feat(jmx): re-implement enhanced transient JMX credentials

[andrewazores]

Fixes #523 . See there for a description of why this change is useful/necessary and the historical context.

TODO later, maybe: implement a client-side keyring. ie store the JMX credentials in local storage with a user-provided encryption key.

[maxcao13]

Everything else looks good, the ability to choose whether credentials are stored in backend or per session works well, there is something somewhat unrelated but there seems to be a memory-leak with the JMXAuthForm (but is a component in AuthModal) even though it wasn't touched in this PR.

This gets printed to the console

Warning: Can't perform a React state update on an unmounted component. This is a no-op, but it indicates a memory leak in your application. To fix, cancel all subscriptions and asynchronous tasks in a useEffect cleanup function.
JmxAuthForm@webpack-internal:///./src/app/AppLayout/JmxAuthForm.tsx:53:54
// etc... etc...

I think it's just that this subscription on line 61 isn't closed.

  const handleSave = React.useCallback(() => {
    props.onSave(username, password).then(() => {
      clear();
      context.target.setAuthRetry(); // <--------------
    });
  }, [context, context.target, clear, props.onSave, username, password]);

[andrewazores]

I think it's just that this subscription on line 61 isn't closed.

Hmm, I don't think there's a subscription there... that method just returns void.

@tthvo has seen and investigated these "state update on an unmounted component" messages lately. Any insights here?

[maxcao13]

Oh, whoops my bad, then it's something else internal then I guess, hm...

[tthvo]

I think it's just that this subscription on line 61 isn't closed.

Hmm, I don't think there's a subscription there... that method just returns void.

@tthvo has seen and investigated these "state update on an unmounted component" messages lately. Any insights here?

Ohh yesss, here:

cryostat-web/src/app/AppLayout/JmxAuthForm.tsx

Line 60 in ec23856

clear();

There is a call to setState in JMXAuthForm to clear input. However, when saving, the modal is already closed (perhaps unmount its body and remove from tree internally ), this call will be invalid since calling on unmounted components.

To fix, just remove it as it is not needed as the form is mounted fresh anyway.

[tthvo]

Looks good! Just a couple comments. Also, it seems there are no current unit tests for this Setting view. I think we should add them :D

[tthvo]

Looks great to me!