haproxy only logs to /dev/log; this means all our access logs get
mixed into syslog. This makes it impossible to pick out anything in
syslog that might be interesting (and vice-versa, means you have to
filter out things if analysing just the haproxy logs).
It seems like the standard way to deal with this is to have rsyslogd
listen on a separate socket, and then point haproxy to that. So this
configures rsyslogd to create /var/run/dev/log and maps that into the
container as /dev/log (i.e. don't have to reconfigure the container at
all).
We then capture this sockets logs to /var/log/haproxy.log, and install
rotation for it.
Additionally we collect this log from our tests.
Change-Id: I32948793df7fd9b990c948730349b24361a8f307