How can I tell which port Apache Flink runs on?

Question

I installed apache flink, went to the flink-1.14.3 folder and ran .bin/start-cluster.sh.

It appears to have started the cluster successfully because it output this-

Starting cluster.
Starting standalonesession daemon on host MacBook.local.
Starting taskexecutor daemon on host MacBook.local.

How can I tell which port Flink is running on? I went to http://localhost:8081/ in my browser, but there's nothing there.

Perhaps you have something else already bound to port 8081, in which case Flink won't be able to grab that port. — David Anderson, Jan 21 '22 at 10:09
I made the mistake of installing the wrong version of Java. I had 17.x instead of 11.x — Cauder, Jan 22 '22 at 17:08

score 2 · Accepted Answer · answered Jan 21 '22 at 06:03

2

Per https://nightlies.apache.org/flink/flink-docs-release-1.14/docs/try-flink/local_installation/ you should be able to access it on http://localhost:8081/

answered Jan 21 '22 at 06:03

Martijn Visser

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score 0 · Answer 2 · answered Jan 25 '22 at 09:36

The port of the WebUI is specified in conf/flink-conf.yaml with the option rest.port. As the official documentation says, the default value of the port is 8081. If the port has already been used by other applications, you could specify another one in conf/flink-conf.yaml.

If you wish to find which application is listening to 8081, you could refer to these answers:

Who is listening on a given TCP port on Mac OS X? https://unix.stackexchange.com/questions/106561/finding-the-pid-of-the-process-using-a-specific-port

If there's no applications using the port 8081 and you cannot access the WebUI via localhost:8081, maybe it's because Flink itself is not running normally. For the local installation of Flink, you could check log files located at the log folder and find out what happened.

How can I tell which port Apache Flink runs on?

2 Answers2

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