v3: improve proxy.DomainForward method signature

[ryanbekhen]

Description

I want to patch proxy.DomainForward which only works on one domain.

Case:

app.Use(proxy.DomainForward("a.example.com", "http://localhost:3000")
app.Use(proxy.DomainForward("b.example.com", "http://localhost:4000")

a.example.com will not work and only b.example.com will work.

Problem Solving:
i made it easier as below.

app.Use(DomainForward(map[string]string{
  "a.example.com":  "http://localhost:3000",
  "b.example.com":  "http://localhost:4000",
}))

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

Checklist:

• For new functionalities I follow the inspiration of the express js framework and built them similar in usage
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation - https://github.com/gofiber/docs for https://docs.gofiber.io/
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• If new dependencies exist, I have checked that they are really necessary and agreed with the maintainers/community (we want to have as few dependencies as possible)
• I tried to make my code as fast as possible with as few allocations as possible
• For new code I have written benchmarks so that they can be analyzed and improved

Commit formatting:

Use emojis on commit messages so it provides an easy way of identifying the purpose or intention of a commit. Check out the emoji cheatsheet here: https://gitmoji.carloscuesta.me/

[ryanbekhen]

@ReneWerner87 please review later.

[ReneWerner87]

But this is a breaking change
We have to think before we design exposed methods for the library

[ryanbekhen]

@ReneWerner87 so what should I do if the PR labeled Breaking Change.

[ReneWerner87]

We can not accept the improvent in v2
One possibility would be to try to make it backward compatible

[ryanbekhen]

@ReneWerner87 please look at commit 14cf4b6, I just changed the way to use DomainForward so I can add domains. Does this include Breaking change?

[ReneWerner87]

The first and second parameter of DomainForward is a complete different datatype
This is a breaking change, without compatibility to the usage before

[ryanbekhen]

@ReneWerner87 Ok thanks for the info. Does this mean it will be merged in the next minor version?

[ReneWerner87]

This means that we will be able to adjust it in the next major version at the earliest.

This will probably come out in a few months

[ryanbekhen]

@ReneWerner87 maybe I can just add documentation when using multiple domains. But do I have to remove the fork first?

[ReneWerner87]

Ok, documentation changes are okay

[ryanbekhen]

ok I will add the documentation later

[efectn]

@ryanbekhen can you create/edit a PR that targets v3 branch. I think this is nice change for v3.

[ryanbekhen]

@efectn Yes, I can. So, when can I add this feature?

[efectn]

@efectn Yes, I can. So, when can I add this feature?

When you want. I merged master into the v3 beta branch

[ryanbekhen]

@efectn Previously I added 2 features, namely proxy.DomainForward and proxy.BalancerForward. Do I add these two features to v3 or only proxy.DomainForward?

[efectn]

@efectn Previously I added 2 features, namely proxy.DomainForward and proxy.BalancerForward. Do I add these two features to v3 or only proxy.DomainForward?

They are already exists on v3-beta -> https://github.com/gofiber/fiber/blob/v3-beta/middleware/proxy/proxy.go#L176

[ryanbekhen]

@efectn I have changed the target branch to v3-beta

[efectn]

There are some linting errors that unrelated to this PR. I'll fix them later.

[efectn]

@ryanbekhen can you check my last comments

[ryanbekhen]

@efectn i have changed assertequals to require in last commit

[ryanbekhen]

@efectn I'm going to update the readme on the proxy as the signature section hasn't been updated yet.