@grund/constants

The purpose of this package is to handle and enhance environment variables and expose and interface that provides basic use of commond constants in pretty much any project. It is also use internally by many other @grund packages.

Runtime overrides

Environment variables (or in this case; "constants") can be used in two different situations; application and CLI.

When an application is bundled and shipped we sometimes want to control which variables are overridable and which are not (this of course only applies for NodeJS applications - browser constants are not overridable). This is where the packages @grund/babel-preset and @grund/babel-plugin-inline-env comes in which allows us to do just this.

In a CLI (such as @grund/cli or webpack) we might want either rely on the running environment variables (e.g. NODE_ENV) or we might want to be able to change them for a specific command (e.g. NODE_ENV=production yarn webpack).

To solve for these two cases and still be able to use @grund/constants wherever, the implementation is as follows;

1. If GrundContainer has an instance of the constants key, then we will use this as a single source of the constants. This will be the case in most (if not all?) applications.
2. Otherwise (if constants is not set), we will use process.env as a fallback for all environment values. This is targetted more towards CLI usage. OBS. this also gives the developer the responsibility to make sure that NODE_ENV and RUNTIME_ENV are set.