fix: login and logout will leverage docker config and os default store

[Wwwsylvia]

Fixes: #696

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Behaviors of this PR

• If the notation config has auth configuration
  • Use the notation config for credentials GET, PUT and DELETE
• If the notation config does not have auth configuration, or the the notation config file does not exist
  • If the docker config has auth configuration
    • Use the notation config for credentials GET, PUT and DELETE
  • If there is no authentication configured in the docker config, or the the docker config file does not exist
    • If there is a platform-default native keychain installed
      • Use the platform-default native keychain for credentials GET, PUT and DELETE
    • If there is no platform-default native keychain installed
      • GET will always return an empty credential
      • PUT will always fail (ErrPlaintextPutDisabled)
      • DELETE will result in no operation

[codecov-commenter]

Codecov Report

Merging #712 (b612e92) into main (c9d3997) will decrease coverage by 0.26%.
The diff coverage is 0.00%.

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@@            Coverage Diff             @@
##             main     #712      +/-   ##
==========================================
- Coverage   63.77%   63.52%   -0.26%     
==========================================
  Files          40       40              
  Lines        2228     2237       +9     
==========================================
  Hits         1421     1421              
- Misses        686      695       +9     
  Partials      121      121              

Impacted Files	Coverage Δ
cmd/notation/login.go	25.00% <ø> (ø)
internal/auth/credentials.go	0.00% <0.00%> (ø)

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[Wwwsylvia]

Binary for testing: https://github.com/Wwwsylvia/notation/releases/tag/v1.0.9-sylvia

[shizhMSFT]

It seems that we were on the wrong track as we were figuring out the auth from the perspective of oras instead of notation.

For the consideration of notation, should we think about the following decision table?

ID	Is Notation config auth configured?	Is Docker config auth configured?	Decision
1	No	No	Detect default native store for GET, PUT, and DELETE
2	Yes	No	Use Notation config only for GET, PUT, and DELETE. If plaintext cred is configured but cred store is not configured, fail on PUT.
3	No	Yes	Use docker config only for GET, PUT, and DELETE. If plaintext cred is configured but cred store is not configured, fail on PUT.
4	Yes	Yes	Use Notation config only for GET, PUT, and DELETE. If plaintext cred is configured but cred store is not configured, fail on PUT.

Here are detailed descriptions:

1. No auth configured at all. In this case, we should detect and use the default native store for better OOBE.
2. Notation auth config is configured but docker is not. This is a typical scenario where docker is not installed. In this case, we should use the notation auth config only.
3. Notation auth config is not configured but docker is. This is a typical scenario where docker is installed and users want to share the docker auth with notation.
4. Both notation auth config and docker auth config are configured. This is a typical scenario that users want to use notation as an isolated and independent component from docker.

[shizhMSFT]

LGTM

[priteshbandi]

LGTM