Removed Querier duplicate labels checks & made sure store will be not…

… blocked for older Queriers. (#1636)

Changes:
* Cleaned up the code a bit.
* Ensured proper locks.
* thanos_store_nodes_grpc_connections is not per store type and external labels. thanos_store_node_info is marked as deprecated.
* Added (optional, but enabled by default) compatibility label to store GW Info method with flag to disable it. Store only adds it if there is any labelset to advertise.
* Disabled any strict deduplication in external labels detection; just warning!
* More tests; compatibility tests for query pre 0.8.0 and new store GW.
* Remove compatibility label if spotted.

Fixes #1632

Signed-off-by: Bartek Plotka <[email protected]>

CHANGELOG.md

@@ -11,6 +11,13 @@ We use *breaking* word for marking changes that are not backward compatible (rel
 
 ## Unreleased
 
+### Fixed
+
+- [#1632](https://github.com/thanos-io/thanos/issues/1632) Removes the duplicated external labels detection on Thanos Querier; warning only; Made Store Gateway compatible with older Querier versions.
+ NOTE: `thanos_store_nodes_grpc_connections` metric is now per `external_labels` and `store_type`. It is a recommended  metric for Querier storeAPIs. `thanos_store_node_info` is marked as obsolete and will be removed in next release.
+ NOTE2: Store Gateway is not advertising artificial: `"@thanos_compatibility_store_type=store"` label. This is to have current Store Gateway compatible with Querier pre v0.8.0. 
+This label can be disabled by hidden `debug.advertise-compatibility-label=false` flag on Store Gateway.
+
 ## [v0.8.0](https://github.com/thanos-io/thanos/releases/tag/v0.8.0) - 2019.10.10
 
 Lot's of improvements this release! Noteworthy items:
@@ -51,7 +58,7 @@ Selecting blocks to serve depends on the result of block labels relabeling.
 - [#1362](https://github.com/thanos-io/thanos/pull/1362) `query.replica-label` configuration can be provided more than
 once for multiple deduplication labels like: `--query.replica-label=prometheus_replica --query.replica-label=service`.
 - [#1581](https://github.com/thanos-io/thanos/pull/1581) Thanos Store now can use smaller buffer sizes for Bytes pool; reducing memory for some requests.
-- [#1622](https://github.com/thanos-io/thanos/pull/1622) & [#1590](https://github.com/thanos-io/thanos/pull/1590) Updated to Go 1.13.1
+- [#1622](https://github.com/thanos-io/thanos/pull/1622) & [#1590](https://github.com/thanos-io/thanos/pull/1590) Upgraded to Go 1.13.1
 - [#1498](https://github.com/thanos-io/thanos/pull/1498) Thanos Receive change flag `labels` to `label` to be consistent with other commands.
 
 ### Fixed

cmd/thanos/store.go

@@ -60,6 +60,9 @@ func registerStore(m map[string]setupFunc, app *kingpin.Application) {
 	maxTime := model.TimeOrDuration(cmd.Flag("max-time", "End of time range limit to serve. Thanos Store will serve only blocks, which happened eariler than this value. Option can be a constant time in RFC3339 format or time duration relative to current time, such as -1d or 2h45m. Valid duration units are ms, s, m, h, d, w, y.").
 		Default("9999-12-31T23:59:59Z"))
 
+	advertiseCompatibilityLabel := cmd.Flag("debug.advertise-compatibility-label", "If true, Store Gateway in addition to other labels, will advertise special \"@thanos_compatibility_store_type=store\" label set. This makes store Gateway compatible with Querier before 0.8.0").
+		Hidden().Default("true").Bool()
+
 	selectorRelabelConf := regSelectorRelabelFlags(cmd)
 
 	m[component.Store.String()] = func(g *run.Group, logger log.Logger, reg *prometheus.Registry, tracer opentracing.Tracer, debugLogging bool) error {
@@ -92,6 +95,7 @@ func registerStore(m map[string]setupFunc, app *kingpin.Application) {
 				MaxTime: *maxTime,
 			},
 			selectorRelabelConf,
+			*advertiseCompatibilityLabel,
 		)
 	}
 }
@@ -119,6 +123,7 @@ func runStore(
 	blockSyncConcurrency int,
 	filterConf *store.FilterConfig,
 	selectorRelabelConf *extflag.PathOrContent,
+	advertiseCompatibilityLabel bool,
 ) error {
 	statusProber := prober.NewProber(component, logger, prometheus.WrapRegistererWithPrefix("thanos_", reg))
 
@@ -173,6 +178,7 @@ func runStore(
 		blockSyncConcurrency,
 		filterConf,
 		relabelConfig,
+		advertiseCompatibilityLabel,
 	)
 	if err != nil {
 		return errors.Wrap(err, "create object storage store")