Deal with V8 debugger protocol going away

[BobDickinson]

Node has had a V8 debugging protocol built in from the start (this is a thin network protocol layer on top of the actual internal V8 debugger protocol). That is what Synchro Server currently uses to debug Synchro apps (typically by launching Synchro apps as child processes, each listening for debug on their own ports).

That V8 debugger support has been semi-supported to non-supported for quite a while, and appears to be going away entirely in 8.0 (we get a deprecation warning starting in latter 7.x releases).

https://twitter.com/jasnell/status/816690727988015108

The "old" V8 debugger protocol support is being replaced by something called "V8_inspector", which is the protocol used by the Chrome debugger (allowing Node apps to be debugged using Chrome - which is a great solution). Here are a couple of relevant issues:

Add V8_inspector support - nodejs/node#6792

Discussion of v8_inspector in Node 6.x - nodejs/node#7072

If we want to maintain our built-in debugger, then we need to support the V8_inspector protocol (probably in addition to the old debugger client, so we can support old and new versions of Node).

If we look at how the Chrome debugger works when debugging Synchro apps and we're happy with that, maybe we just punt on having our own debugger entirely.

Either way, the debugger in Synchro Studio as currently implemented is not going to work in Node 8.0 and later.

[BobDickinson]

@bcr reports:

FYI with Node sometime after 7.6.0 we are pooping this out:

[2017-03-14 13:58:18.330] [INFO] synchro-api - Creating API processor for app at path: samples, debug port is: 6868
(node:59937) DeprecationWarning: node --debug is deprecated. Please use node --inspect instead.
Debugger listening on 127.0.0.1:6868