improvement: update the wait_for_cluster_cmd logic to use curl if wget doesn't exist

[daroga0002]

PR o'clock

Description

This PR is addressing issue related to wait_for_cluster_cmd check which is defaulting to wget. This is brining error if you missing wget on local system where you execute Terraform apply. This can be customized via wait_for_cluster_cmd but usually people are not following this and meet issue. In past there was few issues opened for this:

#998
#829

This PR is changing default wait_for_cluster_cmd to contain conditional which is checking wget availability, if this is missing then switch to curl. This logic should remediate most of issues which users meet (as wget is available on most linux distrubution and containers, where curl is available out of box in Mac OS).

I have tested module on my Mac OS with wget available, then repeated test with unavailable wget and available curl:

Execution with wget available:

$ terraform apply
.......................
module.eks.aws_eks_cluster.this[0]: Still creating... [9m40s elapsed]
module.eks.aws_eks_cluster.this[0]: Creation complete after 9m44s [id=test-eks-irsa]
module.eks.null_resource.wait_for_cluster[0]: Creating...
module.eks.aws_iam_openid_connect_provider.oidc_provider[0]: Creating...
module.eks.aws_iam_role.workers[0]: Creating...
module.eks.data.template_file.userdata[0]: Refreshing state...
module.eks.null_resource.wait_for_cluster[0]: Provisioning with 'local-exec'...
module.iam_assumable_role_admin.data.aws_iam_policy_document.assume_role_with_oidc[0]: Refreshing state...
module.eks.null_resource.wait_for_cluster[0] (local-exec): Executing: ["/bin/sh" "-c" "for i in `seq 1 60`; do if `command -v wget > /dev/null`; then wget --no-check-certificate -O - -q $ENDPOINT/healthz >/dev/null && exit 0 || true; else curl -k -s $ENDPOINT/healthz >/dev/null && exit 0 || true;fi; sleep 5; done; echo TIMEOUT && exit 1"]
module.eks.local_file.kubeconfig[0]: Creating...
.......................
module.iam_assumable_role_admin.aws_iam_role_policy_attachment.custom[0]: Creation complete after 2s [id=cluster-autoscaler-2020090709290497280000000f]

Apply complete! Resources: 38 added, 0 changed, 0 destroyed.
.......................

Removed wget

$ command -v wget
$ command -v curl 
/usr/bin/curl
$ 

Execution with wget unavailable:

$ terraform apply
.......................
module.eks.aws_eks_cluster.this[0]: Still creating... [13m0s elapsed]
module.eks.aws_eks_cluster.this[0]: Creation complete after 13m5s [id=test-eks-irsa]
module.eks.null_resource.wait_for_cluster[0]: Creating...
module.iam_assumable_role_admin.data.aws_iam_policy_document.assume_role_with_oidc[0]: Refreshing state...
module.eks.aws_iam_openid_connect_provider.oidc_provider[0]: Creating...
module.eks.aws_iam_role.workers[0]: Creating...
module.eks.data.template_file.userdata[0]: Refreshing state...
module.eks.null_resource.wait_for_cluster[0]: Provisioning with 'local-exec'...
module.eks.null_resource.wait_for_cluster[0] (local-exec): Executing: ["/bin/sh" "-c" "for i in `seq 1 60`; do if `command -v wget > /dev/null`; then wget --no-check-certificate -O - -q $ENDPOINT/healthz >/dev/null && exit 0 || true; else curl -k -s $ENDPOINT/healthz >/dev/null && exit 0 || true;fi; sleep 5; done; echo TIMEOUT && exit 1"]
module.eks.local_file.kubeconfig[0]: Creating...
module.eks.local_file.kubeconfig[0]: Creation complete after 0s [id=73dcc2465e8a560fe68b82dfd8aa20d4160e6d73]
.......................
module.iam_assumable_role_admin.aws_iam_role_policy_attachment.custom[0]: Creation complete after 2s [id=cluster-autoscaler-2020090709555407010000000f]

Apply complete! Resources: 38 added, 0 changed, 0 destroyed.
.......................

Checklist

• CI tests are passing
• README.md has been updated after any changes to variables and outputs. See https://github.com/terraform-aws-modules/terraform-aws-eks/#doc-generation

[random930]

Great idea! Looks good to me.

[barryib]

Thanks @daroga0002 for your contribution, can you please rebase your branch master to resolve conflict so I can merge your PR in ?

[barryib]

Thanks @daroga0002 for your contribution.

[github-actions]

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