[FLINK-15442] Harden the Avro Confluent Schema Registry nightly end-to-end test

[KarmaGYZ]

What is the purpose of the change

Harden the Avro Confluent Schema Registry nightly end-to-end test.

Brief change log

• Wrap the error when execute cleanup command in retry_times_with_backoff_and_cleanup function.
• Harden the way to loop in retry_times_with_backoff_and_cleanup

Verifying this change

Trigger the Avro Confluent Schema Registry nightly end-to-end test.

Does this pull request potentially affect one of the following parts:

• Dependencies (does it add or upgrade a dependency): no
• The public API, i.e., is any changed class annotated with @Public(Evolving): no
• The serializers: no
• The runtime per-record code paths (performance sensitive): no
• Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Yarn/Mesos, ZooKeeper: no
• The S3 file system connector: no

Documentation

• Does this pull request introduce a new feature? no
• If yes, how is the feature documented? no

[flinkbot]

Thanks a lot for your contribution to the Apache Flink project. I'm the @flinkbot. I help the community
to review your pull request. We will use this comment to track the progress of the review.

Automated Checks

Last check on commit b542834 (Thu Jan 02 06:04:49 UTC 2020)

Warnings:

• No documentation files were touched! Remember to keep the Flink docs up to date!

_{Mention the bot in a comment to re-run the automated checks.}

Review Progress

• ❓ 1. The [description] looks good.
• ❓ 2. There is [consensus] that the contribution should go into to Flink.
• ❓ 3. Needs [attention] from.
• ❓ 4. The change fits into the overall [architecture].
• ❓ 5. Overall code [quality] is good.

Please see the Pull Request Review Guide for a full explanation of the review process.

The Bot is tracking the review progress through labels. Labels are applied according to the order of the review items. For consensus, approval by a Flink committer of PMC member is required

Bot commands

The @flinkbot bot supports the following commands:

• @flinkbot approve description to approve one or more aspects (aspects: description, consensus, architecture and quality)
• @flinkbot approve all to approve all aspects
• @flinkbot approve-until architecture to approve everything until architecture
• @flinkbot attention @username1 [@username2 ..] to require somebody's attention
• @flinkbot disapprove architecture to remove an approval you gave earlier

[flinkbot]

CI report:

• b542834 Travis: SUCCESS Azure: SUCCESS
• 623ff81 Travis: SUCCESS Azure: SUCCESS
• 3318d11 Travis: SUCCESS Azure: SUCCESS
• bae0233 Travis: CANCELED Azure: PENDING

Bot commands

The @flinkbot bot supports the following commands:

• @flinkbot run travis re-run the last Travis build
• @flinkbot run azure re-run the last Azure build

[KarmaGYZ]

cc @tillrohrmann
Travis gives green light to the relevant test.
https://travis-ci.org/KarmaGYZ/flink/builds/632126284

[tillrohrmann]

Thanks for opening this PR @KarmaGYZ. I left some comments as I don't fully understand why the changes are hardening the test script. At the moment, I thought that the downloading KAFKA_URL would be retried. Hence, I fear that your changes might not really have an effect.

[tillrohrmann]

Why is this better than the previous for loop version?

[KarmaGYZ]

This block of loop will only executes 1 time in this scenario. I found that there is also a for loop in start_confluent_schema_registry function:

for i in {1..30}; do
    if get_and_verify_schema_subjects_exist; then
        echo "Schema registry is up."
        return 0
    fi
    echo "Waiting for schema registry..."
    sleep 1
  done

The variable i is set to 30 after this function, which cause the loop end after only 1 execute.

[tillrohrmann]

I tried to reproduce the problem via

for i in {1..30}; do
  echo $i
done

for (( i = 0; i < 10; i++ )) do
  echo $i
done

When I execute this, then 1..30 and 0..9 will be printed. Hence, I'm not sure I really understand the problem you are describing. Could you provide me an example script to reproduce the problem with the old for loop?

[KarmaGYZ]

I think current scenario equals to the following script:

for (( i = 0; i < 10; i++ )) do
  for i in {1..30}; do
     echo $i
  done
  echo $i
done

[tillrohrmann]

Ah this makes sense. Thanks a lot for your explanation.

[KarmaGYZ]

Thanks for the review @tillrohrmann . I've updated the PR.

Travis link https://travis-ci.org/KarmaGYZ/flink/builds/633584290

[tillrohrmann]

Thanks for looking into my comments @KarmaGYZ. I fear I still don't understand the problem with the loops. I tried to reproduce what you've described but I wasn't able to do so. Could you provide me with a minimal example to reproduce the described problem?

[tillrohrmann]

I tried to reproduce the problem via

for i in {1..30}; do
  echo $i
done

for (( i = 0; i < 10; i++ )) do
  echo $i
done

When I execute this, then 1..30 and 0..9 will be printed. Hence, I'm not sure I really understand the problem you are describing. Could you provide me an example script to reproduce the problem with the old for loop?

[KarmaGYZ]

Thanks for the review @tillrohrmann . I've removed the retry-delay and explained what happened in the loop.

[tillrohrmann]

Thanks a lot for the hardening and the explanation why it works @KarmaGYZ. LGTM. Merging this PR now.

[tillrohrmann]

Ah this makes sense. Thanks a lot for your explanation.