inspector: listen on process.debugPort

[cjihrig]

Checklist

• make -j4 test (UNIX), or vcbuild test nosign (Windows) passes
• commit message follows commit guidelines

Affected core subsystem(s)

inspector

Description of change

This commit consolidates the debugging port used by the inspector and Node's legacy debugger. This eliminates any chance of the two debuggers working side by side, but the inspector is currently an unofficial feature, and the legacy debugger should eventually be removed in favor of it.

Fixes: #8201

[jasnell]

LGTM if CI is green.

[addaleax]

@cjihrig this needs a rebase :)

[cjihrig]

@addaleax rebased. Sorry for the delay. PTAL

[cjihrig]

And CI: https://ci.nodejs.org/job/node-test-pull-request/3991/

[cjihrig]

CI failures look unrelated. Since this is semver major, can another CTC member take a look? Perhaps @ofrobots?

[cjihrig]

ping @nodejs/ctc, please.

[bnoordhuis]

LGTM

[indutny]

LGTM

[cjihrig]

Final CI came back OK: https://ci.nodejs.org/job/node-test-pull-request/4040/

[ofrobots]

Sorry that I missed the ping on this. The use of different ports between inspector and the old debug protocol was quite intentional due to (very valid) concerns raised by the Debugger implementers: See original PR: #7212.

[cjihrig]

Was this it?

We should use a different default port number for the new debug
protocol. This makes it easier for debuggers to guess which protocol
they are expected to use to talk to a node process with a debug
server.

Given that you can set the port manually, wouldn't debuggers have to be able to determine which protocol was being used with 100% certainty?

[ofrobots]

The issue is that some debuggers support both the old protocol and new, and when a user requests that the debugger attach to a running process at port 5858, the debugger has no way of knowing with protocol to use. I think this was originally requested by the VSCode folks, but I can't seem to find the discussion (/cc @joshgav, @nojvek).

[joshgav]

Discussion on side-by-side ongoing at #8464, would appreciate input from you all there.

[joshgav]

/cc @nodejs/diagnostics

[ofrobots]

#8550.