Add tenant resolver (#3486)

* Add tenant resolver package

This implements the multi tenant resolver as described by the [proposal]
for multi tenant query-federation.

By default it behaves like before, but it's implementation can be
swapped out.

[proposal]: cortexproject/cortex#3364

Signed-off-by: Christian Simon <simon@swine.de>

* Replace usages of `ExtractOrgID`

Use TenantID or UserID depending on which of the methods are meant to be
used.

Signed-off-by: Christian Simon <simon@swine.de>

* Replace usages of `ExtractOrgIDFromHTTPRequest`

This is replaced by ExtractTenantIDFromHTTPRequest, which makes sure
that exactly one tenant ID is set.

Signed-off-by: Christian Simon <simon@swine.de>

* Add methods to `tenant` package to use resolver directly

Signed-off-by: Christian Simon <simon@swine.de>

* Remove UserID method from Resolver interface

We need a better definition for what we are trying to achieve with
UserID before we can add it to the interface

Signed-off-by: Christian Simon <simon@swine.de>

* Update comment on the TenantID/TenantIDs

Signed-off-by: Christian Simon <simon@swine.de>

* Improve performance of NormalizeTenantIDs

- reduce allocations by reusing the input slice during de-duplication

Signed-off-by: Christian Simon <simon@swine.de>

pkg/distributor/distributor.go

@@ -26,6 +26,7 @@ import (
 	"github.com/cortexproject/cortex/pkg/prom1/storage/metric"
 	"github.com/cortexproject/cortex/pkg/ring"
 	ring_client "github.com/cortexproject/cortex/pkg/ring/client"
+	"github.com/cortexproject/cortex/pkg/tenant"
 	"github.com/cortexproject/cortex/pkg/util"
 	"github.com/cortexproject/cortex/pkg/util/extract"
 	"github.com/cortexproject/cortex/pkg/util/limiter"
@@ -384,7 +385,7 @@ func (d *Distributor) validateSeries(ts ingester_client.PreallocTimeseries, user
 
 // Push implements client.IngesterServer
 func (d *Distributor) Push(ctx context.Context, req *client.WriteRequest) (*client.WriteResponse, error) {
-	userID, err := user.ExtractOrgID(ctx)
+	userID, err := tenant.TenantID(ctx)
 	if err != nil {
 		return nil, err
 	}

pkg/distributor/distributor_test.go

@@ -32,6 +32,7 @@ import (
 	ring_client "github.com/cortexproject/cortex/pkg/ring/client"
 	"github.com/cortexproject/cortex/pkg/ring/kv"
 	"github.com/cortexproject/cortex/pkg/ring/kv/consul"
+	"github.com/cortexproject/cortex/pkg/tenant"
 	"github.com/cortexproject/cortex/pkg/util"
 	"github.com/cortexproject/cortex/pkg/util/chunkcompat"
 	"github.com/cortexproject/cortex/pkg/util/flagext"
@@ -426,7 +427,7 @@ func TestDistributor_PushHAInstances(t *testing.T) {
 					d.HATracker = r
 				}
 
-				userID, err := user.ExtractOrgID(ctx)
+				userID, err := tenant.TenantID(ctx)
 				assert.NoError(t, err)
 				err = d.HATracker.checkReplica(ctx, userID, tc.cluster, tc.acceptedReplica)
 				assert.NoError(t, err)
@@ -1322,7 +1323,7 @@ func (i *mockIngester) Push(ctx context.Context, req *client.WriteRequest, opts
 		i.metadata = map[uint32]map[client.MetricMetadata]struct{}{}
 	}
 
-	orgid, err := user.ExtractOrgID(ctx)
+	orgid, err := tenant.TenantID(ctx)
 	if err != nil {
 		return nil, err
 	}

pkg/distributor/query.go

@@ -9,11 +9,11 @@ import (
 	"github.com/prometheus/common/model"
 	"github.com/prometheus/prometheus/pkg/labels"
 	"github.com/weaveworks/common/instrument"
-	"github.com/weaveworks/common/user"
 
 	"github.com/cortexproject/cortex/pkg/ingester/client"
 	ingester_client "github.com/cortexproject/cortex/pkg/ingester/client"
 	"github.com/cortexproject/cortex/pkg/ring"
+	"github.com/cortexproject/cortex/pkg/tenant"
 	"github.com/cortexproject/cortex/pkg/util"
 	"github.com/cortexproject/cortex/pkg/util/extract"
 	grpc_util "github.com/cortexproject/cortex/pkg/util/grpc"
@@ -76,7 +76,7 @@ func (d *Distributor) QueryStream(ctx context.Context, from, to model.Time, matc
 // GetIngestersForQuery returns a replication set including all ingesters that should be queried
 // to fetch series matching input label matchers.
 func (d *Distributor) GetIngestersForQuery(ctx context.Context, matchers ...*labels.Matcher) (ring.ReplicationSet, error) {
-	userID, err := user.ExtractOrgID(ctx)
+	userID, err := tenant.TenantID(ctx)
 	if err != nil {
 		return ring.ReplicationSet{}, err
 	}
@@ -107,7 +107,7 @@ func (d *Distributor) GetIngestersForQuery(ctx context.Context, matchers ...*lab
 // GetIngestersForMetadata returns a replication set including all ingesters that should be queried
 // to fetch metadata (eg. label names/values or series).
 func (d *Distributor) GetIngestersForMetadata(ctx context.Context) (ring.ReplicationSet, error) {
-	userID, err := user.ExtractOrgID(ctx)
+	userID, err := tenant.TenantID(ctx)
 	if err != nil {
 		return ring.ReplicationSet{}, err
 	}