Add support to pass Datadog API Key as environment variable

[pinxiu]

What is the purpose of the change

Add support to pass Datadog API Key as environment variable to avoid explicitly adding API key in plain text config file.

Brief change log

• Allow passing Datadog API Key as env var

Verifying this change

Please make sure both new and modified tests in this PR follows the conventions defined in our code quality guide: https://flink.apache.org/contributing/code-style-and-quality-common.html#testing

(Please pick either of the following options)

This change is a trivial rework / code cleanup without any test coverage.

(or)

This change is already covered by existing tests, such as (please describe tests).

(or)

This change added tests and can be verified as follows:

(example:)

• Added integration tests for end-to-end deployment with large payloads (100MB)
• Extended integration test for recovery after master (JobManager) failure
• Added test that validates that TaskInfo is transferred only once across recoveries
• Manually verified the change by running a 4 node cluster with 2 JobManagers and 4 TaskManagers, a stateful streaming program, and killing one JobManager and two TaskManagers during the execution, verifying that recovery happens correctly.

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

• Dependencies (does it add or upgrade a dependency): (yes / no)
• The public API, i.e., is any changed class annotated with @Public(Evolving): (yes / no)
• The serializers: (yes / no / don't know)
• The runtime per-record code paths (performance sensitive): (yes / no / don't know)
• Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Kubernetes/Yarn, ZooKeeper: (yes / no / don't know)
• The S3 file system connector: (yes / no / don't know)

Documentation

• Does this pull request introduce a new feature? yes
• If yes, how is the feature documented? (not applicable / docs / JavaDocs / not documented)

[flinkbot]

CI report:

• 90ea579 Azure: SUCCESS

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[UTXOnly]

Hi all,

I'm a support engineer at Datadog and have been working with several customers that requested this feature and would find this very useful as alternative to storing their Datadog API key in plaintext in the config file. Please don't hesitate to reach out if there is anything I can do to help make this feature GA or if you need anymore info from me!

Thanks!

[barryib]

@pinxiu @UTXOnly Any chance to upgrade this PR and resolve conflicts ? Unless you found another way to pass this DD Key securely ?

[swetakala]

Even I need this change, I have opened ticket to address this https://issues.apache.org/jira/browse/FLINK-33994.