Discourse failing to start due to docker/iptables issue

Installation
1

Trying a ./launcher start app and I get the following error:

Error response from daemon: driver failed programming external connectivity on endpoint  ():  (iptables failed: iptables --wait -t filter -A DOCKER ! -i docker0 -o docker0 -p tcp -d 172.17.0.5 --dport 80 -j ACCEPT: iptables: No chain/target/match by that name.  (exit status 1)) Error: failed to start containers:

It claims no chain/match but iptables-save shows:

:DOCKER - [0:0]
-A PREROUTING -m addrtype --dst-type LOCAL -j DOCKER
-A OUTPUT ! -d 127.0.0.0/8 -m addrtype --dst-type LOCAL -j DOCKER
-A POSTROUTING -s 172.17.0.0/16 ! -o docker0 -j MASQUERADE
-A POSTROUTING -s 172.17.0.2/32 -d 172.17.0.2/32 -p tcp -m tcp --dport 443 -j MASQUERADE
-A POSTROUTING -s 172.17.0.3/32 -d 172.17.0.3/32 -p tcp -m tcp --dport 5432 -j MASQUERADE
-A POSTROUTING -s 172.17.0.2/32 -d 172.17.0.2/32 -p tcp -m tcp --dport 80 -j MASQUERADE
-A POSTROUTING -s 172.17.0.4/32 -d 172.17.0.4/32 -p tcp -m tcp --dport 80 -j MASQUERADE
-A POSTROUTING -s 172.17.0.5/32 -d 172.17.0.5/32 -p tcp -m tcp --dport 80 -j MASQUERADE
-A DOCKER -i docker0 -j RETURN
-A DOCKER ! -i docker0 -p tcp -m tcp --dport 443 -j DNAT --to-destination 172.17.0.2:443
-A DOCKER ! -i docker0 -p tcp -m tcp --dport 5432 -j DNAT --to-destination 172.17.0.3:5432
-A DOCKER ! -i docker0 -p tcp -m tcp --dport 80 -j DNAT --to-destination 172.17.0.2:80
-A DOCKER ! -i docker0 -p tcp -m tcp --dport 8086 -j DNAT --to-destination 172.17.0.4:80
-A DOCKER ! -i docker0 -p tcp -m tcp --dport 8087 -j DNAT --to-destination 172.17.0.5:

Any idea how to fix without having to restart docker service?

2

I think this was to a funny timing quirk where starting/stopping container rapidly messed up the NAT tables.

I gave up and restarted the docker service.