Add Docker TM Compose for load testing

[rob05c]

Adds Docker Traffic Monitor Compose file, designed for load testing
the Traffic Monitor. Starts a DB, TO, and TM, configured with a
given SQL TO dump, and starts the Monitor polling the servers
in TO from the SQL file.

[asfgit]

Refer to this link for build results (access rights to CI server needed):
https://builds.apache.org/job/incubator-trafficcontrol-PR/849/
Test FAILed.

[asfgit]

Refer to this link for build results (access rights to CI server needed):
https://builds.apache.org/job/incubator-trafficcontrol-PR/850/
Test PASSed.

[limited]

I pulled these changes in to test it out, but I'm not really clear on what the pre-reqs are for this.

• TO RPM
• TM RPM
• Dump of functioning TO database with active servers registered.
• Enough active servers to load down the TM (how many is this??)
• I haven't gotten this far, but I assume astats has to be configured on those servers to whitelist the new TM IP?

The overhead on getting this test running is pretty high, it would be great if we could bring this barrier down to not require a TO dump. Maybe this could also include some way of generating load on the TM without the need for n caches?

I'll try to grab a dump of my dev setup TM with a single cache and give this another try later today. Once I get it running, I'll merge as is and it can always be improved later

[limited]

Got the following error building traffic_monitor_load_test_traffic_ops_database image:

 ---> Running in 2b78254facc3
Can't locate CPAN.pm in @INC (you may need to install the CPAN module) (@INC contains: /etc/perl /usr/local/lib/x86_64-linux-gnu/perl/5.24.1 /usr/local/share/perl/5.24.1 /usr/lib/x86_64-linux-gnu/perl5/5.24 /usr/share/perl5 /usr/lib/x86_64-linux-gnu/perl/5.24 /usr/share/perl/5.24 /usr/local/lib/site_perl /usr/lib/x86_64-linux-gnu/perl-base .).
BEGIN failed--compilation aborted.
ERROR: Service 'traffic_monitor_test_load_traffic_ops_database' failed to build: The command '/bin/sh -c perl -MCPAN -e 'my $c = "CPAN::HandleConfig"; $c->load(doit => 1, autoconfig => 1); $c->edit(prerequisites_policy => "follow"); $c->edit(build_requires_install_policy => "yes"); $c->commit'' returned a non-zero code: 2

[rob05c]

Yeah, it currently needs a DB dump, just to get TO running. Maybe we can script creating everything we need, or maybe we can sanitize a sql dump and include the file in the repo.

It looks like traffic_ops_database/Dockerfile broke. Not sure what changed since I made the PR. Maybe the postgres:9.6 image changed, or maybe your CPAN is different from what I used, not sure.

I'll try to find time to look at it, but to be honest, it's not a high priority for me right now. I do think automated load testing of the monitor would be highly valuable. We just have too many high priority things at the moment.