Add example listing committed offsets and lag

Author: edenhill

examples/README.md

@@ -1,7 +1,7 @@
 The scripts in this directory provide code examples using Confluent's Python client:
 
 * [adminapi.py](adminapi.py): collection of Kafka Admin API operations
-* [avro-cli.py](avro-cli.py): produces Avro messages with Confluent Schema Registry and then reads them back again 
+* [avro-cli.py](avro-cli.py): produces Avro messages with Confluent Schema Registry and then reads them back again
 * [consumer.py](consumer.py): reads messages from a Kafka topic
 * [producer.py](producer.py): reads lines from stdin and sends them to Kafka
 * [eos-transactions.py](eos-transactions.py): transactional producer with exactly once semantics (EOS)
@@ -12,6 +12,7 @@ The scripts in this directory provide code examples using Confluent's Python cli
 * [protobuf_producer.py](protobuf_producer.py): SerializingProducer with ProtobufSerializer
 * [protobuf_consumer.py](protobuf_consumer.py): DeserializingConsumer with ProtobufDeserializer
 * [sasl_producer.py](sasl_producer.py): SerializingProducer with SASL Authentication
+* [list_offsets.py](list_offsets.py): List committed offsets and consumer lag for group and topics
 
 Additional examples for [Confluent Cloud](https://www.confluent.io/confluent-cloud/):
 

examples/list_offsets.py

@@ -0,0 +1,78 @@
+#!/usr/bin/env python3
+#
+# Copyright 2020 Confluent Inc.
+#
+# 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.
+#
+
+#
+# Show committed offsets and current lag for group and topic(s).
+#
+
+
+import sys
+import confluent_kafka
+
+
+if len(sys.argv) < 4:
+    sys.stderr.write("Usage: {} <brokers> <group.id> <topic> <topic2..>\n".format(sys.argv[0]))
+    sys.exit(1)
+
+brokers, group = sys.argv[1:3]
+
+# Create consumer.
+# This consumer will not join the group, but the group.id is required by
+# committed() to know which group to get offsets for.
+consumer = confluent_kafka.Consumer({'bootstrap.servers': brokers,
+                                     'group.id': group})
+
+
+print("%-50s  %9s  %9s" % ("Topic [Partition]", "Committed", "Lag"))
+print("=" * 72)
+
+for topic in sys.argv[3:]:
+    # Get the topic's partitions
+    metadata = consumer.list_topics(topic, timeout=10)
+    if metadata.topics[topic].error is not None:
+        raise confluent_kafka.KafkaException(metadata.topics[topic].error)
+
+    # Construct TopicPartition list of partitions to query
+    partitions = [confluent_kafka.TopicPartition(topic, p) for p in metadata.topics[topic].partitions]
+
+    # Query committed offsets for this group and the given partitions
+    committed = consumer.committed(partitions, timeout=10)
+
+    for partition in committed:
+        # Get the partitions low and high watermark offsets.
+        (lo, hi) = consumer.get_watermark_offsets(partition, timeout=10, cached=False)
+
+        if partition.offset == confluent_kafka.OFFSET_INVALID:
+            offset = "-"
+        else:
+            offset = "%d" % (partition.offset)
+
+        if hi < 0:
+            lag = "no hwmark"  # Unlikely
+        elif partition.offset < 0:
+            # No committed offset, show total message count as lag.
+            # The actual message count may be lower due to compaction
+            # and record deletions.
+            lag = "%d" % (hi - lo)
+        else:
+            lag = "%d" % (hi - partition.offset)
+
+        print("%-50s  %9s  %9s" % (
+            "{} [{}]".format(partition.topic, partition.partition), offset, lag))
+
+
+consumer.close()