Improve error message when a docker image is passed to --reference

[dev-drprasad]

Describe the bug

For some reason porter explain not able to show bundle information for some bundles from https://hub.docker.com/r/getporter . I don't think its a bug. something to do with version mismatch

To Reproduce

Steps to reproduce the behavior:

1. Run porter explain --tag getporter/mysql:v0.1.1
2. You see information
3. Run porter explain --tag getporter/porter-hello-installer:0.1.0
4. You See error

Expected behavior

porter explain --tag getporter/porter-hello-installer:0.1.0 should work. right ?

Porter Command and Output

➜ porter explain --tag getporter/porter-hello-installer:0.1.0

Error: unable to pull bundle before invoking explain command: unable to pull bundle getporter/porter-hello-installer:0.1.0: unable to pull remote bundle: invalid media type "application/vnd.docker.distribution.manifest.v2+json" for bundle manifest

Version

porter v0.22.1-beta.1-14-g4401e74 (4401e74)

[carolynvs]

The problem is that getporter/porter-hello-installer is the invocation image, and explain requires that you pass in the tag for a bundle. Try the command again and pass in this instead getporter/porter-hello:v0.1.0 and you will see output

$ porter explain -t getporter/porter-hello:v0.1.0
Name: HELLO
Description: An example Porter configuration
Version: 0.1.0

No credentials defined

Parameters:
Name           Description                                                     Type      Default   Required   Applies To
porter-debug   Print debug information from Porter when executing the bundle   boolean   false     false      All Actions

No outputs defined

No custom actions defined

[carolynvs]

It would be great if porter detected the type of the image pulled, and if it's a regular docker image, it should give you a better error message like "--tag should be the tag of a bundle, but an image tag was specified".

[dev-drprasad]

I see error coming directly from dependency package: cnab-to-oci . I don't think porter can detect what type of image it is

[carolynvs]

cnab-to-oci is a dependency of ours that we can contribute to in the cnabio org, similar to cnab-go. So no worries, we aren't limited to just solutions that are within Porter's codebase.