Snap maker consistently yields source-type error

[btbaxter]

Preflight Checklist

• I have read the contribution documentation for this project.
• I agree to follow the code of conduct that this project follows, as appropriate.
• I have searched the issue tracker for a bug that matches the one I want to file, without success.

Issue Details

• Electron Forge Version:
  • 6.0.0-beta.50
• Electron Version:
  • 8.0.2
• Operating System:
  • Ubuntu 18.04.4 LTS
• Last Known Working Electron Forge version::
  • N/A

Expected Behavior

Successful make - snap

Actual Behavior

• Without debug: Hangs
• With debug: Errors

To Reproduce

Minimal Test Case

• Initialize new project (yarn create electron-app my-app)
• Add snap maker (yarn add @electron-forge/maker-snap --dev)
• Add debug env (export DEBUG=electron-installer-snap:*)
• Add config for maker-snap (https://www.electronforge.io/config/makers/snapcraft)
• Run make

Minimal Test Case Repo

https://github.com/btbaxter/electron-forge-snap

Additional Information

• Tried on three different machines
• Tried new package from yarn, npx, and electron-forge cli
• Tried make using yarn, npm, and electron-forge
• Tried with base: core18 and without
• Tried config in package.json and forge.config.js
• Tried with different features included/excluded
• Tried other beta versions of electron-forge
• Tried maker on complex and minimal apps

Similar to #1439 - had to independently install multipass. Also have to delete/purge any project multipass instances between attempts.

Everything yields the same base error -- Failed to pull source: unable to determine source type of '/home/btbaxter/my-app/out'. Check that the URL is correct or consider specifying `source-type` for this part. See `snapcraft help sources` for more information.

• out directory contains make/snap/x64 (empty) & my-app-linux-x64 with packaged app

I know it's more likely that I'm making a fundamental mistake here, but I've read all the docs I can find, tried multiple configs, and am at a loss.

yarn run v1.22.0
$ electron-forge make
✔ Checking your system
✔ Resolving Forge Config
We need to package your application before we can make it
✔ Preparing to Package Application for arch: x64
✔ Preparing native dependencies
✔ Packaging Application
Making for the following targets: snap
⠋ Making for target: snap - On platform: linux - For arch: x64  electron-installer-snap:default_args Reading package metadata from /home/btbaxter/my-app/out/my-app-linux-x64/resources/app/package.json +0ms
  electron-installer-snap:yaml Loading YAML template /home/btbaxter/my-app/node_modules/electron-installer-snap/resources/snapcraft.yaml +0ms
⠙ Making for target: snap - On platform: linux - For arch: x64  electron-installer-snap:yaml Adding MPRIS feature +56ms
  electron-installer-snap:yaml Replacing browser-support plug with browser-sandbox +0ms
The browser-sandbox feature will trigger a manual review in the Snap store.
  electron-installer-snap:yaml Writing new YAML file /tmp/electron-snap-14202SkCOngA3xBvJ/snap/snapcraft.yaml +3ms
  electron-installer-snap:snapcraft Running '/snap/bin/snapcraft snap --target-arch=amd64 --output=/home/btbaxter/my-app/out/make/snap/x64/my-app_1.0.0_amd64.snap' in /tmp/electron-snap-14202SkCOngA3xBvJ +0ms
⠦ Making for target: snap - On platform: linux - For arch: x64Setting target machine to 'amd64'
Launching a VM.
⠸ Making for target: snap - On platform: linux - For arch: x64Failed to pull source: unable to determine source type of '/home/btbaxter/my-app/out'.
Check that the URL is correct or consider specifying `source-type` for this part. See `snapcraft help sources` for more information.
⠙ Making for target: snap - On platform: linux - For arch: x64Run the same command again with --debug to shell into the environment if you wish to introspect this failure.
✖ Making for target: snap - On platform: linux - For arch: x64

An unhandled error has occurred inside Forge:
An error occured while making for target: snap
Command failed with a non-zero return code (2):
/snap/bin/snapcraft snap --target-arch=amd64 --output=/home/btbaxter/my-app/out/make/snap/x64/my-app_1.0.0_amd64.snap
Error: Command failed with a non-zero return code (2):
/snap/bin/snapcraft snap --target-arch=amd64 --output=/home/btbaxter/my-app/out/make/snap/x64/my-app_1.0.0_amd64.snap
    at ChildProcess.<anonymous> (/home/btbaxter/my-app/node_modules/@malept/cross-spawn-promise/src/index.ts:114:16)
    at ChildProcess.emit (events.js:321:20)
    at ChildProcess.EventEmitter.emit (domain.js:485:12)
    at maybeClose (internal/child_process.js:1026:16)
    at Process.ChildProcess._handle.onexit (internal/child_process.js:286:5)
error Command failed with exit code 1.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.

[malept]

I can't reproduce this on either Travis CI or GitHub Actions:

https://travis-ci.org/malept/electron-forge-demo123/jobs/657649048
https://github.com/malept/electron-forge-demo123/runs/481764099?check_suite_focus=true

Although I had a look at your package.json and it's odd that @electron-forge/maker-snap is in dependencies instead of devDependencies.

[btbaxter]

tl;dr - My fault. Snapcraft was setup incorrectly.

Thanks for your help with this. Just having access to that Travis CI instance gave me a starting point for troubleshooting. I worked backwards, getting my own minimal demo running through Travis CI before moving back to my local machine.

The root of the problem was my unfamiliarity with snap & snapcraft. I installed snapcraft using the instructions on snapcraft.io. Those instructions tell you to install snapcraft through snap. And, based on a multipass error, I had a global instance of multipass installed (through snap) on a couple of the test machines. After purging both of those installs entirely from snap and simply installing snapcraft (and dependencies) through apt, things cleared up.

(And the @electron-forge/maker-snap dependency/dev-dependency mistake was just from rushing to deploy the minimal demo. I thought I had fixed the issue prior to publishing. Sorry.)