Panic at startup on the latest docker image about oauth2-proxy

[ploxiln]

the issue is that #92 updated the version of github.com/mreiferson/go-options being used

[Berjou]

Indeed. This is the exact commit that cause the issue: mreiferson/go-options@0c63f02.
* use Get() rather than String() for flag values

[Berjou]

The panic is raised line 86 of https://github.com/mreiferson/go-options/blob/master/options.go:

v = flagInst.Value.String() -> v = flagInst.Value.(flag.Getter).Get()

However, flagInst.Value does not implement the Getter interface. I'm completely inexperimented in Go, but for my understanding, the problem here is that in https://github.com/pusher/oauth2_proxy/blob/master/main.go, we have

emailDomains := StringArray{}
whitelistDomains := StringArray{}
upstreams := StringArray{}
skipAuthRegex := StringArray{}
googleGroups := StringArray{}

and then, we pass these variables to flagSet.Var(), but a StringArray() does not implement the Getter interface.

[ploxiln]

That is correct, a Get() method needs to be added for the StringArray type

[flowstate]

I added a Get() to StringArray and it still failed exactly the same way:

// StringArray is a type alias for a slice of strings
type StringArray []string

// Set appends a string to the StringArray
func (a *StringArray) Set(s string) error {
	*a = append(*a, s)
	return nil
}

// String joins elements of the StringArray into a single comma separated string
func (a *StringArray) String() string {
	return strings.Join(*a, ",")
}

func (a *StringArray) Get() string {
	return strings.Join(*a, ",")
}

However, my go is very rusty, so I could be missing a reason this fails.

[ploxiln]

Get() needs to return interface{} explicitly.

There is actually another project with the same type and usage which adapted for this first:
https://github.com/nsqio/nsq/blob/master/internal/app/string_array.go

[Berjou]

I have just tested the latest docker image, this issue seems to be solved.

[JoelSpeed]

Thanks 😀