Add cmd option to change default architecture

[computeralex92]

I added a command line option to colima to change the used architecture.

Why?

Sometimes I have the need to run on a M1 a docker container which is only for Intel based environments build.
A ARM-based colima environment have some issues with it:

$ docker run --platform linux/amd64 alpine:latest uname -a
Unable to find image 'alpine:latest' locally
latest: Pulling from library/alpine
a0d0a0d46f8b: Pull complete
Digest: sha256:e1c082e3d3c45cccac829840a25941e679c25d438cc8412c2fa221cf1a824e6a
Status: Downloaded newer image for alpine:latest
standard_init_linux.go:228: exec user process caused: exec format error

After change

$ ./_output/colima-amd64 start -a x86_64
INFO[0000] starting colima
INFO[0000] creating and starting ...                     context=vm
INFO[0321] provisioning ...                              context=docker
INFO[0321] provisioning in VM ...                        context=docker
INFO[0484] restarting VM to complete setup ...           context=docker
INFO[0485] stopping ...                                  context=vm
INFO[0508] starting ...                                  context=vm
INFO[0622] starting ...                                  context=docker
INFO[0663] done
$ docker run --platform linux/amd64 alpine:latest uname -a
Unable to find image 'alpine:latest' locally
latest: Pulling from library/alpine
a0d0a0d46f8b: Pull complete
Digest: sha256:e1c082e3d3c45cccac829840a25941e679c25d438cc8412c2fa221cf1a824e6a
Status: Downloaded newer image for alpine:latest
Linux d2bdff871931 5.13.0-19-generic #19-Ubuntu SMP Thu Oct 7 21:58:00 UTC 2021 x86_64 Linux

Trade Off

The disk speed of the VM is quite bad compared to the native ARM environment; but I didn't speed test it yet.

[abiosoft]

Thanks for this.

Are you using Colima on an M1 device?

[computeralex92]

Thanks for this.

Are you using Colima on an M1 device?

Yes, I'm using it on a M1.

[abiosoft]

Yes, I'm using it on a M1.

Good to hear 🎉 . Now I can update the readme accordingly.

[abiosoft]

@computeralex92 Hi, if you would not mind helping with testing, multiple instances support has been added with the --profile flag.

Rather than deleting and recreating for arm and x86 docker images, you can now simply have multiple instances and shut down the ones you're not using.

The following will create a colima instance with profile name x86 independent of your other instance(s).

colima start --profile x86 --arch aarch64

This is currently on the main branch and I am looking to make it part of the next release.

[abiosoft]

This should not require creating multiple instances anymore. A solution is in the works.

[abiosoft]

FYI, this now works out of the box and no additional steps is required.