Cross compile snap on amd64 to arm

snapcraft
8

I used the following at one point:

architectures:
  - build-on: amd64
  - build-on: i386
  - build-on: armhf

And because the docs say “The default value for run-on is the value of build-on” I thought that should work.

But now I did exactly what you said (but added a build-on value because otherwise snapcraft complains about the yaml schema:

architectures:
  - build-on: all
    run-on: [amd64, i386, armhf]

I didn’t use --target-arch when building.

The result was a example_0.1.0_multi.snap. The “multi” sounded promising, so I transferred the file to an ARM machine, but got:

error: cannot install snap file: snap “example” supported architectures (amd64, i386, armhf) are incompatible with this system (arm64)

My bad, armhf != arm64.

Ok changed the snapcraft.yaml to include arm64. => The file got built successfully! So I transferred it again. This time no error occurred during installation, nice.

But when running:

/snap/example/x1/command-example.wrapper: 2: exec: example: Exec format error

Why? The previous “multi” snap seemed to be built for three architectures and now I additionally included arm64.

Is it because of the go plugin this time? I.e.:

go_archs = {"armhf": "arm", "i386": "386", "ppc64el": "ppc64le"}
env["GOARCH"] = go_archs.get(self.project.deb_arch, self.project.deb_arch)

Ok, one last try for now: With --target-arch…:

$ snapcraft clean example
$ snapcraft build example --target-arch arm64
$ snapcraft --target-arch arm64
...
Snapped example_0.1.0_multi.snap

Why “multi” this time? You said:

in that case the value from --target-arch actually defines the final filename

Well, but maybe it still works on the ARM machine this time…

/snap/example/x1/command-example.wrapper: 2: exec: example: Exec format error

:frowning_face:

Can anyone please provide an example of a “hello world” in Go with a cross compiling snapcraft.yaml and the appropriate snapcraft commands?

Really, I’ve tried so many combinations, none of them are 100% clear from the documentation, and none seem to work. I might be doing something wrong here, but I’m probably not the only one having difficulties, and maybe others trying out snapcraft aren’t as persistent and asking in the forum, but moving to a different solution with a “not production-ready yet” in mind. That’s really bad because I see a lot of potential here and I would love to see this working.

PS:

Not even building ON my ARM machine works:

$ snapcraft
Using 'snap/snapcraft.yaml': Project assets will be searched for from the 'snap' directory.
Support for 'multipass' needs to be set up. Would you like to do that it now? [y/N]: y
snapd is not logged in, snap install commands will use sudo
sudo: unable to resolve host <REDACTED>
multipass (beta) 0.6.1 from Canonical✓ installed
Waiting for multipass...
Launching a VM.
Starting snapcraft-example -[2019-04-29T19:10:01.163] [error] [snapcraft-example] process error occurred FailedToStart
launch failed: failed to start qemu instance
An error occurred with the instance when trying to launch with 'multipass': returned exit code 2.
Ensure that 'multipass' is setup correctly and try again.
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