Use the $usage variables in the [env] section for dynamic environments

[brentmitchell25]

It would be nice to use the $usage variables when trying to set environment variables or file references. This would allow a user to have multiple dotenv files like .env.local, .env.dev, .env.staging, etc. This would allow the user or ci to only run: mise deploy <env>.

Here are a few examples:

[tasks."deploy"]
env.'_'.file = { path = ".env.$usage_environment" }
usage = '''
arg "<environment>" "Environment name"
'''
run = """
pnpm deploy
"""

Since there is an option to wait until the tools are initialized, it might make sense to do this:
env.'_'.file = { path = ".env.$usage_environment", tools = true }
Or maybe add another similar option for usage?
env.'_'.file = { path = ".env.$usage_environment", usage = true }

[risu729]

I think you can use the MISE_ENV_FILE environment variable.
like:

[tasks."deploy"]
usage = '''
arg "<environment>" "Environment name"
'''
run = """
MISE_ENV_FILE=.env.$usage_environment pnpm deploy
"""

[briankchan]

I'd actually like this for a different reason: sometimes, we may want to use an argument to set an environment variable directly, and there isn't a shell-independent way to do this.

For example, I want to pass an env var named TAG to docker buildx bake. The bake command doesn't allow setting env vars from the CLI arguments, so we need to set it from the shell command. With sh, it's pretty easy to set env vars inline:

[tasks.build]
usage = '''
option "--tag <tag>"
'''
run = "TAG=$usage_tag docker buildx bake"

but this wouldn't work on Windows. I assume it would be possible to use a separate run_windows command using syntax for cmd, but it would be nice if mise could handle this, e.g.:

[tasks.build]
usage = '''
option "--tag <tag>"
'''
env.TAG = { value = '{{ env.usage_tag }}', usage = true }
run = "docker buildx bake"

(This syntax would be rather verbose, but it's better than nothing. I assume that this feature cannot be default behavior because the usage args can be set by env vars, but it would be even nicer if we could just write env.TAG = '{{ env.usage_tag }}')

[stryan]

+1 to this; I have a lot of scripts that rely on environmental variables for configuration that I'd like to wrap in mise tasks but setting them all on the run command line like FOO=BAR sh script.sh gets very unwieldy very quickly.