Added query-frontend integration test

[pracucci]

What this PR does:
Today @pstibrany was working on #2088 and while testing it in a dev cluster we realized the read path wasn't working despite all unit tests and integration tests passed. The issue was caused by the query-frontend --> querier worker which is currently not tested by integration tests. This PR adds such test.

To prove this test would have spotted the issue in #2088:

$ hub pr checkout 2088
$ git merge --squash add-query-frontend-integration-test

# Manually edit modules.go to remove the quick fix

$ git diff
diff --git a/pkg/cortex/modules.go b/pkg/cortex/modules.go
index 81c715036..e1aa7c695 100644
--- a/pkg/cortex/modules.go
+++ b/pkg/cortex/modules.go
@@ -260,7 +260,7 @@ func (t *Cortex) initQuerier(cfg *Config) (err error) {
        api.Register(promRouter)

        subrouter := t.server.HTTP.PathPrefix("/api/prom").Subrouter()
-       subrouter.PathPrefix("/api/v1").Handler(fakeRemoteAddr(t.httpAuthMiddleware.Wrap(promRouter)))
+       subrouter.PathPrefix("/api/v1").Handler(t.httpAuthMiddleware.Wrap(promRouter))
        subrouter.Path("/read").Handler(t.httpAuthMiddleware.Wrap(querier.RemoteReadHandler(queryable)))
        subrouter.Path("/validate_expr").Handler(t.httpAuthMiddleware.Wrap(http.HandlerFunc(t.distributor.ValidateExprHandler)))
        subrouter.Path("/chunks").Handler(t.httpAuthMiddleware.Wrap(querier.ChunksHandler(queryable)))

$ make ./cmd/cortex/.uptodate
$ go test -timeout 30s github.com/cortexproject/cortex/integration -run ^(TestQueryFrontendWithChunksStorage)$ -v -count=1

=== RUN   TestQueryFrontendWithChunksStorage
Starting consul
consul: ==> Starting Consul agent...
consul: ==> Consul agent running!
consul: Version: 'v0.9.4'
consul: Node ID: '554902f8-bd7c-d7f1-81c5-be8d2db844e3'
consul: Node name: 'consul'
consul: Datacenter: 'dc1' (Segment: '<all>')
consul: Server: true (Bootstrap: false)
consul: Client Addr: 0.0.0.0 (HTTP: 8500, HTTPS: -1, DNS: 8600)
consul: Cluster Addr: 127.0.0.1 (LAN: 8301, WAN: 8302)
consul: Encrypt: Gossip: false, TLS-Outgoing: false, TLS-Incoming: false
consul: ==> Log data will now stream in as it occurs:
Ports for container: e2e-cortex-test-consul Mapping: map[8500:32856]
Starting dynamodb
Ports for container: e2e-cortex-test-dynamodb Mapping: map[8000:32857]
dynamodb: Initializing DynamoDB Local with the following configuration:
dynamodb: Port:	8000
dynamodb: InMemory:	true
dynamodb: DbPath:	null
dynamodb: SharedDb:	true
dynamodb: shouldDelayTransientStatuses:	false
dynamodb: CorsParams:	*
Starting table-manager
Ports for container: e2e-cortex-test-table-manager Mapping: map[80:32858]
Starting query-frontend
query-frontend: level=info ts=2020-02-18T16:29:31.690960512Z caller=cortex.go:252 msg=initialising module=runtime-config
query-frontend: level=info ts=2020-02-18T16:29:31.691092144Z caller=manager.go:68 msg="runtime config disabled: file not specified"
query-frontend: level=info ts=2020-02-18T16:29:31.691116819Z caller=cortex.go:252 msg=initialising module=server
query-frontend: level=info ts=2020-02-18T16:29:31.692799198Z caller=server.go:147 http=[::]:80 grpc=[::]:9095 msg="server listening on addresses"
query-frontend: level=info ts=2020-02-18T16:29:31.693291284Z caller=cortex.go:252 msg=initialising module=overrides
query-frontend: level=info ts=2020-02-18T16:29:31.693384803Z caller=cortex.go:252 msg=initialising module=query-frontend
query-frontend: level=info ts=2020-02-18T16:29:31.69341854Z caller=main.go:100 msg="Starting Cortex" version="(version=, branch=, revision=)"
Ports for container: e2e-cortex-test-query-frontend Mapping: map[80:32860 9095:32859]
Starting distributor
Ports for container: e2e-cortex-test-distributor Mapping: map[80:32861]
Starting querier
consul: ==> Newer Consul version available: 1.7.0 (currently running: 0.9.4)
Ports for container: e2e-cortex-test-querier Mapping: map[80:32862]
Starting ingester
querier: level=info ts=2020-02-18T16:29:33.868435298Z caller=cortex.go:252 msg=initialising module=memberlist-kv
querier: level=info ts=2020-02-18T16:29:33.868492877Z caller=cortex.go:252 msg=initialising module=server
querier: level=info ts=2020-02-18T16:29:33.868776323Z caller=server.go:147 http=[::]:80 grpc=[::]:9095 msg="server listening on addresses"
querier: level=info ts=2020-02-18T16:29:33.868900406Z caller=cortex.go:252 msg=initialising module=runtime-config
querier: level=info ts=2020-02-18T16:29:33.86892777Z caller=manager.go:68 msg="runtime config disabled: file not specified"
querier: level=info ts=2020-02-18T16:29:33.868940132Z caller=cortex.go:252 msg=initialising module=overrides
querier: level=info ts=2020-02-18T16:29:33.868950255Z caller=cortex.go:252 msg=initialising module=store
querier: level=info ts=2020-02-18T16:29:33.903905675Z caller=cortex.go:252 msg=initialising module=ring
querier: level=info ts=2020-02-18T16:29:33.904204857Z caller=cortex.go:252 msg=initialising module=distributor
querier: level=info ts=2020-02-18T16:29:33.908408591Z caller=cortex.go:252 msg=initialising module=querier-chunk-store
querier: level=info ts=2020-02-18T16:29:33.908513176Z caller=cortex.go:252 msg=initialising module=querier
querier: level=info ts=2020-02-18T16:29:33.910261023Z caller=main.go:100 msg="Starting Cortex" version="(version=, branch=, revision=)"
querier: level=info ts=2020-02-18T16:29:33.939840017Z caller=client.go:212 msg="value is nil" key=collectors/ring index=1
Ports for container: e2e-cortex-test-ingester Mapping: map[80:32863]
Killing ingester
ingester: level=warn ts=2020-02-18T16:29:35.142926281Z caller=transfer.go:422 msg="transfer attempt failed" err="cannot find ingester to transfer chunks to: no pending ingesters" attempt=1 max_retries=10
Killing querier
querier: level=info ts=2020-02-18T16:29:35.699513087Z caller=signals.go:55 msg="=== received SIGINT/SIGTERM ===\n*** exiting"
querier: level=info ts=2020-02-18T16:29:35.700223812Z caller=cortex.go:278 msg=stopping module=querier
querier: level=error ts=2020-02-18T16:29:35.700294643Z caller=worker.go:123 msg="error from DNS watcher" err="watcher has been closed"
querier: level=error ts=2020-02-18T16:29:35.700322256Z caller=worker.go:177 msg="error processing requests" err="rpc error: code = Canceled desc = context canceled"
querier: level=info ts=2020-02-18T16:29:35.700364803Z caller=cortex.go:278 msg=stopping module=querier-chunk-store
querier: level=info ts=2020-02-18T16:29:35.700377297Z caller=cortex.go:278 msg=stopping module=store
querier: level=info ts=2020-02-18T16:29:35.700402641Z caller=cortex.go:278 msg=stopping module=distributor
querier: level=info ts=2020-02-18T16:29:35.700422988Z caller=cortex.go:278 msg=stopping module=overrides
querier: level=info ts=2020-02-18T16:29:35.700505124Z caller=cortex.go:278 msg=stopping module=ring
querier: level=info ts=2020-02-18T16:29:35.700514359Z caller=cortex.go:278 msg=stopping module=memberlist-kv
querier: level=info ts=2020-02-18T16:29:35.700524004Z caller=cortex.go:278 msg=stopping module=runtime-config
querier: level=info ts=2020-02-18T16:29:35.700532689Z caller=cortex.go:278 msg=stopping module=server
Killing distributor
Killing query-frontend
query-frontend: level=info ts=2020-02-18T16:29:36.726489135Z caller=signals.go:55 msg="=== received SIGINT/SIGTERM ===\n*** exiting"
query-frontend: level=info ts=2020-02-18T16:29:36.726605981Z caller=cortex.go:278 msg=stopping module=query-frontend
query-frontend: level=info ts=2020-02-18T16:29:36.726633893Z caller=cortex.go:278 msg=stopping module=overrides
query-frontend: level=info ts=2020-02-18T16:29:36.726649405Z caller=cortex.go:278 msg=stopping module=runtime-config
query-frontend: level=info ts=2020-02-18T16:29:36.726665066Z caller=cortex.go:278 msg=stopping module=server
Killing table-manager
Killing dynamodb
Killing consul
--- FAIL: TestQueryFrontendWithChunksStorage (17.24s)
    /workspace/src/github.com/cortexproject/cortex/integration/query_frontend_test.go:75: 
        	Error Trace:	query_frontend_test.go:75
        	            				query_frontend_test.go:24
        	Error:      	Received unexpected error:
        	            	execution: missing port in address
        	Test:       	TestQueryFrontendWithChunksStorage
FAIL
FAIL	github.com/cortexproject/cortex/integration	17.361s
FAIL
Error: Tests failed.

Which issue(s) this PR fixes:
N/A

Checklist

• Tests updated
• Documentation added
• CHANGELOG.md updated - the order of entries should be [CHANGE], [FEATURE], [ENHANCEMENT], [BUGFIX]

[pstibrany]

Thanks for adding this Marco!

[jtlisi]

LGTM