Fix Typhoon CI stage + add support for K8s 1.20

[alexsomesan]

Description

Recently the Fedora CoreOS node image used by the Typhoon k8s distro has strengthened their SSH policy to restrict RSA keys from being accepted. This causes the remote-exec provisioner in Terraform to fail to connect to such nodes and thus fail to properly provision the cluster. The reason for the failure is that the provisioner is using the crypto facilities built into Go which don't yet support the types of keys required by the new Fedora.

Detailed explanation here: poseidon/typhoon#915

To work around this, we switch to using flatcar Linux (an open-source CoreOS derivative) as the base OS image for the clusters.
Also, we have to drop support for Typhoon 1.18 as it doesn't have an option for Flatcar, only container Linux which has been discontinued and no longer working.

The change should be transparent from the point of view of Kubernetes clients.

Acceptance tests

Output from acceptance testing:

module.typhoon-acc-1_20[0].null_resource.bootstrap: Provisioning with 'remote-exec'...
module.typhoon-acc-1_20[0].null_resource.bootstrap (remote-exec): Connecting to remote host via SSH...
module.typhoon-acc-1_20[0].null_resource.bootstrap (remote-exec):   Host: 35.158.210.240
module.typhoon-acc-1_20[0].null_resource.bootstrap (remote-exec):   User: core
module.typhoon-acc-1_20[0].null_resource.bootstrap (remote-exec):   Password: false
module.typhoon-acc-1_20[0].null_resource.bootstrap (remote-exec):   Private key: false
module.typhoon-acc-1_20[0].null_resource.bootstrap (remote-exec):   Certificate: false
module.typhoon-acc-1_20[0].null_resource.bootstrap (remote-exec):   SSH Agent: true
module.typhoon-acc-1_20[0].null_resource.bootstrap (remote-exec):   Checking Host Key: false
module.typhoon-acc-1_20[0].null_resource.bootstrap (remote-exec): Connected!
module.typhoon-acc-1_20[0].null_resource.bootstrap: Still creating... [10s elapsed]
module.typhoon-acc-1_20[0].null_resource.bootstrap: Still creating... [20s elapsed]
module.typhoon-acc-1_20[0].null_resource.bootstrap: Still creating... [30s elapsed]
module.typhoon-acc-1_20[0].null_resource.bootstrap: Still creating... [40s elapsed]
module.typhoon-acc-1_20[0].null_resource.bootstrap: Still creating... [50s elapsed]
module.typhoon-acc-1_20[0].null_resource.bootstrap: Still creating... [1m0s elapsed]
module.typhoon-acc-1_20[0].null_resource.bootstrap: Still creating... [1m10s elapsed]
module.typhoon-acc-1_20[0].null_resource.bootstrap: Still creating... [1m20s elapsed]
module.typhoon-acc-1_20[0].null_resource.bootstrap: Still creating... [1m30s elapsed]
module.typhoon-acc-1_20[0].null_resource.bootstrap: Still creating... [1m40s elapsed]
module.typhoon-acc-1_20[0].null_resource.bootstrap: Still creating... [1m50s elapsed]
module.typhoon-acc-1_20[0].null_resource.bootstrap: Still creating... [2m0s elapsed]
module.typhoon-acc-1_20[0].null_resource.bootstrap: Still creating... [2m10s elapsed]
module.typhoon-acc-1_20[0].null_resource.bootstrap: Still creating... [2m20s elapsed]
module.typhoon-acc-1_20[0].null_resource.bootstrap: Still creating... [2m30s elapsed]
module.typhoon-acc-1_20[0].null_resource.bootstrap: Still creating... [2m40s elapsed]
module.typhoon-acc-1_20[0].null_resource.bootstrap: Still creating... [2m50s elapsed]
module.typhoon-acc-1_20[0].null_resource.bootstrap: Still creating... [3m0s elapsed]
module.typhoon-acc-1_20[0].null_resource.bootstrap: Creation complete after 3m1s [id=3782622098792055774]

Apply complete! Resources: 93 added, 0 changed, 0 destroyed.

Outputs:

kubeconfig_path = ./kubeconfig
workstation-arch% kubectl --kubeconfig kubeconfig get nodes -owide
NAME            STATUS     ROLES    AGE   VERSION   INTERNAL-IP   EXTERNAL-IP   OS-IMAGE                                              KERNEL-VERSION   CONTAINER-RUNTIME
ip-10-0-30-79   NotReady   <none>   0s    v1.20.2   10.0.30.79    <none>        Flatcar Container Linux by Kinvolk 2605.12.0 (Oklo)   5.4.92-flatcar   docker://19.3.14



...

Release Note

Release note for CHANGELOG:

N/A

References

Community Note

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[dak1n1]

Thanks for the fix!

[ghost]

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