API Stability Guarantees

Prometheus promises API stability within a major version, and strives to avoid breaking changes for key features. Some features, which are cosmetic, still under development, or depend on 3rd party services, are not covered by this.

Things considered stable for 3.x:

• The query language and data model
• Alerting and recording rules
• The ingestion exposition format
• v1 HTTP API (used by dashboards and UIs)
• Configuration file format (minus the service discovery remote read/write, see below)
• Rule/alert file format
• Console template syntax and semantics
• Remote write sending, per the 1.0 specification and receiving
• Agent mode
• OTLP receiver endpoint

Things considered unstable for 3.x:

• Any feature listed as experimental or subject to change, including:
  • The double_exponential_smoothing PromQL function
  • Remote read and the remote read endpoint
• Server-side HTTPS and basic authentication
• Service discovery integrations, with the exception of static_configs, file_sd_configs and http_sd_config
• Go APIs of packages that are part of the server
• HTML generated by the web UI
• The metrics in the /metrics endpoint of Prometheus itself
• Exact on-disk format. Potential changes however, will be forward compatible and transparently handled by Prometheus
• The format of the logs

Prometheus 2.x stability guarantees can be found in the 2.x documentation.

As long as you are not using any features marked as experimental/unstable, an upgrade within a major version can usually be performed without any operational adjustments and very little risk that anything will break. Any breaking changes will be marked as CHANGE in release notes.

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