This is to be used during migration, running on the old host so as to
forward all messages to the new Gateway.
The destination is hard-coded in `LIVE_GATEWAY_URL`.
* Use the "make an explicit Bottle() and use it" change.
* Use app.route with OPTIONS in method= list.
* Remove extraneous setting of Access-Control-Allow-Origin header.
This fixes the problem I was having (on two separate machines, Debian
stretch and Debian buster) with the Gateway not actually sending
messages out port 8500 to the Relay and Monitor.
Something about the '@thing' syntax, or using bare 'run()' must be
interfering with zmq.green. The latter ends up thinking there are no
active/matching sockets to send to[0], despite the sockets definitely
being there (complete with TCP 3-way handshake visible on tcpdump
output).
With the problem:
* no network traffic was observed on port 8500.
* A test sender.send(...) just before the bottle run() call
*did* send the message. A similar test at the start of the
@post('/upload/') function did not succeed.
[0] - I ended up putting debug prints in both python-zmq and the zeromq
'libzmq' libraries, building the Debian packages and installing those
versions. I also ended up using 'gdb' on the process. The end result
of this was to find that the _matching variable (a count of matching
sockets I think) was empty deep in libzmq, when it should be counting
sockets to send to.
This was specifically in zeromq3-4.3.1/src/dist.cpp, in the
void zmq::dist_t::distribute (msg_t *msg_) function. The immediate:
if (_matching == 0) {
test was true. I didn't manage to track down which bit of libzmq code
should have been setting _matching before I 'recursed back up' the call
chain to investigate other things.
