Failure of "minikube ip" returns "<nil>" with exit code 0

[pre]

Steps to reproduce the issue:

1. Have cluster on not-ready state
2. Run "minikube ip"

Expected: exit code != 0 with empty output

Actual: exit code == 0
Output: <nil>

% minikube ip
<nil>
% echo $?
0

Minikube v1.11.0

Why is this a problem?
When minikube ip is used in a script, it'd be straightforward to read the exit code for whether the command succeeded. However, now the exit code is always "success" so the script needs to check for failure against a flaky string <nil> which may change at a later Minikube release.

[afbjorklund]

@pre : thanks for reporting this issue, it should not return nil like that. Which OS and which driver did this happen with ?

[afbjorklund]

The problem is in the ControlPlaneEndpoint, which doesn't check the hostname or the return value of net.ParseIP

func ParseIP(s string) IP
ParseIP parses s as an IP address, returning the result. The string s can be
in dotted decimal ("192.0.2.1") or IPv6 ("2001:db8::68") form. If s is not a
valid textual representation of an IP address, ParseIP returns nil.

[pre]

In case it matters, I have Minikube v1.11.0 on MacOS 10.15.5 with Hyperkit.

[Dean-Coakley]

I'm taking a look at fixing this. But it's my first minikube contribution so if someone wants to take it first/take it over, let me know.

[medyagh]

@Dean-Coakley are you still interested in making a PR for this ?

[medyagh]

cc: @sharifelgamal

[Dean-Coakley]

@medyagh I opened a PR that seems to resolve the issue.