This document discusses using plain Linux bridges for networking Docker containers on Kubernetes clusters deployed on OpenStack. It involves pre-allocating IP addresses on virtual machines, configuring Docker bridges to use the pre-allocated subnet, and allowing Kubernetes pods and containers to use the pre-allocated IP addresses for networking. The approach aims to provide a simple networking solution that is compatible with legacy systems.

1. K8S ON
OPENSTACK
DOCKER NETWORKING ON
OPENSTACK NEUTRON
@ Kakao Corp.이 승
Known as Niko Bellic

2. KUBERNETES
Manage a cluster of Linux containers as a single system to
accelerate Dev and simplify Ops.

3. K8S PODS
co-located group of containers and volumes
each Pod requires dedicated IP

4. COMMON PRACTICE
overlay network : slow & complicated
NAT : not compatible with legacy systems
Let's use Plain Old Linux Bridge.

5. PRE-ALLOCATE IPS ON VM

6. NEUTRON INFO
$ neutron port-list
+-----+------+-------------------+-----------------------------------------------
| id | name | mac_address | fixed_ips
+-----+------+-------------------+-----------------------------------------------
| XXX | cite | xx:xx:xx:xx:xx:xx | {"subnet_id": "...", "ip_address": "172.16.128
| | | | {"subnet_id": "...", "ip_address": "172.16.128
| | | | {"subnet_id": "...", "ip_address": "172.16.128
| | | | {"subnet_id": "...", "ip_address": "172.16.128
| | | | {"subnet_id": "...", "ip_address": "172.16.128
| | | | {"subnet_id": "...", "ip_address": "172.16.128
| | | | {"subnet_id": "...", "ip_address": "172.16.128
| | | | {"subnet_id": "...", "ip_address": "172.16.128
| | | | {"subnet_id": "...", "ip_address": "172.16.128
| | | | {"subnet_id": "...", "ip_address": "172.16.128
| | | | {"subnet_id": "...", "ip_address": "172.16.128
| | | | {"subnet_id": "...", "ip_address": "172.16.128
| | | | {"subnet_id": "...", "ip_address": "172.16.128
| | | | {"subnet_id": "...", "ip_address": "172.16.128

7. DOCKER NETWORK
cite-node-01:~$ docker network inspect bridge
[
{
"Name": "bridge",
"Id": "686c7352a697c038d642d2db95efadfc221c9e9044877b0f7a38756f5dc22e59"
"Scope": "local",
"Driver": "bridge",
"IPAM": {
"Driver": "default",
"Config": [
{
"Subnet": "172.16.128.0/23",
"IPRange": "172.16.128.128/28",
"AuxiliaryAddresses": {
"DefaultGatewayIPv4": "172.16.128.1"
}
}
]

8. K8S POD
$ kubectl get pod EXAMPLE -o yaml
apiVersion: v1
kind: Pod
metadata:
...
spec:
containers:
...
status:
...
hostIP: 172.16.217.246
phase: Running
podIP: 172.16.128.132

9. CONTAINER INFO
$ docker inspect 820ee00d9b3396572adb4c376bb5ff3a9d45c515e597267e1621401f6add297a
[
{
...
"NetworkSettings": {
"Gateway": "172.16.128.1",
"IPAddress": "172.16.128.132",
"IPPrefixLen": 23,
"IPv6Gateway": "",
"MacAddress": "02:42:ac:10:80:84",
"Networks": {
"bridge": {
"Gateway": "172.16.128.1",
"IPAddress": "172.16.128.132",
"IPPrefixLen": 23,
"IPv6Gateway": "",
"GlobalIPv6Address": "",
"GlobalIPv6PrefixLen": 0,

10. DEMO

11. QUESTIONS?