grafana/alloy v1.21.0-rc.0

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Release Candidate 0 for v1.21.0

This is a release candidate and should be used for testing purposes only.

⚠️ This is a pre-release. Do not use in production.

Changes

See the release PR #7234 for the full changelog.

1.21.0 (2026-10-14)

⚠ BREAKING CHANGES

• otelcol.receiver.kafka: otelcol.receiver.kafka and otelcol.exporter.kafka metadata > retry > max_retries now defaults to 20 (was 3) and is now actually applied. Upstream's Kafka client silently ignored it since the franz-go migration. otelcol.exporter.kafka now also applies backoff. (#7366)
• otelcol.connector.signaltometrics: otelcol.connector.signaltometrics error_mode now defaults to ignore (was propagate). A failing OTTL expression now skips the record and logs the error instead of dropping the whole payload. Set error_mode = "propagate" to restore the previous behavior. (#7366)
• loki.write: loki.write configurations that set wal { enabled = true } now fail to load unless Alloy runs with --stability.level=experimental. To keep using the WAL, add --stability.level=experimental to the alloy run command. To keep the default stability level, remove the wal block or set enabled = false. (#7257)
• loki.write: Remove tenant label from metrics (#7232)

Features 🌟

• Add CAP_DAC_OVERRIDE in the allowed Linux capabilities list (#7303) (dddc5d8) (@grcevski)
• database_observability.postgres: Enable stat_statements by default (#7224) (044d3a4) (@matthewnolf)
• database_observability.sql_server: Add health_check collector (#7205) (c1d90e0) (@rgeyer)
• database_observability.sql_server: Add support for clustering mode (#7208) (90100b3) (@matthewnolf)
• database_observability.sql_server: Support monitoring multiple database blocks (#7207) (bbf24e2) (@matthewnolf)
• database_observability: Add engine label for explain_plan log digests (mysql/postgres) (#6944) (551c3ad) (@rgeyer)
• database_observability: Add relabel blocks to database_instance (#7369) (320c17e) (@matthewnolf)
• helm: Add resizePolicy to alloy and config-reloader containers (#7274) (9983d74) (@younsl)
• loki.source.cloudflare: Add api_url argument (#7353) (befe940) (@thampiotr)
• otelcol.connector.signaltometrics: error_mode now defaults to ignore (was propagate) (#7366) (1e353a6) (@ptodev)
• otelcol.encoding.jsonlog: Add the parse_ints argument (#7377) (42fe191) (@ptodev)
• otelcol.exporter.loadbalancing: Add the randomness and attributes routing keys, and the routing_attributes argument (#7377) (42fe191) (@ptodev)
• otelcol.receiver.kafka: metadata > retry > max_retries now defaults to 20 (was 3) (#7366) (1e353a6) (@ptodev)
• otelcol.receiver.kafka: Deprecate metadata > full, which has no effect upstream. This also applies to otelcol.exporter.kafka (#7366) (1e353a6) (@ptodev)
• otelcol.receiver.vcenter: Add the proxy_url argument (#7377) (42fe191) (@ptodev)
• otelcol: Add a partition block (metadata_keys, cache_size, idle_timeout) to the sending_queue > batch block of exporters (#7377) (42fe191) (@ptodev)
• otelcol: Upgrade to OTel Collector v0.162.0 (#7366) (1e353a6) (@ptodev)
• Remove the experimental prometheus.exporter.catchpoint component (#7309) (7b24cb1) (@dehaansa)
• Update Beyla to version 3.38.0 (#7322) (bd8d703) (@grcevski)

Bug Fixes 🐛

• database_observability.postgres: Stop retrying explain plans with missing session settings (#7325) (0bdc41d) (@cristiangreco)
• database_observability.sql_server: Redact native explain-plan XML (#7230) (5b01d2a) (@rgeyer, @cristiangreco)
• database_observability: Correct explain plan cost semantics (#7307) (2cdeba9) (@cristiangreco, @cursoragent)
• database_observability: Escape strings to avoid logfmt parsing issues (#7302) (8b722eb) (@fridgepoet)
• database_observability: Use strconv.Quote on database-derived strings (#7288) (7aad05f) (@cristiangreco)
• deps: Update gosnowflake to v2.2.0 to fix GO-2026-6665 (#7340) (4b1e336) (@thampiotr)
• local.file_match, loki.source.file: Fix matching through Widows junctions (#7261) (653850b) (@ptodev)
• loki.process: Move stage.label validation to syntax.Validator (#7308) (b24cd5d) (@michael-duren)
• loki.process: Move stage.label_keep validation to syntax.Validator (#7244) (1f29bd7) (@michael-duren)
• loki.process: Move stage.limit validation to syntax.Validator (#7278) (9423ed4) (@michael-duren)
• loki.process: Move stage.output validation to syntax.Validator (#7243) (97a5026) (@michael-duren)
• loki.process: Move stage.regex to syntax.Validator (#7342) (0cbb482) (@michael-duren)
• loki.process: Move stage.static_labels validation to syntax.Validator (#7175) (2b92bfb) (@michael-duren)
• loki.process: Move stage.structured_metadata_drop validation to syntax.Validator (#7245) (8b55f30) (@michael-duren)
• loki.process: Move stage.tenant validation to syntax.Validator (#7263) (5f45ab2) (@michael-duren)
• loki.source.docker: Do not time out log streams (#7297) (4b2e798) (@SaiPisey2)
• loki.source.file: Reduce CPU usage for long lines (#7291) (f98aef2) (@kalleep)
• loki.source.kubernetes: Forward log lines with out-of-order timestamps (#7080) (41d9001) (@johnpinto-clarity)
• loki.write: Catch more runtime errors when parsing config (#7216) (32c2180) (@kalleep)
• loki.write: Prevent panic on failed update (#7128) (3aa1c65) (@kalleep)
• loki.write: Remove tenant label from metrics (#7232) (ad6125b) (@kalleep)
• loki.write: Require experimental stability level to enable the WAL (#7257) (cc12943) (@dehaansa)
• loki.write: Retry wal write errors (#7316) (fc8eb73) (@kalleep)
• loki.write: Zero-initialize counters when the metrics registry is reused (#7258) (04838bf) (@dehaansa)
• loki: Add the timestamp to batch size calculation (#7226) (222798c) (@grobinson-grafana)
• loki: Include estimate for stream labels in batch size (#7176) (6c131a1) (@grobinson-grafana)
• loki: Make loki_write_sent_bytes_total and loki_write_dropped_bytes_total count uncompressed bytes (#7228) (4de4474) (@grobinson-grafana)
• otelcol.connector.host_info: Mirror upstream logic and fix potential sources of over-count (#7236) (4371d71) (@jcreixell)
• otelcol.exporter.loki: Release fanout lock when the context ends mid-forward (#7259) (0308c4d) (@dehaansa)
• otelcol.receiver.cloudflare: Default max_request_body_size to 20MiB (#7194) (2eadc7b) (@sindef)
• otelcol.receiver.filelog: Use alphabetical instead of lexicographic sort type (#7212) (d652b74) (@geonusp)
• otelcol.receiver.vcenter: Convert max_query_metrics when converting an OpenTelemetry Collector config (#7377) (42fe191) (@ptodev)
• otelcol: Convert the exporter sending_queue > batch block when converting an OpenTelemetry Collector config (#7377) (42fe191) (@ptodev)
• otelcol: Converters now read the upstream keepalive section of HTTP client and server configs (#7366) (1e353a6) (@ptodev)
• prometheus.remote_write: Tolerate unknown WAL record types on replay (#7189) (26d1a25) (@kgeckhart)

Upgrading

Read the release notes for specific instructions on upgrading from older versions:

Installation

Refer to our installation guide for how to install Grafana Alloy.