Make the pack build warn that the positional argument will not be treated as the source directory path

[hhiroshell]

Summary

This PR makes the pack build warn that the positional argument specifying the image name will not be treated as the source directory path, addressing #2231.

Output

Before

$ pack build sample-app --builder cnbs/sample-builder:jammy
jammy: Pulling from cnbs/sample-builder
Digest: sha256:9db376e26252b6cbc75190c88ea24571da36ec0d373136be233b32fd174962fc
Status: Image is up to date for cnbs/sample-builder:jammy
...

After

pack build warns it if both of the following criteria are met:

• The build artifact is not specified as an OCI file layout.
• The --path flag is not used.

$ pack build sample-app --builder cnbs/sample-builder:jammy
Warning: You are building an image named 'sample-app'. If you mean it as an app directory path, run 'pack build <args> --path sample-app'
jammy: Pulling from cnbs/sample-builder
Digest: sha256:9db376e26252b6cbc75190c88ea24571da36ec0d373136be233b32fd174962fc
Status: Image is up to date for cnbs/sample-builder:jammy
...

pack build doesn't warn it if the build artifact is specified as an OCI file layout.

$ pack config experimental true
Experimental features enabled!

$ pack build oci:sample-app --builder cnbs/sample-builder:jammy
jammy: Pulling from cnbs/sample-builder
Digest: sha256:9db376e26252b6cbc75190c88ea24571da36ec0d373136be233b32fd174962fc
Status: Image is up to date for cnbs/sample-builder:jammy
...

pack build doesn't warn it if the --path flag is specified.

$ pack build sample-app --builder cnbs/sample-builder:jammy --path apps/java-maven
jammy: Pulling from cnbs/sample-builder
Digest: sha256:9db376e26252b6cbc75190c88ea24571da36ec0d373136be233b32fd174962fc
Status: Image is up to date for cnbs/sample-builder:jammy
...

Documentation

• Should this change be documented?
  • Yes, see #___
  • No

Related

Resolves #2231

[hhiroshell]

I'm thinking about adding some test cases for when the pack build is executed with the --path flag.
Please give me some time before proceeding with the review.

→ Done.

[hhiroshell]

All the changes are complete, so please review them!

[hhiroshell]

With the latest two commits(cee65f2, 59a0abf) I made, the behavior of the pack build has changed as below:

pack build warns it if both of the following criteria are met:

• A local path with the same string as the specified image name exists
• The --path flag is not used.

$ test -e apps/java-maven && echo "exists" || echo "does not exist"
exists

$ pack build apps/java-maven --builder cnbs/sample-builder:jammy
Warning: You are building an image named 'apps/java-maven'. If you mean it as an app directory path, run 'pack build <args> --path apps/java-maven'
jammy: Pulling from cnbs/sample-builder
Digest: sha256:9db376e26252b6cbc75190c88ea24571da36ec0d373136be233b32fd174962fc
Status: Image is up to date for cnbs/sample-builder:jammy
...

pack build doesn't warn it if a local path with the same string as the specified image name doesn't exist.

$ test -e aaaa && echo "exists" || echo "does not exist"
does not exist

$ pack build aaaa --builder cnbs/sample-builder:jammy
jammy: Pulling from cnbs/sample-builder
Digest: sha256:9db376e26252b6cbc75190c88ea24571da36ec0d373136be233b32fd174962fc
Status: Image is up to date for cnbs/sample-builder:jammy
...

pack build doesn't warn it if a local path with the same string as the specified image name exists, and --path is used.

$ test -e apps/java-maven && echo "exists" || echo "does not exist"
exists

$ pack build apps/java-maven --path apps/java-maven --builder cnbs/sample-builder:jammy
jammy: Pulling from cnbs/sample-builder
Digest: sha256:9db376e26252b6cbc75190c88ea24571da36ec0d373136be233b32fd174962fc
Status: Image is up to date for cnbs/sample-builder:jammy
...

[hhiroshell]

A path created by os.MkdirTemp() on macOS is like: /var/folders/vh/0l94sp8n6hx8qwhb6wsy_xrh0000gr/T/tmp.4ffiJJd5rq
It triggers an error in the validation of the image name when specified as a positional argument (image name), and results in test failure.

[jjbustamante]

Are we creating the my-app-dir folder in the current directory? if for some reason the test fails and I am running the tests locally, will I see this new my-app-dir like a new file not being tracked by git?

[natalieparellano]

I agree that creating a new directory in the local source is a bit weird. An alternative would be to invoke pack build testdata since (I'm pretty sure) this test runs in the context of /internal/commands/. We could also try some combination of os.MkdirTemp and os.Chdir to create a directory with a sensible reference, but that might be a bit heavy-handed for what we need.

[hhiroshell]

@jjbustamante @natalieparellano
Thank you for your comments and suggestions! I'll try to fix it to use the testdata. 🙏

[hhiroshell]

Done: 3aee96e

Now the code looks clean, and there will be no residue left in case of test failures. 😌

[hhiroshell]

@natalieparellano
I believe all comments have been resolved. Would you please confirm that?

If I need to explain some recent changes (#2256 (comment), #2256 (comment) ), I'll happily do so. So please let me know.

[natalieparellano]

@hhiroshell thank you for your work on this, and apologies for being slow to get back to you with a review. I think we should address the concern here: #2256 (comment) (added some suggestions)