Reuse angular cache in CI

[Dassderdie]

Angular CLI saves a number of cachable operations on disk. This cache should be reused by our ci.
Our cache is located under frontend/.angular/cache.

[ClFeSc]

How can we detect whether the Cache needs to be invalidated (i.e. when is it outdated)? Does Angular detect that on its own?

[Dassderdie]

As far as I understood it angular reuses some parts of the cache and updates the invalid ones automatically. So we would probably have to update the cached angular cache after each run.

[Dassderdie]

There are several parts of the pipeline that are cached on disk, the main benefit of this is that future compilations become warm as the build state is restored from disk instead of having to start the build from a cold state. This helps to decrease the build time by up to 65% as a number of computations are not performed.

There are a number of things that are cached, including but not limited to:

• Babel transformations
• Results of the minified CSS and JS
• Build dependencies and resolutions
• Modules transformation result

The cache is expected to continue to grow unless it is periodically purged by the users. The more code changes are performed in a repo, the larger the cache will become. You can read the cache documentation on how to clear the cache.

In future, we are hoping to perform automatic cleanups of stalled cache data.

angular/angular-cli#22323 (comment)