fix: error message for verify-attestation command avoid to print help message

[developer-guy]

Signed-off-by: Batuhan Apaydın batuhan.apaydin@trendyol.com
Co-authored-by: Furkan Türkal furkan.turkal@trendyol.com
Co-authored-by: Erkan Zileli erkan.zileli@trendyol.com
Co-authored-by: Ahmet Avcı ahmet.avci@trendyol.com
Co-authored-by: Yasin Taha Erol yasintaha.erol@trendyol.com
Co-authored-by: Emin Aktaş emin.aktas@trendyol.com

Summary

This error causes to print help message of the command to stdout, so we fixed the error message by returning nil.

Before

There are 1 number of errors occurred during the validation:
- rego validation failed
Error: 1 validation errors occurred
Usage:
  cosign verify-attestation [flags]

Examples:
  cosign verify-attestation --key <key path>|<key url>|<kms uri> <image uri> [<image uri> ...]

  # verify cosign attestations on the image
  cosign verify-attestation <IMAGE>

  # verify multiple images
  cosign verify-attestation <IMAGE_1> <IMAGE_2> ...

  # additionally verify specified annotations
  cosign verify-attestation -a key1=val1 -a key2=val2 <IMAGE>

  # (experimental) additionally, verify with the transparency log
  COSIGN_EXPERIMENTAL=1 cosign verify-attestation <IMAGE>

  # verify image with public key
  cosign verify-attestation --key cosign.pub <IMAGE>

  # verify image with public key provided by URL
  cosign verify-attestation --key https://host.for/<FILE> <IMAGE>

  # verify image with public key stored in Google Cloud KMS
  cosign verify-attestation --key gcpkms://projects/<PROJECT>/locations/global/keyRings/<KEYRING>/cryptoKeys/<KEY> <IMAGE>

  # verify image with public key stored in Hashicorp Vault
  cosign verify-attestation --key hashivault:///<KEY> <IMAGE>

Flags:
      --allow-insecure-registry                                                                  whether to allow insecure connections to registries. Don't use this for anything but testing
      --attachment-tag-prefix [AttachmentTagPrefix]sha256-[TargetImageDigest].[AttachmentName]   optional custom prefix to use for attached image tags. Attachment images are tagged as: [AttachmentTagPrefix]sha256-[TargetImageDigest].[AttachmentName]
      --check-claims                                                                             whether to check the claims found (default true)
      --fulcio-url string                                                                        [EXPERIMENTAL] address of sigstore PKI server (default "https://fulcio.sigstore.dev")
  -h, --help                                                                                     help for verify-attestation
      --identity-token string                                                                    [EXPERIMENTAL] identity token to use for certificate from fulcio
      --key string                                                                               path to the private key file, KMS URI or Kubernetes Secret
  -o, --output string                                                                            output format for the signing image information (json|text) (default "json")
      --policy strings                                                                           specify CUE or Rego files will be using for validation
      --rekor-url string                                                                         [EXPERIMENTAL] address of rekor STL server (default "https://rekor.sigstore.dev")
      --sk                                                                                       whether to use a hardware security key
      --slot string                                                                              security key slot to use for generated key (default: signature) (authentication|signature|card-authentication|key-management)
      --type string                                                                              specify a predicate type (slsaprovenance|link|spdx|custom) or an URI (default "custom")

Global Flags:
      --output-file string   log output to a file
  -d, --verbose              log debug output

main.go:48: error during command execution: 1 validation errors occurred

After

[policy.rego]
will be validating against Rego policies: [policy.rego]
There are 1 number of errors occurred during the validation:
- rego validation failed

Ticket Link

Fixes

Release Note

fix: error message for verify-attestation command avoid to print help message

[dlorenc]

Nice!

[dlorenc]

Whoops - before merging, do we need the error to make sure we exit with 1?

[dlorenc]

We might want to do something like this instead: spf13/cobra#340

[dlorenc]

Yep, over here: #874

[n3wscott]

We might want to os.exit(1) to signal the command was not successful?

[dlorenc]

Yeah I think we can actually drop this change entirely and handle suppressing usage correctly in #874

[n3wscott]

#878

[n3wscott]

I opened #878 instead of this change.

[dlorenc]

I think this one can get closed now, reopen if I'm missing anything!

[developer-guy]

thank you so much @dlorenc, looks ok 👍