007-Hash_and_Lock.md

title	nav_order
Hash and Lock	8

Hash and Lock

Each time the assets for a package are processed, a lock file named .composer_compiled_assets is saved in the root directory of the package.

That file should be git-ignored if the compiled assets are git-ignored.

The lock file contains a hash, referenced as "Composer Asset Compiler package's hash", which is created based on Composer Assets Compiler configuration and the contents of certain files such as package.json, package-lock.json, npm-shrinkwrap.json, and yarn.lock.

If a lock file is found, and its content matches the hash calculated for the current package, the package will not be processed.

That is especially important when Composer Assets Compiler auto-executes on Composer install, otherwise Composer Assets Compiler would process assets for all packages, even if none changed.

Custom source files

Very likely, the compiled assets will change when the assets "sources" are changed. Composer Assets Compiler is not aware of where sources are located, so it can't take those into account when calculating the hash.

That's why there's a src-paths configuration, that can be used to instruct Composer Assets Compiler about the source files to use as a base for the package's hash.

{
  "name": "acme/some-theme",
  "extra": {
    "composer-asset-compiler": {
      "script": "build",
      "src-paths": [
        "./js/*.js",
        "./sass/*.scss"
      ]
    }
  }
}

Please note Composer Asset Compiler uses Symfony Finder component behind the scenes, which means the wildcard to indicate "one or more folders" is *, not **.

What affect hash generation

• The content of package.json, package-lock.json, npm-shrinkwrap.json, and yarn.lock files (if exising)
• The content of any file found in the paths in the src-paths config (if any)
• The "evaluated" script, which might depend on: environment variables, default-env configuration, and execution mode.
• The "dependencies" configuration.

Ignoring lock

When compiling assets via the compile-assets command, it is possible to pass a --ignore-lock flag to always build assets, regardless the presence and the content of the lock file.

composer compile-assets --ignore-lock=*

Calculate package's hash on demand

The hash of the package can also be calculated programmatically using the command:

composer assets-hash

That can be useful to generate the filename of the archive during pre-compilation, in case we want to use the ${hash} placeholder.

The command accept a --mode flag because mode might affect the calculated hash.