REP-5328 Compare shard keys as part of metadata verification.

.github/workflows/all.yml

@@ -41,8 +41,14 @@ jobs:
             srcConnStr: mongodb://localhost:27020,localhost:27021,localhost:27022
             dstConnStr: mongodb://localhost:27030,localhost:27031,localhost:27032
 
+          - name: replset-to-sharded
+            dstArgs: --sharded 2
+            srcConnStr: mongodb://localhost:27020,localhost:27021,localhost:27022
+            dstConnStr: mongodb://localhost:27030
+
           - name: sharded
-            args: --sharded 2
+            srcArgs: --sharded 2
+            dstArgs: --sharded 2
             srcConnStr: mongodb://localhost:27020
             dstConnStr: mongodb://localhost:27030
 
@@ -82,8 +88,8 @@ jobs:
       - name: Start clusters
         run: |-
             {
-                echo mlaunch init --binarypath $(cat .srcpath) --port 27020 --dir src --replicaset ${{ matrix.topology.args }}
-                echo mlaunch init --binarypath $(cat .dstpath) --port 27030 --dir dst --replicaset ${{ matrix.topology.args }}
+                echo mlaunch init --binarypath $(cat .srcpath) --port 27020 --dir src --replicaset ${{ matrix.topology.srcArgs }}
+                echo mlaunch init --binarypath $(cat .dstpath) --port 27030 --dir dst --replicaset ${{ matrix.topology.dstArgs }}
                 echo mlaunch init --binarypath $(cat .metapath) --port 27040 --dir meta --replicaset --nodes 1
             } | parallel
 

internal/util/askserver.go

@@ -0,0 +1,66 @@
+package util
+
+import (
+	"context"
+	"slices"
+
+	"github.com/10gen/migration-verifier/mslices"
+	"github.com/10gen/migration-verifier/option"
+	"github.com/pkg/errors"
+	"go.mongodb.org/mongo-driver/bson"
+	"go.mongodb.org/mongo-driver/mongo"
+)
+
+// ServerThinksTheseMatch runs an aggregation on the server that determines
+// whether the server thinks a & b are equal. This allows you, e.g., to
+// ignore BSON type differences for equivalent numbers.
+//
+// tinker is an optional pipeline that operates on the documents in the
+// pipeline (`a` and `b`, respectively) before they're compared.
+//
+// In migration-verifier the client is generally expected to be for
+// the metadata cluster.
+func ServerThinksTheseMatch(
+	ctx context.Context,
+	client *mongo.Client,
+	a, b any,
+	tinker option.Option[mongo.Pipeline],
+) (bool, error) {
+	pipeline := mongo.Pipeline{
+		{{"$documents", []bson.D{
+			{
+				{"a", bson.D{{"$literal", a}}},
+				{"b", bson.D{{"$literal", b}}},
+			},
+		}}},
+
+		// Now check to be sure that those specs match.
+		{{"$match", bson.D{
+			{"$expr", bson.D{
+				{"$eq", mslices.Of("$a", "$b")},
+			}},
+		}}},
+	}
+
+	if extra, hasExtra := tinker.Get(); hasExtra {
+		pipeline = slices.Insert(
+			pipeline,
+			1,
+			extra...,
+		)
+	}
+
+	cursor, err := client.Database("admin").Aggregate(ctx, pipeline)
+
+	if err == nil {
+		defer cursor.Close(ctx)
+
+		if cursor.Next(ctx) {
+			return true, nil
+		}
+
+		err = cursor.Err()
+	}
+
+	return false, errors.Wrapf(err, "failed to ask server if a (%v) matches b (%v)", a, b)
+}

internal/util/sharding.go

@@ -0,0 +1,54 @@
+package util
+
+import (
+	"context"
+
+	"github.com/10gen/migration-verifier/option"
+	"github.com/pkg/errors"
+	"go.mongodb.org/mongo-driver/bson"
+	"go.mongodb.org/mongo-driver/mongo"
+)
+
+const (
+	configDBName  = "config"
+	collsCollName = "collections"
+)
+
+// GetShardKey returns the collection's shard key, or an empty option
+// if the collection is unsharded.
+func GetShardKey(
+	ctx context.Context,
+	coll *mongo.Collection,
+) (option.Option[bson.Raw], error) {
+	namespace := coll.Database().Name() + "." + coll.Name()
+
+	configCollectionsColl := coll.Database().Client().
+		Database(configDBName).
+		Collection(collsCollName)
+
+	decoded := struct {
+		Key option.Option[bson.Raw]
+	}{}
+
+	err := configCollectionsColl.
+		FindOne(ctx, bson.D{{"_id", namespace}}).
+		Decode(&decoded)
+
+	if errors.Is(err, mongo.ErrNoDocuments) {
+		return option.None[bson.Raw](), nil
+	} else if err != nil {
+		return option.None[bson.Raw](), errors.Wrapf(
+			err,
+			"failed to find sharding info for %#q",
+			namespace,
+		)
+	}
+
+	key, hasKey := decoded.Key.Get()
+
+	if !hasKey {
+		return option.None[bson.Raw](), nil
+	}
+
+	return option.Some(key), nil
+}

internal/verifier/check.go

@@ -20,7 +20,7 @@ const (
 	GenerationComplete           GenerationStatus = "complete"
 )
 
-var failedStatus = mapset.NewSet(
+var failedStatuses = mapset.NewSet(
 	verificationTaskFailed,
 	verificationTaskMetadataMismatch,
 )
@@ -406,7 +406,7 @@ func FetchFailedAndIncompleteTasks(ctx context.Context, coll *mongo.Collection,
 		return FailedTasks, IncompleteTasks, err
 	}
 	for _, t := range allTasks {
-		if failedStatus.Contains(t.Status) {
+		if failedStatuses.Contains(t.Status) {
 			FailedTasks = append(FailedTasks, t)
 		} else if t.Status != verificationTaskCompleted {
 			IncompleteTasks = append(IncompleteTasks, t)

internal/verifier/integration_test_suite.go

@@ -5,9 +5,9 @@ import (
 	"strings"
 	"time"
 
+	"github.com/10gen/migration-verifier/internal/util"
 	mapset "github.com/deckarep/golang-set/v2"
 	"github.com/pkg/errors"
-	"github.com/samber/lo"
 	"github.com/stretchr/testify/suite"
 	"go.mongodb.org/mongo-driver/bson"
 	"go.mongodb.org/mongo-driver/mongo"
@@ -16,13 +16,8 @@ import (
 	"go.mongodb.org/mongo-driver/mongo/writeconcern"
 )
 
-type TestTopology string
-
 const (
-	metaDBName                   = "VERIFIER_TEST_META"
-	topologyEnvVar               = "MVTEST_TOPOLOGY"
-	TopologyReplset TestTopology = "replset"
-	TopologySharded TestTopology = "sharded"
+	metaDBName = "VERIFIER_TEST_META"
 )
 
 type IntegrationTestSuite struct {
@@ -139,22 +134,14 @@ func (suite *IntegrationTestSuite) TearDownTest() {
 	}
 }
 
-func (suite *IntegrationTestSuite) GetSrcTopology() TestTopology {
-	hello := struct {
-		Msg string
-	}{}
-
-	resp := suite.srcMongoClient.Database("admin").RunCommand(
+func (suite *IntegrationTestSuite) GetTopology(client *mongo.Client) util.ClusterTopology {
+	clusterInfo, err := util.GetClusterInfo(
 		suite.Context(),
-		bson.D{{"hello", 1}},
-	)
-
-	suite.Require().NoError(
-		resp.Decode(&hello),
-		"should fetch & decode hello",
+		client,
 	)
+	suite.Require().NoError(err, "should fetch src cluster info")
 
-	return lo.Ternary(hello.Msg == "isdbgrid", TopologySharded, "")
+	return clusterInfo.Topology
 }
 
 func (suite *IntegrationTestSuite) BuildVerifier() *Verifier {

internal/verifier/metadata.go

@@ -0,0 +1,93 @@
+package verifier
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+
+	"github.com/10gen/migration-verifier/internal/util"
+	"github.com/10gen/migration-verifier/option"
+	"github.com/pkg/errors"
+	"github.com/samber/lo"
+	"go.mongodb.org/mongo-driver/mongo"
+)
+
+// This is the Field for a VerificationResult for shard key mismatches.
+const ShardKeyField = "Shard Key"
+
+func (verifier *Verifier) verifyShardingIfNeeded(
+	ctx context.Context,
+	srcColl, dstColl *mongo.Collection,
+) ([]VerificationResult, error) {
+
+	// We only need to compare if both clusters are sharded
+	srcSharded := verifier.srcClusterInfo.Topology == util.TopologySharded
+	dstSharded := verifier.dstClusterInfo.Topology == util.TopologySharded
+
+	if !srcSharded || !dstSharded {
+		return nil, nil
+	}
+
+	srcShardOpt, err := util.GetShardKey(ctx, srcColl)
+	if err != nil {
+		return nil, errors.Wrapf(
+			err,
+			"failed to fetch %#q's shard key on source",
+			FullName(srcColl),
+		)
+	}
+
+	dstShardOpt, err := util.GetShardKey(ctx, dstColl)
+	if err != nil {
+		return nil, errors.Wrapf(
+			err,
+			"failed to fetch %#q's shard key on destination",
+			FullName(dstColl),
+		)
+	}
+
+	srcKey, srcIsSharded := srcShardOpt.Get()
+	dstKey, dstIsSharded := dstShardOpt.Get()
+
+	if !srcIsSharded && !dstIsSharded {
+		return nil, nil
+	}
+
+	if srcIsSharded != dstIsSharded {
+		return []VerificationResult{{
+			Field:     ShardKeyField,
+			Cluster:   lo.Ternary(srcIsSharded, ClusterTarget, ClusterSource),
+			Details:   Missing,
+			NameSpace: FullName(srcColl),
+		}}, nil
+	}
+
+	if bytes.Equal(srcKey, dstKey) {
+		return nil, nil
+	}
+
+	areEqual, err := util.ServerThinksTheseMatch(
+		ctx,
+		verifier.metaClient,
+		srcKey, dstKey,
+		option.None[mongo.Pipeline](),
+	)
+	if err != nil {
+		return nil, errors.Wrapf(
+			err,
+			"failed to ask server if shard keys (src %v; dst: %v) match",
+			srcKey,
+			dstKey,
+		)
+	}
+
+	if !areEqual {
+		return []VerificationResult{{
+			Field:     ShardKeyField,
+			Details:   fmt.Sprintf("%s: src=%v; dst=%v", Mismatch, srcKey, dstKey),
+			NameSpace: FullName(srcColl),
+		}}, nil
+	}
+
+	return nil, nil
+}