Fix issue preventing to create single-AZ nodegroups

[errordeveloper]

Description

Make sure to fetch public and private subnet IDs when getting all VPC info. This was address in #

Fixes #432. This is an improvement on what #429, but it uses CloudFormation stack outputs, since there we get subnet IDs by topologies easily.

Checklist

• Code compiles correctly (i.e make build)
• All tests passing (i.e. make test)

[errordeveloper]

 [0] >> ./eksctl create cluster --name=test-node-az-1 --nodes=1 --region=eu-north-1
[ℹ]  using region eu-north-1
[ℹ]  setting availability zones to [eu-north-1a eu-north-1c eu-north-1b]
[ℹ]  subnets for eu-north-1a - public:192.168.0.0/19 private:192.168.96.0/19
[ℹ]  subnets for eu-north-1c - public:192.168.32.0/19 private:192.168.128.0/19
[ℹ]  subnets for eu-north-1b - public:192.168.64.0/19 private:192.168.160.0/19
[ℹ]  nodegroup "ng-83dabd5f" will use "ami-06ee67302ab7cf838" [AmazonLinux2/1.11]
[ℹ]  creating EKS cluster "test-node-az-1" in "eu-north-1" region
[ℹ]  will create 2 separate CloudFormation stacks for cluster itself and the initial nodegroup
[ℹ]  if you encounter any issues, check CloudFormation console or try 'eksctl utils describe-stacks --region=eu-north-1 --name=test-node-az-1'
[ℹ]  creating cluster stack "eksctl-test-node-az-1-cluster"
[ℹ]  creating nodegroup stack "eksctl-test-node-az-1-nodegroup-ng-83dabd5f"
[✔]  all EKS cluster resource for "test-node-az-1" had been created
[✔]  saved kubeconfig as "/Users/ilya/.kube/config"
[ℹ]  nodegroup "ng-83dabd5f" has 0 node(s)
[ℹ]  waiting for at least 1 node(s) to become ready in "ng-83dabd5f"
[ℹ]  nodegroup "ng-83dabd5f" has 1 node(s)
[ℹ]  node "ip-192-168-94-149.eu-north-1.compute.internal" is ready
[ℹ]  kubectl command should work with "/Users/ilya/.kube/config", try 'kubectl get nodes'
[✔]  EKS cluster "test-node-az-1" in "eu-north-1" region is ready
 [0] >> ./eksctl create nodegroup --cluster=test-node-az-1 --nodes=1 --region=eu-north-1 --node-zones=eu-north-1c
[ℹ]  using region eu-north-1
[ℹ]  nodegroup "ng-47ff879e" will use "ami-06ee67302ab7cf838" [AmazonLinux2/1.11]
[ℹ]  will create a Cloudformation stack for nodegroup ng-47ff879e in cluster test-node-az-1
[ℹ]  creating nodegroup stack "eksctl-test-node-az-1-nodegroup-ng-47ff879e"
[ℹ]  nodegroup "ng-47ff879e" has 0 node(s)
[ℹ]  waiting for at least 1 node(s) to become ready in "ng-47ff879e"
[ℹ]  nodegroup "ng-47ff879e" has 1 node(s)
[ℹ]  node "ip-192-168-47-78.eu-north-1.compute.internal" is ready
[✔]  created nodegroup "ng-47ff879e" in cluster "test-node-az-1"
[ℹ]  will inspect security group configuration for all nodegroups
 [0] >> ./eksctl create nodegroup --cluster=test-node-az-1 --nodes=1 --region=eu-north-1 --node-zones=eu-north-1c -P
[ℹ]  using region eu-north-1
[ℹ]  nodegroup "ng-f7d7b06a" will use "ami-06ee67302ab7cf838" [AmazonLinux2/1.11]
[ℹ]  will create a Cloudformation stack for nodegroup ng-f7d7b06a in cluster test-node-az-1
[ℹ]  creating nodegroup stack "eksctl-test-node-az-1-nodegroup-ng-f7d7b06a"
[ℹ]  nodegroup "ng-f7d7b06a" has 0 node(s)
[ℹ]  waiting for at least 1 node(s) to become ready in "ng-f7d7b06a"

[ℹ]  nodegroup "ng-f7d7b06a" has 1 node(s)
[ℹ]  node "ip-192-168-139-140.eu-north-1.compute.internal" is ready
[✔]  created nodegroup "ng-f7d7b06a" in cluster "test-node-az-1"
[ℹ]  will inspect security group configuration for all nodegroups
 [0] >> kubectl get nodes -o wide
NAME                                             STATUS   ROLES    AGE   VERSION   INTERNAL-IP       EXTERNAL-IP     OS-IMAGE         KERNEL-VERSION               CONTAINER-RUNTIME
ip-192-168-139-140.eu-north-1.compute.internal   Ready    <none>   55s   v1.11.5   192.168.139.140   <none>          Amazon Linux 2   4.14.88-88.76.amzn2.x86_64   docker://17.6.2
ip-192-168-47-78.eu-north-1.compute.internal     Ready    <none>   6m    v1.11.5   192.168.47.78     13.53.171.172   Amazon Linux 2   4.14.88-88.76.amzn2.x86_64   docker://17.6.2
ip-192-168-94-149.eu-north-1.compute.internal    Ready    <none>   18m   v1.11.5   192.168.94.149    13.53.132.191   Amazon Linux 2   4.14.88-88.76.amzn2.x86_64   docker://17.6.2
 [0] >> kubectl get nodes -o wide -l failure-domain.beta.kubernetes.io/zone=eu-north-1c
NAME                                             STATUS   ROLES    AGE   VERSION   INTERNAL-IP       EXTERNAL-IP     OS-IMAGE         KERNEL-VERSION               CONTAINER-RUNTIME
ip-192-168-139-140.eu-north-1.compute.internal   Ready    <none>   1m    v1.11.5   192.168.139.140   <none>          Amazon Linux 2   4.14.88-88.76.amzn2.x86_64   docker://17.6.2
ip-192-168-47-78.eu-north-1.compute.internal     Ready    <none>   6m    v1.11.5   192.168.47.78     13.53.171.172   Amazon Linux 2   4.14.88-88.76.amzn2.x86_64   docker://17.6.2
 [0] >> kubectl get nodes -o wide -l failure-domain.beta.kubernetes.io/zone=eu-north-1c -l alpha.eksctl.io/nodegroup-name=ng-47ff879e 
NAME                                           STATUS   ROLES    AGE   VERSION   INTERNAL-IP     EXTERNAL-IP     OS-IMAGE         KERNEL-VERSION               CONTAINER-RUNTIME
ip-192-168-47-78.eu-north-1.compute.internal   Ready    <none>   7m    v1.11.5   192.168.47.78   13.53.171.172   Amazon Linux 2   4.14.88-88.76.amzn2.x86_64   docker://17.6.2
 [0] >> kubectl get nodes -o wide -l failure-domain.beta.kubernetes.io/zone=eu-north-1c -l alpha.eksctl.io/nodegroup-name=ng-f7d7b06a
NAME                                             STATUS   ROLES    AGE   VERSION   INTERNAL-IP       EXTERNAL-IP   OS-IMAGE         KERNEL-VERSION               CONTAINER-RUNTIME
ip-192-168-139-140.eu-north-1.compute.internal   Ready    <none>   2m    v1.11.5   192.168.139.140   <none>        Amazon Linux 2   4.14.88-88.76.amzn2.x86_64   docker://17.6.2
 [0] >> 

[dlespiau]

\o/

[errordeveloper]

thanks @dlespiau!