Re-enable e2e test for ruler

E2E tests for ruler are currently marked as skip. This re-enables the test until it breaks again
and we are able to catch the flakiness.

Also, it removes the test for AlertManager HTTP client pending when we can improve on implementation
(see thanos-io#4056).

Signed-off-by: Michael Okoko <okokomichaels@outlook.com>

test/e2e/rule_test.go

@@ -7,11 +7,9 @@ import (
 	"bytes"
 	"context"
 	"encoding/json"
-	"encoding/pem"
 	"fmt"
 	"io/ioutil"
 	"net/http"
-	"net/http/httptest"
 	"os"
 	"path/filepath"
 	"sync"
@@ -29,7 +27,6 @@ import (
 	"github.com/thanos-io/thanos/pkg/promclient"
 	"github.com/thanos-io/thanos/pkg/query"
 	"github.com/thanos-io/thanos/pkg/rules/rulespb"
-	"github.com/thanos-io/thanos/pkg/runutil"
 	"github.com/thanos-io/thanos/pkg/testutil"
 	"github.com/thanos-io/thanos/test/e2e/e2ethanos"
 )
@@ -223,105 +220,7 @@ func (m *mockAlertmanager) ServeHTTP(resp http.ResponseWriter, req *http.Request
 	m.mtx.Unlock()
 }
 
-// TestRule_AlertmanagerHTTPClient verifies that Thanos Ruler can send alerts to
-// Alertmanager in various setups:
-// * Plain HTTP.
-// * HTTPS with custom CA.
-// * API with a prefix.
-// * API protected by bearer token authentication.
-//
-// Because Alertmanager supports HTTP only and no authentication, the test uses
-// a mocked server instead of the "real" Alertmanager service.
-// The other end-to-end tests exercise against the "real" Alertmanager
-// implementation.
-func TestRule_AlertmanagerHTTPClient(t *testing.T) {
-	t.Skip("TODO: Allow HTTP ports from binaries running on host to be accessible.")
-
-	s, err := e2e.NewScenario("e2e_test_rule_am_http_client")
-	testutil.Ok(t, err)
-	t.Cleanup(e2ethanos.CleanScenario(t, s))
-
-	tlsSubDir := filepath.Join("tls")
-	testutil.Ok(t, os.MkdirAll(filepath.Join(s.SharedDir(), tlsSubDir), os.ModePerm))
-
-	// API v1 with plain HTTP and a prefix.
-	handler1 := newMockAlertmanager("/prefix/api/v1/alerts", "")
-	srv1 := httptest.NewServer(handler1)
-	t.Cleanup(srv1.Close)
-
-	// API v2 with HTTPS and authentication.
-	handler2 := newMockAlertmanager("/api/v2/alerts", "secret")
-	srv2 := httptest.NewTLSServer(handler2)
-	t.Cleanup(srv2.Close)
-
-	var out bytes.Buffer
-	testutil.Ok(t, pem.Encode(&out, &pem.Block{Type: "CERTIFICATE", Bytes: srv2.TLS.Certificates[0].Certificate[0]}))
-	caFile := filepath.Join(s.SharedDir(), tlsSubDir, "ca.crt")
-	testutil.Ok(t, ioutil.WriteFile(caFile, out.Bytes(), 0640))
-
-	rulesSubDir := filepath.Join("rules")
-	testutil.Ok(t, os.MkdirAll(filepath.Join(s.SharedDir(), rulesSubDir), os.ModePerm))
-	createRuleFiles(t, filepath.Join(s.SharedDir(), rulesSubDir))
-
-	r, err := e2ethanos.NewRuler(s.SharedDir(), "1", rulesSubDir, []alert.AlertmanagerConfig{
-		{
-			EndpointsConfig: http_util.EndpointsConfig{
-				StaticAddresses: []string{srv1.Listener.Addr().String()},
-				Scheme:          "http",
-				PathPrefix:      "/prefix/",
-			},
-			Timeout:    model.Duration(time.Second),
-			APIVersion: alert.APIv1,
-		},
-		{
-			HTTPClientConfig: http_util.ClientConfig{
-				TLSConfig: http_util.TLSConfig{
-					CAFile: filepath.Join(e2e.ContainerSharedDir, tlsSubDir, "ca.crt"),
-				},
-				BearerToken: "secret",
-			},
-			EndpointsConfig: http_util.EndpointsConfig{
-				StaticAddresses: []string{srv2.Listener.Addr().String()},
-				Scheme:          "https",
-			},
-			Timeout:    model.Duration(time.Second),
-			APIVersion: alert.APIv2,
-		},
-	}, []query.Config{
-		{
-			EndpointsConfig: http_util.EndpointsConfig{
-				StaticAddresses: func() []string {
-					q, err := e2ethanos.NewQuerier(s.SharedDir(), "1", nil, nil, nil, nil, nil, nil, "", "")
-					testutil.Ok(t, err)
-					return []string{q.NetworkHTTPEndpointFor(s.NetworkName())}
-				}(),
-				Scheme: "http",
-			},
-		},
-	})
-	testutil.Ok(t, err)
-	testutil.Ok(t, s.StartAndWaitReady(r))
-
-	q, err := e2ethanos.NewQuerier(s.SharedDir(), "1", []string{r.GRPCNetworkEndpoint()}, nil, nil, nil, nil, nil, "", "")
-	testutil.Ok(t, err)
-	testutil.Ok(t, s.StartAndWaitReady(q))
-
-	ctx, cancel := context.WithTimeout(context.Background(), 3*time.Minute)
-	t.Cleanup(cancel)
-
-	testutil.Ok(t, runutil.Retry(5*time.Second, ctx.Done(), func() (err error) {
-		for i, am := range []*mockAlertmanager{handler1, handler2} {
-			if len(am.Alerts()) == 0 {
-				return errors.Errorf("no alert received from handler%d, last error: %v", i, am.LastError())
-			}
-		}
-
-		return nil
-	}))
-}
-
 func TestRule(t *testing.T) {
-	t.Skip("Flaky test. Fix it. See: https://github.com/thanos-io/thanos/issues/3425.")
 	t.Parallel()
 
 	s, err := e2e.NewScenario("e2e_test_rule")