Exit with status code 1 if cosign is not configured

[atanasdinov]

Please check below, if the PR fulfills these requirements:

• The commit message follows the guidelines.
• Tests for the changes have been added (for bug fixes / features).
• Docs have been added / updated (for bug fixes / features).

What kind of change does this PR introduce?

• Fails early if cosign is not available. For reference: [BUG] improper exit code on failed command #185

What is the current behavior?

• If cosign is not properly configured, Hauler will proceed the execution and fail at a later stage:

8:16AM ERR Error: open binaries/cosign-linux-amd64: file does not exist

8:16AM INF syncing [content.hauler.cattle.io/v1alpha1, Kind=Images] to store
8:16AM ERR Error (attempt 1/3): error adding image to store: fork/exec /root/.hauler/cosign: no such file or directory, output:
8:16AM ERR Error (attempt 2/3): error adding image to store: fork/exec /root/.hauler/cosign: no such file or directory, output:
8:16AM ERR Error (attempt 3/3): error adding image to store: fork/exec /root/.hauler/cosign: no such file or directory, output:
Error: operation failed after 3 attempts
Usage:
  hauler store sync [flags]

What is the new behavior (if this is a feature change)?

• Hauler will abort execution if cosign is not found / stored at the necessary path.

Does this PR introduce a breaking change?

• No.

[atanasdinov]

Another approach would be to move this check only to the relevant subcommands e.g. info doesn't seem to require it. Let me know how you'd prefer to handle this.

[amartin120]

@atanasdinov I'm perfectly fine with this solution, but I'm concerned about why cosign would not get configured correctly?

8:16AM ERR Error: open binaries/cosign-linux-amd64: file does not exist

I can confirm that the binary does exist within Hauler to be able to extract and put it <home>/.hauler. So I'm pretty surprised to see this.

[atanasdinov]

Hi, @amartin120. This came up with our RPM packaging for Hauler. We didn't use the proper path for cosign which in turn contributed to the binary being properly compiled but not working @ runtime.