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Angular Cache

Last week I got a call from our operations team indicating that one of our build server disks was filling up. While investigating what could be the root cause, I noticed the .angular folder for each of our Angular frontend applications.

I had no idea what this folder does, so let us find out together in this blog post…

TLDR; The .angular folder is used by the Angular CLI to cache the previous builds to reduce the build operations and improves the build time.

The .angular folder appeared in version 13 and is used as a disk cache by the Angular CLI to save a number of cachable operations on disk by default. When you re-run the same build, the build system restores the state of the previous build and re-uses previously performed operations, which decreases the time taken to build and test your applications and libraries.

If we look what is inside, we see 2 things:

  • An angular-webpack folder containing the binary files.
  • A babel-webpack folder containing all the text files in .json format.

According to the documentation the disk cache is only enabled for local environments. However you can change this value by  adding the cli.cache object to your Workspace Configuration. The object goes under cli.cache at the top level of the file, outside the projects sections.

The value of environment can be one of the following:

  • all - allows disk cache on all machines.
  • local - allows disk cache only on development machines.
  • ci - allows disk cache only on continuous integration (CI) systems.

So far, so good. The strange this is that although it should only be enabled for local environments, the disk cache seems to be active on our build server as well.

The question is; how does Angular now the difference between our local and CI environment?

I found the answer while browsing through the Angular CLI source code. It checks if an environment variable named CI with a value of ‘true’ is present.

So I logged in on our build server and introduced this environment variable.

More information

Angular - ng cache

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