Spago bundle-app requires config in 0.15 version

[Nimor111]

Hello,

After upgrading the version of spago in my project to 0.15.2 where I use the bundle-app command it started failing with the following error:

[error] Failed to read the config. Error was:
[error] There's no "spago.dhall" in your current location.

This does not happen in version 0.14.0.

Poking around the code a bit, I found that in version 0.15 the command has the following line:
https://github.com/purescript/spago/blob/0.15.2/app/Spago.hs#L89

Which has a call to Run.withBuildEnv which as far as I can trace the code boils down to this:
https://github.com/purescript/spago/blob/0.15.2/src/Spago/RunEnv.hs#L72

Which requires a spago.dhall to be present.

While in 0.14.0, it seems to not require a spago.dhall:
https://github.com/purescript/spago/blob/0.14.0/app/Spago.hs#L441

Is this intentional?

Some more details about my setup:
I am using spago2nix and running the command with the following flags:
spago bundle-app --no-install --no-build --main Main --to dist/app.js

Thanks in advance!

[f-f]

Thanks for reporting this and for noting the details about your setup - it seems like you found a "nice" corner case.

The answer to your question is that this was "sort of intentional": this breakage happened in #610 where we restructured the "runtime environments" to clarify their requirements (e.g. "needs purs", "needs git", "needs a valid config")

You can see here that bundle-app is invoked in a BuildEnv:

spago/app/Spago.hs

Lines 90 to 91 in 8c44f1c

	BundleApp modName tPath shouldBuild buildOptions -> Run.withBuildEnv globalUsePsa
	$ Spago.Build.bundleApp WithMain modName tPath shouldBuild buildOptions

Which makes sense because if we need to install&build we need that. Except if we pass --no-build (as you did), which skips all of that and just bundles - see line 255:

spago/src/Spago/Build.hs

Lines 250 to 255 in 8c44f1c

	bundleApp withMain maybeModuleName maybeTargetPath noBuild buildOpts =
	let (moduleName, targetPath) = prepareBundleDefaults maybeModuleName maybeTargetPath
	bundleAction = Purs.bundle withMain (withSourceMap buildOpts) moduleName targetPath
	in case noBuild of
	DoBuild -> build buildOpts (Just bundleAction)
	NoBuild -> bundleAction

So, this is a bug and we should take note of how the no-build flag affects the requirements of the code