Docker Network Demo - Part 4

So, there's always the oops moment when you know that you did something wrong, often before you did it.

I closed one of the putty windows.  Wasn't sure how to get back to my new container. 

Update:  https://github.com/docker/docker/issues/2838 Control-P and Control-Q on the console allow you to move into and out of the psuedo-shell

As it turns out, the container is given a name (assumption that a name could be applied to it also).

docker ps - to see the running containers

nelson@lab1:~$ docker ps

CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES

4a567ec8d878        alpine              "/bin/sh"           4 hours ago         Up 4 hours                              serene_jennings

60f137369165        alpine              "/bin/sh"           18 hours ago        Up 18 hours                             nauseous_meninsky

I'm after nauseous_meninsky (have to look up where they get these names later).

nelson@lab1:~$ docker attach nauseous_meninsky

/ #

Whew!  Disaster averted.  Back in my container!

……

Getting back to the networking, the default docker network is an RFC1918 class B.  It seemed like a waste of address space to me, so let's create another network in docker.

docker network create -d bridge --subnet 172.16.1.0/24 docker1

-d is the driver, we want a bridge 

--subnet defines the network range, looks like the default gateway is always the first in the range

docker1 is the defined name, like docker0 in the ifconfig -a from the host

nelson@lab1:~$ docker network create -d bridge --subnet 172.16.1.0/24 docker1

11f4ac20d39dd523c48fe3ac6462dd8bcb4a7247dba5162bec37d46208315bc2

docker network ls - to see if it added to the networks

nelson@lab1:~$ docker network ls

NETWORK ID          NAME                DRIVER

1c9307d1163e        bridge              bridge

11f4ac20d39d        docker1             bridge

72a37254aedb        host                host

ae03349bbf0e        none                null

Let's create a container and associate it to the new network.

docker run --net=docker1 alpine -it alpine /bin/sh

nelson@lab1:~$ docker run --net=docker1 -it alpine /bin/sh

/ # ifconfig -a

eth0      Link encap:Ethernet  HWaddr 02:42:AC:10:01:02

          inet addr:172.16.1.2  Bcast:0.0.0.0  Mask:255.255.255.0

          inet6 addr: fe80::42:acff:fe10:102%32720/64 Scope:Link

          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1

          RX packets:54 errors:0 dropped:0 overruns:0 frame:0

          TX packets:8 errors:0 dropped:0 overruns:0 carrier:0

          collisions:0 txqueuelen:0

          RX bytes:11822 (11.5 KiB)  TX bytes:648 (648.0 B)

lo        Link encap:Local Loopback

          inet addr:127.0.0.1  Mask:255.0.0.0

          inet6 addr: ::1%32720/128 Scope:Host

          UP LOOPBACK RUNNING  MTU:65536  Metric:1

          RX packets:0 errors:0 dropped:0 overruns:0 frame:0

          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0

          collisions:0 txqueuelen:0

          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

/ #

nelson@lab1:~$ docker ps

CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES

2b9cacaef4f6        alpine              "/bin/sh"           36 seconds ago      Up 35 seconds                           sick_mclean

4a567ec8d878        alpine              "/bin/sh"           4 hours ago         Up 4 hours                              serene_jennings

60f137369165        alpine              "/bin/sh"           19 hours ago        Up 19 hours                             nauseous_meninsky

Now, lets see what it can talk to from the new shell.

Internet - Success

/ # ping 8.8.8.8

PING 8.8.8.8 (8.8.8.8): 56 data bytes

64 bytes from 8.8.8.8: seq=0 ttl=57 time=24.809 ms

64 bytes from 8.8.8.8: seq=1 ttl=57 time=25.089 ms

64 bytes from 8.8.8.8: seq=2 ttl=57 time=29.708 ms

^C

--- 8.8.8.8 ping statistics ---

3 packets transmitted, 3 packets received, 0% packet loss

round-trip min/avg/max = 24.809/26.535/29.708 ms

Gateway - Success

/ # ping 172.16.1.1

PING 172.16.1.1 (172.16.1.1): 56 data bytes

64 bytes from 172.16.1.1: seq=0 ttl=64 time=0.130 ms

64 bytes from 172.16.1.1: seq=1 ttl=64 time=0.117 ms

64 bytes from 172.16.1.1: seq=2 ttl=64 time=0.111 ms

^C

--- 172.16.1.1 ping statistics ---

3 packets transmitted, 3 packets received, 0% packet loss

round-trip min/avg/max = 0.111/0.119/0.130 ms

Container 1 - Failure

/ # ping 172.17.0.2

PING 172.17.0.2 (172.17.0.2): 56 data bytes

^C

--- 172.17.0.2 ping statistics ---

9 packets transmitted, 0 packets received, 100% packet loss

Container 2 - Failure

/ # ping 172.17.0.3

PING 172.17.0.3 (172.17.0.3): 56 data bytes

^C

--- 172.17.0.3 ping statistics ---

4 packets transmitted, 0 packets received, 100% packet loss

So, there's no path between 172.16.1.0/24 and 172.17.0.0/16

The routes from the host

nelson@lab1:~$ ip route

default via 192.168.123.254 dev wlan0  proto static

172.16.1.0/24 dev br-11f4ac20d39d  proto kernel  scope link  src 172.16.1.1

172.17.0.0/16 dev docker0  proto kernel  scope link  src 172.17.0.1

192.168.123.0/24 dev wlan0  proto kernel  scope link  src 192.168.123.24  metric 9

Modified for 2 bridges attached to docker

So, maybe it looks a little more like this.

http://www.abusedbits.com/2016/07/docker-network-demo-part-5.html