config: support env var expansion in relabel_configs#18457
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Mentigen wants to merge 4 commits intoprometheus:mainfrom
Open
config: support env var expansion in relabel_configs#18457Mentigen wants to merge 4 commits intoprometheus:mainfrom
Mentigen wants to merge 4 commits intoprometheus:mainfrom
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I believe this should be opt-in. |
Add support for expanding environment variables in Replacement and TargetLabel
fields of relabel_configs, metric_relabel_configs, and alert_relabel_configs.
This allows users to reference environment variables like $JOB_NAME or ${CUSTOM_LABEL}
in relabel configurations, enabling dynamic configuration based on deployment environment.
Preserves regex capture group references ($1, $2, etc.) which are not treated as
environment variables. Expansion happens after YAML parsing and before configuration
validation to ensure all values are properly expanded.
Fixes prometheus#12563
Signed-off-by: Ilya Kiselev <[email protected]>
Address reviewer feedback: expansion of environment variables in relabel_configs is now opt-in, disabled by default. Enable with --enable-feature=expand-relabel-env-vars. Without the flag, behaviour is unchanged: $VAR references in replacement and target_label are treated as literals (or regex capture groups). With the flag, they are expanded via os.Expand before the config is applied, matching the existing behaviour of global.external_labels. Changes: - config.Load and config.LoadFile accept a new expandRelabelEnv bool - cmd/prometheus: parse the new feature flag; thread it through reloadConfig into LoadFile - cmd/promtool: pass false (no expansion in config-check / sd-check) - docs/feature_flags.md: document the new flag Signed-off-by: Ilya Kiselev <[email protected]>
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Add missing bool parameter (expandRelabelEnv=false) to config.Load calls in scrape/manager_test.go and scrape/scrape_test.go. Signed-off-by: Ilya Kiselev <[email protected]>
- Combine adjacent bool params in reloadConfig signature to satisfy gocritic paramTypeCombine rule - Regenerate docs/command-line/prometheus.md to include the new expand-relabel-env-vars feature flag (required by TestDocumentation) Signed-off-by: Ilya Kiselev <[email protected]>
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Which issue(s) does the PR fix:
Fixes #12563
Release notes for end users (ALL commits must be considered).
Reviewers should verify clarity and quality.
Summary
Add support for expanding environment variables in
ReplacementandTargetLabelfields ofrelabel_configs,metric_relabel_configs, andalert_relabel_configs, similar to the existing support inglobal.external_labels.Changes
expandEnvVars()helper function for consistent env var expansionexpandRelabelConfigs()helper to expand Replacement and TargetLabel fieldscontainsEnvVar()to distinguish env var refs from regex capture group refs ($1, $2)TestExpandRelabelConfigswith test fixtureUsers can now use environment variables in relabel configs:
Test plan
go test ./config/...TestExpandRelabelConfigspasses with env var expansion