Multicast source address affected by weave expose

[bboreham]

I have a small demo program that prints the hostname and source address of other multicasters.

host1$ weave launch 192.168.48.12
host2$ weave launch 192.168.48.11
host1$ weave run --name=c1 bboreham/mweb
host2$ weave run --name=c2 bboreham/mweb
host1$ curl `docker inspect -f {{.NetworkSettings.IPAddress}} c1`:8080
c1.weave.local 10.32.0.1:57206
c2.weave.local 10.40.0.0:45872
host2$ curl `docker inspect -f {{.NetworkSettings.IPAddress}} c2`:8080
c1.weave.local 10.32.0.1:57206
c2.weave.local 10.40.0.0:45872

So far so good. Run weave expose, and nothing changes:

host1$ weave expose
10.32.0.2
host1$ curl `docker inspect -f {{.NetworkSettings.IPAddress}} c1`:8080
c1.weave.local 10.32.0.1:57206
c2.weave.local 10.40.0.0:45872

But now run a new container:

host1$ weave run --name=c3 bboreham/mweb
266568a679e4252f75a9617ea67ecb2fab610f5e6ae139018ec1edf0e273cf2f
host1$ curl `docker inspect -f {{.NetworkSettings.IPAddress}} c1`:8080
c1.weave.local 10.32.0.1:57206
c2.weave.local 10.40.0.0:45872
c3.weave.local 10.32.0.2:53622

so now c3 is being reported at the weave expose address. Same on the other host:

host2$ curl `docker inspect -f {{.NetworkSettings.IPAddress}} c2`:8080
c2.weave.local 10.40.0.0:45872
c3.weave.local 10.32.0.2:53622
c1.weave.local 10.32.0.1:57206

weave hide puts it back to normal again:

host1$ weave hide
10.32.0.2
host1$ curl `docker inspect -f {{.NetworkSettings.IPAddress}} c1`:8080
c1.weave.local 10.32.0.1:57206
c2.weave.local 10.40.0.0:45872
c3.weave.local 10.32.0.3:53622

[bboreham]

Compare #605

[bboreham]

Fixed by #2158