impl(gax-internal): use universe_domain when creating gRPC/HTTP transport

[alvarowolfx]

Towards #3646

[codecov]

Codecov Report

❌ Patch coverage is 96.55172% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 97.73%. Comparing base (df1db4d) to head (70e57b0).
⚠️ Report is 21 commits behind head on main.

Files with missing lines	Patch %	Lines
src/gax-internal/src/host.rs	92.98%	4 Missing ⚠️
src/gax-internal/src/http.rs	97.72%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5302      +/-   ##
==========================================
- Coverage   97.74%   97.73%   -0.01%     
==========================================
  Files         216      216              
  Lines       47482    47601     +119     
==========================================
+ Hits        46412    46525     +113     
- Misses       1070     1076       +6     

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[dbolduc]

Aside, non-blocking: We don't need to define this more than once per crate.

And we could even put it in google-cloud-test-utils to define it once for all tests

[alvarowolfx]

Split gax changes into #5419

[dbolduc]

is private.my-custom-ud.com a thing? Or restricted.my-custom-ud.com?

In which case we would want to use like <service>.my-custom-ud.com as the host, but this would use private.my-custom-ud.com.

Duckie found b/361611906 for me. Seems like yes?

[dbolduc]

Don't be afraid to scrap this whole origin_and_header function. I wrote it and it was not my finest work.

(My memory is that I was trying to make it as efficient as possible, but (1) that is not so important for client-construction vs. like per request, (2) it made the code inflexible.).

[dbolduc]

I think this fails to strip the suffix on the .with_endpoint("foo.googleapis.com").with_universe_domain("my-custom.ud") case and then it returns "foo.custom.ud", when it should return "foo.googleapis.com".

Assuming I know what the caller is supplying to this function.

[alvarowolfx]

yeah, that's the conflicting thing that I'm stuck on this feature. You commented that before on #5302 (comment).

I'm trying to make the code look good and pass the test cases for localhost and the scenario that you described.

#[test_case("localhost:5678", "test.googleapis.com"; "emulator")]
#[test_case("https://localhost:5678", "test.googleapis.com"; "emulator with scheme")]
#[test_case("https://test.googleapis.com", "test.googleapis.com"; "GDU endpoint with universe domain") ]
#[test_case("https://test.another-universe.com", "test.another-universe.com"; "endpoint priority") ]
fn header_universe_domain(input: &str, want: &str) -> anyhow::Result<()> {
    let got = header(
        Some(input),
        "https://test.googleapis.com",
        "my-custom-universe.com",
    )?;
    assert_eq!(got, want, "input={input:?}");
    Ok(())
}