add --experimental-max-learner flag

Signed-off-by: Sam Batschelet <sbatsche@redhat.com>

server/etcdserver/bootstrap_test.go

@@ -0,0 +1,140 @@
+// Copyright 2021 The etcd Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package version implements etcd version parsing and contains latest version
+// information.
+
+package etcdserver
+
+import (
+	"encoding/json"
+	"io"
+	"net/http"
+	"strings"
+	"testing"
+
+	"go.etcd.io/etcd/api/v3/etcdserverpb"
+	"go.etcd.io/etcd/api/v3/version"
+	"go.etcd.io/etcd/client/pkg/v3/types"
+	"go.etcd.io/etcd/server/v3/config"
+	"go.etcd.io/etcd/server/v3/etcdserver/api/membership"
+	"go.uber.org/zap"
+)
+
+func TestBootstrapExistingClusterNoWALMaxLearner(t *testing.T) {
+	tests := []struct {
+		name          string
+		members       []etcdserverpb.Member
+		maxLearner    int
+		hasError      bool
+		expectedError error
+	}{
+		{
+			name: "bootstrap success: maxLearner gt learner count",
+			members: []etcdserverpb.Member{
+				{ID: 4512484362714696085, PeerURLs: []string{"http://localhost:2380"}},
+				{ID: 5321713336100798248, PeerURLs: []string{"http://localhost:2381"}},
+				{ID: 5670219998796287055, PeerURLs: []string{"http://localhost:2382"}},
+			},
+			maxLearner:    1,
+			hasError:      false,
+			expectedError: nil,
+		},
+		{
+			name: "bootstrap success: maxLearner eq learner count",
+			members: []etcdserverpb.Member{
+				{ID: 4512484362714696085, PeerURLs: []string{"http://localhost:2380"}, IsLearner: true},
+				{ID: 5321713336100798248, PeerURLs: []string{"http://localhost:2381"}},
+				{ID: 5670219998796287055, PeerURLs: []string{"http://localhost:2382"}, IsLearner: true},
+			},
+			maxLearner:    2,
+			hasError:      false,
+			expectedError: nil,
+		},
+		{
+			name: "bootstrap fail: maxLearner lt learner count",
+			members: []etcdserverpb.Member{
+				{ID: 4512484362714696085, PeerURLs: []string{"http://localhost:2380"}},
+				{ID: 5321713336100798248, PeerURLs: []string{"http://localhost:2381"}, IsLearner: true},
+				{ID: 5670219998796287055, PeerURLs: []string{"http://localhost:2382"}, IsLearner: true},
+			},
+			maxLearner:    1,
+			hasError:      true,
+			expectedError: membership.ErrTooManyLearners,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			cluster, err := types.NewURLsMap("node0=http://localhost:2380,node1=http://localhost:2381,node2=http://localhost:2382")
+			if err != nil {
+				t.Fatalf("unexpected error: %v", err)
+			}
+			cfg := config.ServerConfig{
+				Name:                    "node0",
+				InitialPeerURLsMap:      cluster,
+				Logger:                  zap.NewExample(),
+				ExperimentalMaxLearners: tt.maxLearner,
+			}
+			_, err = bootstrapExistingClusterNoWAL(cfg, mockBootstrapRoundTrip(tt.members))
+			hasError := err != nil
+			if hasError != tt.hasError {
+				t.Errorf("expected error: %v got: %v", tt.hasError, err)
+			}
+			if hasError && !strings.Contains(err.Error(), tt.expectedError.Error()) {
+				t.Fatalf("expected error to contain: %q, got: %q", tt.expectedError.Error(), err.Error())
+			}
+		})
+	}
+}
+
+type roundTripFunc func(r *http.Request) (*http.Response, error)
+
+func (s roundTripFunc) RoundTrip(r *http.Request) (*http.Response, error) {
+	return s(r)
+}
+
+func mockBootstrapRoundTrip(members []etcdserverpb.Member) roundTripFunc {
+	return func(r *http.Request) (*http.Response, error) {
+		switch {
+		case strings.Contains(r.URL.String(), "/members"):
+			return &http.Response{
+				StatusCode: http.StatusOK,
+				Body:       io.NopCloser(strings.NewReader(mockMembersJSON(members))),
+				Header:     http.Header{"X-Etcd-Cluster-Id": []string{"f4588138892a16b0"}},
+			}, nil
+		case strings.Contains(r.URL.String(), "/version"):
+			return &http.Response{
+				StatusCode: http.StatusOK,
+				Body:       io.NopCloser(strings.NewReader(mockVersionJSON())),
+			}, nil
+		case strings.Contains(r.URL.String(), DowngradeEnabledPath):
+			return &http.Response{
+				StatusCode: http.StatusOK,
+				Body:       io.NopCloser(strings.NewReader(`true`)),
+			}, nil
+		}
+		return nil, nil
+	}
+}
+
+func mockVersionJSON() string {
+	v := version.Versions{Server: "3.7.0", Cluster: "3.7.0"}
+	version, _ := json.Marshal(v)
+	return string(version)
+}
+
+func mockMembersJSON(m []etcdserverpb.Member) string {
+	members, _ := json.Marshal(m)
+	return string(members)
+}