/licenses/LICENSE-2.0)
* MIT license ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT)
at your option.
#### Contribution
Unless you explicitly state otherwise, any contribution intentionally submitted
for inclusion in the work by you, as defined in the Apache-2.0 license, shall be
dual licensed as above, without any additional terms or conditions.