add multi-arch image(amd64 and s390x) build and publish

[barthy1]

The updates:

• build script was extended to build and publish images with arch
  information in tag (based on TRAVIS_CPU_ARCH env variable value),
  default is amd64
• in build script NEXT_TAG is generated only for amd64, because
  container image to get the value is amd64 only - alpine/semver:5.5.0.
  For s390x this value is stored in Travis workspace (or local file called
  tag.txt)
• git push will work for amd64 only (to avoid push duplicates)
• multi-arch-image script was added to create and push multi-arch
  manifest to dockerhub, joining together separate images for different
  architectures. At this moment amd64 and s390x are added.
• Travis configuration file was extended to have 3 stages:
  • build amd64 images
  • build s390x images
  • generate multi-arch images based on previous stages
• workspace usage was added to Travis config to persist NEXT_TAG data,
  as this value can be received only for amd64 case. s390x is just used it
  after from workspace tag.txt file

Tested for master branch path in Travis

[ozbillwang]

Thanks, @barthy1

This looks really big change !

I don't have other environments (such as s390x), how can I verify your change?

[barthy1]

hey @ozbillwang, thank you for quick response.
Sorry for this large piece of update :(

Which part you would like to verify?
Travis has s390x hardware, and the PR code was tested at least for image build for amd64 and s390x archs.
I also can share my Travis job results with the code for image's build and making multi-arch image.

You can also have a look to my dockerhub with multi-arch image I built using the PR code https://hub.docker.com/repository/docker/barthy/git/tags?page=1
You can pull the image to your amd64 linux machine and corresponding amd64 vesion of the image will be pulled.

[ozbillwang]

can you share your travis build link? Try to access this url https://travis-ci.org/github/barthy1/git, but failed.

[barthy1]

https://travis-ci.com/github/barthy1/git/builds/178733123

[ozbillwang]

Seems its build is similar as normal linux.

Let me think if I can add a test, for example, use the latest build git image for s390, show git versionn and git clone a repo

[barthy1]

It would be great, thank you. Please let me know if I can help.
Or test something on s390x hardware for you.

[barthy1]

hey @ozbillwang any updates or ideas how I can help?
One input from my side, actually in the process of s390x image build there is already the step where s390x image is running and returns git version - https://github.com/alpine-docker/git/pull/23/files#diff-0b83f9dedf40d7356e5ca147a077acb4R33
If you think it makes sense, I can add in my PR the test step in Travis after multi-arch image creation to pull images for both archs, run them and do git clone ?

[barthy1]

hi @ozbillwang just want to check if this PR is still on the table? Please, let me know, if I need to change/update/add something.

[ozbillwang]

@barthy1

Thanks for reminding.

I am not that confidence to support this feature. I pop an idea to add you with write permission as maintainer in this rep, are you fine for this. In the future, any bugs/features about Multi-arch, you can help to support me?

I added you in Linkedin, please accept and share me your mailbox.

update 1

Wait, I doesn't need your mailbox, I can add your account directly in github, let me try

update 2

Invitation has been sent to you.

[barthy1]

@ozbillwang I am ok to support you with multi-arch bugs/features for https://github.com/alpine-docker/git
Invitation is accepted.

[barthy1]

So, do you feel that this PR can be merged?

[ozbillwang]

@barthy1

Yes, let's merge it.

[ozbillwang]

@barthy1

Please review the build jobs, they are fine, but just double check

https://travis-ci.org/github/alpine-docker/git/builds

[barthy1]

I reviewed the build jobs, lgtm.
I also verified s390x and amd64 parts of alpine/git:latest, alpine/git:v2.26.2 and alpine/git:1.0.18. All images are accessible and runnable for both architectures.