fly: tell user when team is invalid

[taylorsilva]

What does this PR accomplish?

closes #5624

Before 6.1.0 fly would exit 1 and display an error if the user logged in
with an invalid team. This commit brings back this behaviour.

Contributor Checklist

• Followed Code of conduct, Contributing Guide & avoided Anti-patterns
• Signed all commits
• Added tests (Unit and/or Integration)
• Updated Documentation
• Updated Release notes

Reviewer Checklist

• Code reviewed
• Tests reviewed
• Documentation reviewed
• Release notes reviewed
• PR acceptance performed
• New config flags added? Ensure that they are added to the
  BOSH and
  Helm packaging; otherwise, ignored for
  the integration
  tests
  (for example, if they are Garden configs that are not displayed in the
  --help text).

[aoldershaw]

Tested it and it seems to work, but the behaviour is a bit different than I would expect.

$ fly -t dev login -c https://127.0.0.1:8080 -u test -p test -n blah
logging in to team 'blah'


target saved
error: you are not a member of 'blah' or the team does not exist

It's weird to say target saved (and to save the target at all) if the team is invalid. What do you think about the following: instead of calling rc.SaveTarget(...) to perform the userInfo check, we instead use rc.NewTarget(...), and only after validating the user is a member of the team do we save the target.

---

EDIT

Perhaps a better way to do this would be to modify target.Validate() to also perform the user info check, and in fly login call:

target := rc.NewTarget(...)
err := target.Validate()
if err != nil {
  return err
}
err = command.saveTarget(...)
...

This way, we'd also perform the user info check for every command, so if a user is removed from a team, they'd also see an appropriate error message.

[taylorsilva]

@aoldershaw Updated so the target is NOT saved if the user is not on the team/the team doesn't exist.

---

Perhaps a better way to do this would be to modify target.Validate() to also perform the user info check, and in fly login call:

I joked with @jomsie that this function should really be called ValidateVersion() 😅
I don't want to overload this function with more responsibility. Ideally I'd like to see the API tell us that "hey that team doesn't exist or you're not a member of that team" instead of figuring it out on the client-side with an extra API call. I know the API call to /user is cheap (not as cheap as /info though) but I'd like to avoid making more and more API calls per command.

[aoldershaw]

Logging into an invalid team behaves as expected:

$ fly -t dev login -c https://127.0.0.1:8080 -u test -p test -n blah
logging in to team 'blah'


error: you are not a member of 'blah' or the team does not exist

...as does logging into a valid team:

$ fly -t dev login -c https://127.0.0.1:8080 -u test -p test -n main
logging in to team 'main'


target saved

Looks good!

[taylorsilva]

Had to rebase on master to fix release notes conflict. Review again please :)

[jamieklassen]

merge conflicts in release notes suck

[aoldershaw]

Still looks good! (I'm not seeing any changes to the code...let me know if I missed anything)