This release is built with Go 1.15, which deprecates X.509 CommonName
in TLS certificates validation.

In the unlikely case that you use the gRPC API v2 (which is limited to TSDB
admin commands), please note that we will remove this experimental API in the
next minor release 2.22.

[CHANGE] Disable HTTP/2 because of concerns with the Go HTTP/2 client. #7588 #7701
[CHANGE] PromQL: query_log_file path is now relative to the config file. #7701
[CHANGE] Promtool: Replace the tsdb command line tool by a promtool tsdb subcommand. #6088
[CHANGE] Rules: Label rule_group_iterations metric with group name. #7823
[FEATURE] Eureka SD: New service discovery. #3369
[FEATURE] Hetzner SD: New service discovery. #7822
[FEATURE] Kubernetes SD: Support Kubernetes EndpointSlices. #6838
[FEATURE] Scrape: Add per scrape-config targets limit. #7554
[ENHANCEMENT] Support composite durations in PromQL, config and UI, e.g. 1h30m. #7713 #7833
[ENHANCEMENT] DNS SD: Add SRV record target and port meta labels. #7678
[ENHANCEMENT] Docker Swarm SD: Support tasks and service without published ports. #7686
[ENHANCEMENT] PromQL: Reduce the amount of data queried by remote read when a subquery has an offset. #7667
[ENHANCEMENT] Promtool: Add --time option to query instant command. #7829
[ENHANCEMENT] UI: Respect the --web.page-title parameter in the React UI. #7607
[ENHANCEMENT] UI: Add duration, labels, annotations to alerts page in the React UI. #7605
[ENHANCEMENT] UI: Add duration on the React UI rules page, hide annotation and labels if empty. #7606
[BUGFIX] API: Deduplicate series in /api/v1/series. #7862
[BUGFIX] PromQL: Drop metric name in bool comparison between two instant vectors. #7819
[BUGFIX] PromQL: Exit with an error when time parameters can't be parsed. #7505
[BUGFIX] Remote read: Re-add accidentally removed tracing for remote-read requests. #7916
[BUGFIX] Rules: Detect extra fields in rule files. #7767
[BUGFIX] Rules: Disallow overwriting the metric name in the labels section of recording rules. #7787
[BUGFIX] Rules: Keep evaluation timestamp across reloads. #7775
[BUGFIX] Scrape: Do not stop scrapes in progress during reload. #7752
[BUGFIX] TSDB: Fix chunks.HeadReadWriter: maxt of the files are not set error. #7856
[BUGFIX] TSDB: Delete blocks atomically to prevent corruption when there is a panic/crash during deletion. #7772
[BUGFIX] Triton SD: Fix a panic when triton_sd_config is nil. #7671
[BUGFIX] UI: Fix react UI bug with series going on and off. #7804
[BUGFIX] UI: Fix styling bug for target labels with special names in React UI. #7902
[BUGFIX] Web: Stop CMUX and GRPC servers even with stale connections, preventing the server to stop on SIGTERM. #7810

Signed-off-by: Paul Spooren <mail@aparcar.org>