Avoid using hardcoded value for max pod per node

[tanmng]

Right now in the user-data script we have

sed -i s,MAX_PODS,20,g /etc/systemd/system/kubelet.service

The value 20 is hardcoded right now. Since AWS released the numbers in their CloudFormation template, I think we can extract the value and use a lookup function to get the proper value.

A proposal:

locals {
  # Mapping from the node type that we selected and the max number of pods that it can run
  # Taken from https://amazon-eks.s3-us-west-2.amazonaws.com/1.10.3/2018-06-05/amazon-eks-nodegroup.yaml
  max_pod_per_node = {
    c4.large    = 29
    c4.xlarge   = 58
    c4.2xlarge  = 58
    c4.4xlarge  = 234
    c4.8xlarge  = 234
    c5.large    = 29
    c5.xlarge   = 58
    c5.2xlarge  = 58
    c5.4xlarge  = 234
    c5.9xlarge  = 234
    c5.18xlarge = 737
    i3.large    = 29
    i3.xlarge   = 58
    i3.2xlarge  = 58
    i3.4xlarge  = 234
    i3.8xlarge  = 234
    i3.16xlarge = 737
    m3.medium   = 12
    m3.large    = 29
    m3.xlarge   = 58
    m3.2xlarge  = 118
    m4.large    = 20
    m4.xlarge   = 58
    m4.2xlarge  = 58
    m4.4xlarge  = 234
    m4.10xlarge = 234
    m5.large    = 29
    m5.xlarge   = 58
    m5.2xlarge  = 58
    m5.4xlarge  = 234
    m5.12xlarge = 234
    m5.24xlarge = 737
    p2.xlarge   = 58
    p2.8xlarge  = 234
    p2.16xlarge = 234
    p3.2xlarge  = 58
    p3.8xlarge  = 234
    p3.16xlarge = 234
    r3.xlarge   = 58
    r3.2xlarge  = 58
    r3.4xlarge  = 234
    r3.8xlarge  = 234
    r4.large    = 29
    r4.xlarge   = 58
    r4.2xlarge  = 58
    r4.4xlarge  = 234
    r4.8xlarge  = 234
    r4.16xlarge = 737
    t2.small    = 8
    t2.medium   = 17
    t2.large    = 35
    t2.xlarge   = 44
    t2.2xlarge  = 44
    x1.16xlarge = 234
    x1.32xlarge = 234
  }

  workers_userdata = <<USERDATA
#!/bin/bash -xe
CA_CERTIFICATE_DIRECTORY=/etc/kubernetes/pki
CA_CERTIFICATE_FILE_PATH=$CA_CERTIFICATE_DIRECTORY/ca.crt
mkdir -p $CA_CERTIFICATE_DIRECTORY
echo "${aws_eks_cluster.this.certificate_authority.0.data}" | base64 -d >  $CA_CERTIFICATE_FILE_PATH
INTERNAL_IP=$(curl -s http://169.254.169.254/latest/meta-data/local-ipv4)
sed -i s,MASTER_ENDPOINT,${aws_eks_cluster.this.endpoint},g /var/lib/kubelet/kubeconfig
sed -i s,CLUSTER_NAME,${var.cluster_name},g /var/lib/kubelet/kubeconfig
sed -i s,REGION,${data.aws_region.current.name},g /etc/systemd/system/kubelet.service
sed -i s,MAX_PODS,${lookup(local.max_pod_per_node, var. workers_instance_type)},g /etc/systemd/system/kubelet.service
sed -i s,MASTER_ENDPOINT,${aws_eks_cluster.this.endpoint},g /etc/systemd/system/kubelet.service
sed -i s,INTERNAL_IP,$INTERNAL_IP,g /etc/systemd/system/kubelet.service
DNS_CLUSTER_IP=10.100.0.10
if [[ $INTERNAL_IP == 10.* ]] ; then DNS_CLUSTER_IP=172.20.0.10; fi
sed -i s,DNS_CLUSTER_IP,$DNS_CLUSTER_IP,g /etc/systemd/system/kubelet.service
sed -i s,CERTIFICATE_AUTHORITY_FILE,$CA_CERTIFICATE_FILE_PATH,g /var/lib/kubelet/kubeconfig
sed -i s,CLIENT_CA_FILE,$CA_CERTIFICATE_FILE_PATH,g  /etc/systemd/system/kubelet.service
systemctl daemon-reload
systemctl restart kubelet kube-proxy
USERDATA
}

@brandoconnor Please let me know if this is OK, I'll create a fork and a pull request later

[brandonjbjelland]

Hey @tanmng ,

Thanks and good catch! Absolutely follow through with a PR (in the way you've suggested) when you have a chance. Admittedly, I hadn't gone through the userdata script with a fine-tooth comb just yet. I'll keep an eye out for your PR and cut the first release of the project once these low-hanging bugs are wrapped up. 👍

[brandonjbjelland]

Thanks again! I shipped this change just now and am in the midst of releasing 0.1.0.

[antonbabenko]

@brandoconnor Great work with starting EKS module!

[tanmng]

@brandoconnor sorry it was a bit late so I didn't catch your message earlier.

I'm opening several PRs right now. Most of the content are taken from my hack last night

Cheers,

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