Added function to use a config directory other than .onos

[AntonJoha]

Hi.

I am not sure if this project is still under active use or if a pull request is appreciated.
But I found that the logging library here gave us with a simple method of logging to a Kafka broker.

The only issue I had is that we in our project would like to save all configurations in the same directory, meaning that the standard ".onos" folder is a hard no.

This pull request aims to fix that by introducing the function CustomInit function.
It gives the user of the library a chance of initializing with a custom directory name.

This is done in our case with a wrapper library which calls CustomInt in the init function.
The wrapper library can then be added to use a custom directory.
Code below is how the basic wrapper could look

import (
	logging "github.com/onosproject/onos-lib-go/pkg/logging"
)
func init() {
    logging.CustomInit(".myconfig")
}
func GetLogger(names ...string) logging.Logger {
    return logging.GetLogger(names)
}

This means that the init function in the file pkg/logging/logger.go had to be removed, else it would init on load before the user can call CustomInit.
A nil check for the variable root has been added in the function GetLogger to handle the cases where a user doesn't want to use the CustomInit function.
This means that users which want the library to work the same as before can simply call the GetLogger and get the same expected behaviour.
This adds an extra check every time the function is called which is extra overhead. But I'm not sure if that amount is of any care to the project?

Again, I don't know if anyone still manages this repository and if pull requests are appreciated.
I'd be happy to change the code or further explain my reasoning if anyone is interest!
Thank you for taking the time to read this.

[onf-bot]

Can one of the admins verify this patch?

[SeanCondon]

retest this please

[SeanCondon]

this is giving a build error

09:12:32 pkg/logging/config.go:278: File is not `gofmt`-ed with `-s` (gofmt)
09:12:32 
09:12:32 pkg/logging/logger.go:19:1: exported: exported function CustomInit should have comment or be unexported (revive)
09:12:32 func CustomInit(dir string) {
09:12:32 ^

[AntonJoha]

this is giving a build error

09:12:32 pkg/logging/config.go:278: File is not `gofmt`-ed with `-s` (gofmt)
09:12:32 
09:12:32 pkg/logging/logger.go:19:1: exported: exported function CustomInit should have comment or be unexported (revive)
09:12:32 func CustomInit(dir string) {
09:12:32 ^

If you're interested then I could set aside time to fix it in a day or two

[SeanCondon]

If you're interested then I could set aside time to fix it in a day or two
OK - it's just that I don't think anyone will review it if it's not passing tests

[gab-arrobo]

ok to test

[AntonJoha]

ok to test

Sorry, forgot about this PR, pushed a commit to pass the comment requirement check.

[gab-arrobo]

@AntonJoha you need to apply gofmt to the files you are updating. That is:
gofmt -w pkg/logging/config.go and gofmt -w pkg/logging/logger.go

[gab-arrobo]

@SeanCondon, what are your thoughts about this PRs?

[SeanCondon]

I think it would be simpler to have changed line 12 to load configdir from an environment variable. If not present it can be .onos by default, so as not to break existing functionality.
Reading of this env var could be done in the init() function

[AntonJoha]

What existing behaviour does it break? I guess using a env-var is up to personal style so don't mind that part.

I didn't mention it earlier but the init function is (as far as I can see) a bit of an issue as well. As it contains code in its path that can panic. It is to my knowledge not possible to handle this panic.

[SeanCondon]

Fair point on the panic inside init().
As far as existing functionality is concerned - I mean existing uses expect a default value .onos if not ENV VAR is present