问题：
当数据库发生更改时，我如何设置观察程序来实时观察KafkaConnect流？我得到了Error while fetching metadata with correlation id 2 : {dbhistory.Test.Posts=LEADER_NOT_AVAILABLE}。问题的原因是什么？我该如何解决？
上下文：
这个问题与：Debezium如何正确注册带有Kafka Connect的SqlServer连接器-拒绝连接和https://github.com/debezium/debezium-examples/blob/master/tutorial/README.md#using-sql服务器
在Windows10中，我使用以下命令在Zookeeper、Kafka和KafkaConnector各自独立的Docker容器中设置了它们：
docker run -it --rm --name zookeeper -p 2181:2181 -p 2888:2888 -p 3888:3888 debezium/zookeeper:1.1
docker run -it --rm --name kafka -p 9092:9092 -e KAFKA_ADVERTISED_HOST_NAME: kafka --link zookeeper:zookeeper debezium/kafka:1.1
docker run -it --rm --name connect -p 8083:8083 -e GROUP_ID=1 -e CONFIG_STORAGE_TOPIC=my_connect_configs -e OFFSET_STORAGE_TOPIC=my_connect_offsets -e STATUS_STORAGE_TOPIC=my_connect_statuses --link zookeeper:zookeeper --link kafka:kafka debezium/connect:1.1
然后，我将一个Kafka连接器设置到一个在本地主机上运行的SQL Server实例，该实例位于Docker容器之外。日志显示连接器可以连接到数据库并获取CDC数据。到目前为止，我还可以。
但是，当我尝试创建一个观察程序时，使用以下命令：
docker run -it --rm --name watcher --link zookeeper:zookeeper --link kafka:kafka debezium/kafka:1.1
我得到以下错误。
watch-topic -a -k dbhistory.Test.Posts
WARNING: Using default BROKER_ID=1, which is valid only for non-clustered installations.
Using ZOOKEEPER_CONNECT=172.17.0.2:2181
Using KAFKA_ADVERTISED_LISTENERS=PLAINTEXT://172.17.0.5:9092
Using KAFKA_BROKER=172.17.0.3:9092
Contents of topic dbhistory.Test.Posts:
[2020-04-08 15:18:39,373] WARN [Consumer clientId=consumer-console-consumer-3848-1, groupId=console-consumer-3848] Error while fetching metadata with correlation id 2 : {dbhistory.Test.Posts=LEADER_NOT_AVAILABLE} (org.apache.kafka.clients.NetworkClient)
[2020-04-08 16:41:20,501] WARN [Consumer clientId=consumer-console-consumer-3848-1, groupId=console-consumer-3848] Connection to node 1 (/172.17.0.3:9092) could not be established. Broker may not be available. (org.apache.kafka.clients.NetworkClient)
[2020-04-08 16:41:20,605] WARN [Consumer clientId=consumer-console-consumer-3848-1, groupId=console-consumer-3848] Connection to node 1 (/172.17.0.3:9092) could not be established. Broker may not be available. (org.apache.kafka.clients.NetworkClient)
[2020-04-08 16:41:20,807] WARN [Consumer clientId=consumer-console-consumer-3848-1, groupId=console-consumer-3848] Connection to node 1 (/172.17.0.3:9092) could not be established. Broker may not be available. (org.apache.kafka.clients.NetworkClient)
[2020-04-08 16:41:21,262] WARN [Consumer clientId=consumer-console-consumer-3848-1, groupId=console-consumer-3848] Connection to node 1 (/172.17.0.3:9092) could not be established. Broker may not be available. (org.apache.kafka.clients.NetworkClient)
[2020-04-08 16:41:22,120] WARN [Consumer clientId=consumer-console-consumer-3848-1, groupId=console-consumer-3848] Connection to node 1 (/172.17.0.3:9092) could not be established. Broker may not be available. (org.apache.kafka.clients.NetworkClient)
[2020-04-08 16:41:23,330] WARN [Consumer clientId=consumer-console-consumer-3848-1, groupId=console-consumer-3848] Connection to node 1 (/172.17.0.3:9092) could not be established. Broker may not be available. (org.apache.kafka.clients.NetworkClient)
[2020-04-08 16:41:24,189] WARN [Consumer clientId=consumer-console-consumer-3848-1, groupId=console-consumer-3848] Connection to node 1 (/172.17.0.3:9092) could not be established. Broker may not be available. (org.apache.kafka.clients.NetworkClient)
[2020-04-08 16:41:59,826] WARN [Consumer clientId=consumer-console-consumer-3848-1, groupId=console-consumer-3848] Connection to node 1 (/172.17.0.3:9092) could not be established. Broker may not be available. (org.apache.kafka.clients.NetworkClient)
[2020-04-08 16:42:04,051] WARN [Consumer clientId=consumer-console-consumer-3848-1, groupId=console-consumer-3848] Connection to node 1 (/172.17.0.3:9092) could not be established. Broker may not be available. (org.apache.kafka.clients.NetworkClient)
[2020-04-08 16:42:07,121] WARN [Consumer clientId=consumer-console-consumer-3848-1, groupId=console-consumer-3848] Connection to node 1 (/172.17.0.3:9092) could not be established. Broker may not be available. (org.apache.kafka.clients.NetworkClient)
[2020-04-08 16:42:08,024] WARN [Consumer clientId=consumer-console-consumer-3848-1, groupId=console-consumer-3848] Connection to node 1 (/172.17.0.3:9092) could not be established. Broker may not be available. (org.apache.kafka.clients.NetworkClient)
[2020-04-08 16:42:09,354] WARN [Consumer clientId=consumer-console-consumer-3848-1, groupId=console-consumer-3848] Error while fetching metadata with correlation id 11570 : {dbhistory.Test.Posts=LEADER_NOT_AVAILABLE} (org.apache.kafka.clients.NetworkClient)
[2020-04-08 16:42:09,458] WARN [Consumer clientId=consumer-console-consumer-3848-1, groupId=console-consumer-3848] Error while fetching metadata with correlation id 11572 : {dbhistory.Test.Posts=LEADER_NOT_AVAILABLE} (org.apache.kafka.clients.NetworkClient)
[2020-04-08 16:42:09,571] WARN [Consumer clientId=consumer-console-consumer-3848-1, groupId=console-consumer-3848] Error while fetching metadata with correlation id 11574 : {dbhistory.Test.Posts=LEADER_NOT_AVAILABLE} (org.apache.kafka.clients.NetworkClient)
[2020-04-08 16:42:09,677] WARN [Consumer clientId=consumer-console-consumer-3848-1, groupId=console-consumer-3848] Error while fetching metadata with correlation id 11576 : {dbhistory.Test.Posts=LEADER_NOT_AVAILABLE} (org.apache.kafka.clients.NetworkClient)
[2020-04-08 16:42:09,786] WARN [Consumer clientId=consumer-console-consumer-3848-1, groupId=console-consumer-3848] Error while fetching metadata with correlation id 11578 : {dbhistory.Test.Posts=LEADER_NOT_AVAILABLE} (org.apache.kafka.clients.NetworkClient)
[2020-04-08 16:42:09,895] WARN [Consumer clientId=consumer-console-consumer-3848-1, groupId=console-consumer-3848] Error while fetching metadata with correlation id 11580 : {dbhistory.Test.Posts=LEADER_NOT_AVAILABLE} (org.apache.kafka.clients.NetworkClient)
[2020-04-08 16:42:10,002] WARN [Consumer clientId=consumer-console-consumer-3848-1, groupId=console-consumer-3848] Error while fetching metadata with correlation id 11582 : {dbhistory.Test.Posts=LEADER_NOT_AVAILABLE} (org.apache.kafka.clients.NetworkClient)
[2020-04-08 16:42:10,112] WARN [Consumer clientId=consumer-console-consumer-3848-1, groupId=console-consumer-3848] Error while fetching metadata with correlation id 11584 : {dbhistory.Test.Posts=LEADER_NOT_AVAILABLE} (org.apache.kafka.clients.NetworkClient)
[2020-04-08 16:42:10,220] WARN [Consumer clientId=consumer-console-consumer-3848-1, groupId=console-consumer-3848] Error while fetching metadata with correlation id 11586 : {dbhistory.Test.Posts=LEADER_NOT_AVAILABLE} (org.apache.kafka.clients.NetworkClient)
[2020-04-08 16:42:10,326] WARN [Consumer clientId=consumer-console-consumer-3848-1, groupId=console-consumer-3848] Error while fetching metadata with correlation id 11588 : {dbhistory.Test.Posts=LEADER_NOT_AVAILABLE} (org.apache.kafka.clients.NetworkClient)
[2020-04-08 16:42:10,435] WARN [Consumer clientId=consumer-console-consumer-3848-1, groupId=console-consumer-3848] Error while fetching metadata with correlation id 11590 : {dbhistory.Test.Posts=LEADER_NOT_AVAILABLE} (org.apache.kafka.clients.NetworkClient)
[2020-04-08 16:42:10,537] WARN [Consumer clientId=consumer-console-consumer-3848-1, groupId=console-consumer-3848] Error while fetching metadata with correlation id 11592 : {dbhistory.Test.Posts=LEADER_NOT_AVAILABLE} (org.apache.kafka.clients.NetworkClient)
[2020-04-08 16:42:10,648] WARN [Consumer clientId=consumer-console-consumer-3848-1, groupId=console-consumer-3848] Error while fetching metadata with correlation id 11594 : {dbhistory.Test.Posts=LEADER_NOT_AVAILABLE} (org.apache.kafka.clients.NetworkClient)
[2020-04-08 16:42:10,751] WARN [Consumer clientId=consumer-console-consumer-3848-1, groupId=console-consumer-3848] Error while fetching metadata with correlation id 11596 : {dbhistory.Test.Posts=LEADER_NOT_AVAILABLE} (org.apache.kafka.clients.NetworkClient)
[2020-04-08 16:42:10,854] WARN [Consumer clientId=consumer-console-consumer-3848-1, groupId=console-consumer-3848] Error while fetching metadata with correlation id 11598 : {dbhistory.Test.Posts=LEADER_NOT_AVAILABLE} (org.apache.kafka.clients.NetworkClient)
[2020-04-08 17:08:48,268] WARN [Consumer clientId=consumer-console-consumer-3848-1, groupId=console-consumer-3848] Connection to node 1 (/172.17.0.3:9092) could not be established. Broker may not be available. (org.apache.kafka.clients.NetworkClient)
[2020-04-08 17:09:55,602] WARN [Consumer clientId=consumer-console-consumer-3848-1, groupId=console-consumer-3848] Connection to node 1 (/172.17.0.3:9092) could not be established. Broker may not be available. (org.apache.kafka.clients.NetworkClient)
您可以尝试在docker运行中添加--network=host吗。
这个问题很可能是由您定义环境变量的方式引起的。
替换：
-e KAFKA_ADVERTISED_HOST_NAME: kafka
带有：
-e KAFKA_ADVERTISED_HOST_NAME=kafka