WIP: Implement 1459203 (remove NSSM), 1436274 (use eventlog)

[milescrabill]

There's a ton here. Too much!

• adds dependency on gopkg.in/natefinch/lumberjack.v2 for logfile management

• removes NSSM and modifies docs, userdata in worker_types, etc. as such

• changes the way the main RunWorker function is called for flexibility, it now accepts a signal chan

• split out config handling and exit code handling into functions

• adds debug logic for panic scenario exits including writing out a crash log in scenarios where other logging might be failing

• support for installing/removing the generic worker service using native go

• support for specifying configuration location at install time

• support for windows event log when run as a service

• logging to logfile by default in windows

• remove need for a bat script wrapper to change the service working directory, cwd is set to parent dir of worker exe

Usage testing:

• verify: starting the service in interactive mode [x]
• verify: starting the service as a service works properly [x]
• verify: under expected use, can ctrl-c to properly exit from interactive mode []
  • caveat: not running as LocalUser sticks us into a loop that cannot be broken by interrupts!

TODO:

• fix CI
• actually write tests
• niceify commits
• test: install the service, verify the service exists, verify the event log source exists, remove the service
• test: starting the service without the event log source in non-interactive mode should fail with exit code 78
• test: adding a broken io.Writer to the logWriter MultiWriter will be caught (worth testing?)
• should logfile location be configurable? (currently: generic-worker.log, rotated by lumberjack)
• should logfile management be in scope or is that an infra concern?

Weird things:

• running in interactive mode prints an extra blank newline in between log entries

[coveralls]

Coverage decreased (-45.9%) to 31.164% when pulling 41bcfbc on milescrabill:no-more-nssm-merge-20190619 into 73bc174 on taskcluster:master.

[petemoore]

Nice work so far!

[milescrabill]

Closing in favor of a branch on this repo for proper testing.