PLM-207: Add operation timeout parameter (#136)

Author: balthazar

README.md

@@ -163,6 +163,12 @@ bin/plm \
     --log-json
 ```
 
+## Environment Variables
+
+- `PLM_SOURCE_URI`: MongoDB connection string for the source cluster.
+- `PLM_TARGET_URI`: MongoDB connection string for the target cluster.
+- `PLM_MONGODB_CLI_OPERATION_TIMEOUT`: Timeout for MongoDB client operations; accepts Go durations like `30s`, `2m`, `1h` (default: `5m`).
+
 ## Log JSON Fields
 
 When using the `--log-json` option, the logs will be output in JSON format with the following fields:

config/const.go

@@ -44,9 +44,10 @@ const (
 	DisconnectTimeout = 5 * time.Second
 	// CloseCursorTimeout is the timeout duration for closing cursor.
 	CloseCursorTimeout = 10 * time.Second
-	// OperationTimeout is the timeout duration for MonngoDB client operations like
-	// insert, update, delete, etc.
-	OperationTimeout = 5 * time.Minute
+	// DefaultMongoDBCliOperationTimeout is the default timeout duration for MongoDB client
+	// operations like insert, update, delete, etc. It can be overridden via
+	// environment variable (see config.OperationMongoDBCliTimeout()).
+	DefaultMongoDBCliOperationTimeout = 5 * time.Minute
 )
 
 // Change stream and replication settings.

config/values.go

@@ -6,6 +6,7 @@ import (
 	"slices"
 	"strconv"
 	"strings"
+	"time"
 
 	"github.com/dustin/go-humanize"
 )
@@ -82,3 +83,17 @@ func UseTargetClientCompressors() []string {
 
 	return rv
 }
+
+// OperationMongoDBCliTimeout returns the effective timeout for MongoDB client operations.
+// If the environment variable `PLM_MONGODB_CLI_OPERATION_TIMEOUT` is set, it must be a valid
+// time duration string (e.g., "30s", "2m", "1h"). Otherwise, the
+// DefaultMongoDBCliOperationTimeout is used.
+func OperationMongoDBCliTimeout() time.Duration {
+	if v := strings.TrimSpace(os.Getenv("PLM_MONGODB_CLI_OPERATION_TIMEOUT")); v != "" {
+		if d, err := time.ParseDuration(v); err == nil && d > 0 {
+			return d
+		}
+	}
+
+	return DefaultMongoDBCliOperationTimeout
+}

topo/connect.go

@@ -58,7 +58,7 @@ func ConnectWithOptions(
 		SetReadPreference(readpref.Primary()).
 		SetReadConcern(readconcern.Majority()).
 		SetWriteConcern(writeconcern.Majority()).
-		SetTimeout(config.OperationTimeout)
+		SetTimeout(config.OperationMongoDBCliTimeout())
 
 	if connOpts != nil && connOpts.Compressors != nil {
 		opts.SetCompressors(connOpts.Compressors)