[hotfix] [docs] Fix broken flink-training links in hands-on section

[kylerballiet]

What is the purpose of the change

Fix broken flink-training links in the Learn Flink docs. Several pages have a "Hands-on" section that use the training_repo and training_link shortcodes (e.g. Intro to the DataStream API, Data Pipelines & ETL, Streaming Analytics, Event-driven Applications). Two issues affected all of these: (1) the repo link pointed to a branch (e.g. release-2.2) that does not exist in apache/flink-training; (2) the exercise links used blob for paths that are directories in the repo, so the URLs were wrong. Both shortcodes are now updated to fallback to master branch if TrainingBranch is not specified in docs/config.toml, and the exercise shortcode uses tree instead of blob, so the links work on every page that uses them.

Brief change log

• training_repo.html: fallback to master branch for the repo if .Site.Params.TrainingBranch is not able to be resolved
• training_link.html: use tree instead of blob for exercise paths, fallback to master branch

Verifying this change

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

I built the docs locally using the project's pinned Hugo version (0.124.1 via setup_hugo.sh and build_docs.sh) and verified the flink-training and exercise links on all affected Learn Flink pages (DataStream API, Data Pipelines & ETL, Streaming Analytics, Event-driven Applications); the links resolve correctly on each page. Note: building with a newer Hugo (e.g. 0.157 from Homebrew) produced several unrelated template errors, so I used the pinned version for verification.

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

• Dependencies: no
• The public API: no
• The serializers: no
• The runtime per-record code paths: no
• Anything that affects deployment or recovery: no
• The S3 file system connector: no

Documentation

• Does this pull request introduce a new feature? no
• If yes, how is the feature documented? not applicable

[flinkbot]

CI report:

• ba3eeb9 Azure: SUCCESS

Bot commands

The @flinkbot bot supports the following commands:

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

[featzhang]

Thanks for fixing the broken links 👍

Since the original implementation used .Site.Params.Branch, it might be better to keep the parameterization instead of hardcoding master.

For example:

{{ .Site.Params.TrainingBranch | default "master" }}

This would allow the training repository branch to be configurable in the future.

[rionmonster]

I was able to pull down the proposed fixes from the branch and verify that the links look good on this end:

docs-verification.mov

Looks good to me!