0.4.0 / 2026-07-10

PromLens is no longer maintained and has been archived. Much of its functionality has been merged into the Prometheus server's "Explain" tab, where it is kept up to date.

• [CHANGE] PromQL: The holt_winters function is now called double_exponential_smoothing, following its rename in Prometheus 3.0. #266
• [CHANGE] Logging: Switch from go-kit/log to Go's standard library log/slog. The log output format has changed. #149
• [CHANGE] Docker images are now also published to GHCR (ghcr.io/prometheus/promlens). #260
• [FEATURE] PromQL: Update the PromQL parser to Prometheus 3.13. This adds support for UTF-8 metric and label names and for all functions added since Prometheus 2.55, e.g. info(), sort_by_label(), mad_over_time(), and the native histogram functions (histogram_avg(), histogram_count(), histogram_sum(), and more). Experimental functions are always enabled in the parser; whether they can be evaluated is decided by the connected Prometheus server. #266
• [FEATURE] PromQL: Support the experimental extended range selectors (anchored and smoothed modifiers) and duration expressions (e.g. foo[5m * 2], step(), min_of()/max_of()) in the parser and tree view. Note that the expression editor does not recognize duration expressions and underlines them as errors; they still parse and execute correctly. #266
• [FEATURE] Autocomplete: Update codemirror-promql to 0.313.0, bringing expression editor support for the Prometheus 3.13 PromQL syntax. #266
• [FEATURE] Native histograms: Display native histogram results in the table view (count, sum, and bucket breakdown) and in the graph view (plotting the histogram sum). #266
• [FEATURE] PromQL: Support the limitk() and limit_ratio() aggregations and the experimental fill()/fill_left()/fill_right() binary operator modifiers in the parser, tree view, editors, and explain views. #266
• [FEATURE] Display warnings and infos returned by the Prometheus query API next to query results and tree nodes. #266
• [ENHANCEMENT] Mark experimental PromQL functions with an "experimental" badge in the function explain view, and add missing short descriptions for the trigonometric functions. #266
• [ENHANCEMENT] Update all Go dependencies to their latest versions and build with Go 1.26. #266
• [ENHANCEMENT] Set datasource ID from URL query parameters. #112
• [ENHANCEMENT] Completely revamp the vector-to-vector binary operation matching visualizer. #124
• [ENHANCEMENT] Add atan2 binary operator support. #117
• [BUGFIX] PromQL: Quote UTF-8 metric and label names when serializing queries (selectors, by/without, on/ignoring, group_left/group_right), and escape control and other non-printable characters in strings like Prometheus does. #266
• [BUGFIX] URL-encode metric and label names in Prometheus API requests, fixing metadata lookups for UTF-8 names. #266

0.3.0 / 2022-12-05

• [SECURITY] Update Exporter Toolkit (CVE-2022-46146) #66
• [BUGFIX] Grafana backend: Overwrite authorization header instead adding another one. #60
• [FEATURE] Sharing: Support Postgres database. #59

0.2.0 / 2022-11-11

• [FEATURE]: Add --version flag and promlens_build_info metric. #54
• [CHANGE]: Remove support for illumos and dragonfly platforms, as well as several specific platform/architecture combinations (see the downloads at https://github.com/prometheus/promlens/releases/tag/v0.2.0 for all available build targets). #50
• [ENHANCEMENT]: Allow building PromLens without CGO by switching to the pure-Go SQLite library glebarez/go-sqlite. This also deprecates the flag value --shared-links.sql.driver=sqlite3 in favor of --shared-links.sql.driver=sqlite. #42
• [ENHANCEMENT]: Allow end-of-file newlines in the Grafana key file by trimming whitespace from the file contents. #43
• [BUGFIX]: Fix PromQL syntax highlighting in the text editor by updating / removing various npm dependencies. #47
• [BUGFIX]: Fix serving of /favicon.ico. #36

0.1.0 / 2022-10-25

This version marks the initial open-sourcing of PromLens to the Prometheus project by PromLabs. See the PromLabs announcement blog post for more details. Note that we are resetting the versioning scheme from the prior proprietary PromLabs version 1.1.0 back to 0.1.0, as this gives us more flexibility with regards to breaking changes. The rationale for allowing a version reset is that the project now lives under a new namespace and governance, including a new location for its source code and Docker images.

• [BREAKING]: All flags related to license keys (--license.key and --license.key-file) have been removed.
• [FEATURE]: All features that previously required a license key are now fully unlocked without a key.
• [FEATURE]: PromLens releases are now published for a wide range of architectures and platforms, both as binary tarballs and as Docker images. See the GitHub releases page and the Docker Hub page for details.
• [FEATURE]: The PromLens web server now supports TLS, authentication, and other web-based settings, using a new --web.config.file flag that works like the equivalent flag in Prometheus.
• [FEATURE]: The PromLens web server now supports listening on multiple addresses by repeating the --web.listen-address flag.
• [FEATURE]: The PromLens web server now supports using a systemd activation listener by using the --web.systemd-socket flag.
• [ENHANCEMENT]: When pressing <Enter> in the expression text editor, the query data for the Graph / Table / Explain tabs in the node visualizer pane are now refreshed even if the expression has not changed.
• [ENHANCEMENT]: Several PromLabs-specific references and pages have been removed from the web UI.
• [ENHANCEMENT]: Various Go- and JavaScript-related dependencies have been updated to their latest versions, which also adds support for the day_of_year() PromQL function.