How to enable Debug for integ-test ES server in elastic search

[FreCap]

Running normal tests (without ES RestIntegTestTask) in intellij is very easy. We just import the project and run it it the Debug.

However I cannot find a way to run the underlying ES search server in debug mode.
I tried to add -Dcluster.debug -Dtest.debug, but it doesn't seem opening any port and the test will just run without stopping at breakpoints.

I tried to look at the code of the RestIntegTestTask gradle task (https://github.com/search?q=RestIntegTestTask&type=code), but not much insight from it.

Any advice?

[FreCap]

Is the only way running the tests against a separately deployed ES server?

I tried to:

• build/testclusters/integTest-0/config/jvm.options but it is replaced at every deployement
• add -Dtests.jvm.argline=-agentlib:jdwp=transport=dt_socket,server=y,suspend=y,address=*:5005 (https://github.com/elastic/elasticsearch/blob/7.10/buildSrc/src/main/java/org/elasticsearch/gradle/testclusters/ElasticsearchNode.java#L787) but I couldn't get anything to actually be appended.

@dai-chen do you have any quick hint that could save me?

[FreCap]

For future reference, I found a way to make it work

Adding -Dtests.jvm.argline=-agentlib:jdwp=transport=dt_socket,server=n,address=192.168.4.64:5021,suspend=y to VM options in the intellij Debug configuration

Important, I used server=n because otherwise you need to re-attach the debugger to every ES process (keystore/plugin install, es server etc..). In this way instead you just start the debugger in LISTEN mode and it will automatically re-attach.

[dblock]

This is a good opportunity to extract a TESTING.md document similar to https://github.com/opensearch-project/OpenSearch/blob/main/TESTING.md

[dai-chen]

This PR may fixed the issue. Feel free to reopen if you still face any problem. Thanks!