From 54f5696aebdee6f8fd63ee75f52bbf6704272ba0 Mon Sep 17 00:00:00 2001
From: Philip Garrett <philip.garrett@weather.com>
Date: Sat, 25 Feb 2017 16:09:43 -0500
Subject: [PATCH] Prevent IP collision between ELB and VMs

This creates a dedicated subnet for the ELB so its randomly assigned IPs do
not collide with the static IPs that this guide assigns to the EC2 instances.
---
 docs/01-infrastructure-aws.md | 23 ++++++++++++++++++++++-
 1 file changed, 22 insertions(+), 1 deletion(-)

diff --git a/docs/01-infrastructure-aws.md b/docs/01-infrastructure-aws.md
index c0e50a4..a4cc920 100644
--- a/docs/01-infrastructure-aws.md
+++ b/docs/01-infrastructure-aws.md
@@ -78,6 +78,21 @@ aws ec2 create-tags \
   --tags Key=Name,Value=kubernetes
 ```
 
+Create a subnet for the ELB, so its IP address doesn't collide with the VMs.
+
+```
+ELB_SUBNET_ID=$(aws ec2 create-subnet \
+  --vpc-id ${VPC_ID} \
+  --cidr-block 10.240.1.0/24 | \
+  jq -r '.Subnet.SubnetId')
+```
+
+```
+aws ec2 create-tags \
+  --resources ${ELB_SUBNET_ID} \
+  --tags Key=Name,Value=kubernetes-elb
+```
+
 ### Internet Gateways
 
 ```
@@ -117,6 +132,12 @@ aws ec2 associate-route-table \
   --subnet-id ${SUBNET_ID}
 ```
 
+```
+aws ec2 associate-route-table \
+  --route-table-id ${ROUTE_TABLE_ID} \
+  --subnet-id ${ELB_SUBNET_ID}
+```
+
 ```
 aws ec2 create-route \
   --route-table-id ${ROUTE_TABLE_ID} \
@@ -185,7 +206,7 @@ An ELB will be used to load balance traffic across the Kubernetes control plane.
 aws elb create-load-balancer \
   --load-balancer-name kubernetes \
   --listeners "Protocol=TCP,LoadBalancerPort=6443,InstanceProtocol=TCP,InstancePort=6443" \
-  --subnets ${SUBNET_ID} \
+  --subnets ${ELB_SUBNET_ID} \
   --security-groups ${SECURITY_GROUP_ID}
 ```