* Change the workers managed instance group to health check nodes
via HTTP probe of the kube-proxy port 10256 /healthz endpoints
* Advantages: kube-proxy is a lower value target (in case there
were bugs in firewalls) that Kubelet, its more representative than
health checking Kubelet (Kubelet must run AND kube-proxy Daemonset
must be healthy), and its already used by kube-proxy liveness probes
(better discoverability via kubectl or alerts on pods crashlooping)
* Another motivator is that GKE clusters also use kube-proxy port
10256 checks to assess node health
* Changes to worker launch configurations start an autoscaling group instance
refresh to replace instances
* Instance refresh creates surge instances, waits for a warm-up period, then
deletes old instances
* Changing worker_type, disk_*, worker_price, worker_target_groups, or Butane
worker_snippets on existing worker nodes will replace instances
* New AMIs or changing `os_stream` will be ignored, to allow Fedora CoreOS or
Flatcar Linux to keep themselves updated
* Previously, new launch configurations were made in the same way, but not
applied to instances unless manually replaced
* When a worker managed instance group's (MIG) instance template
changes (including machine type, disk size, or Butane snippets
but excluding new AMIs), use Google Cloud's rolling update features
to ensure instances match declared state
* Ignore new AMIs since Fedora CoreOS and Flatcar Linux nodes
already auto-update and reboot themselves
* Rolling updates will create surge instances, wait for health
checks, then delete old instances (0 unavilable instances)
* Instances are replaced to ensure new Ignition/Butane snippets
are respected
* Add managed instance group autohealing (i.e. health checks) to
ensure new instances' Kubelet is running
Renames
* Name apiserver and kubelet health checks consistently
* Rename MIG from `${var.name}-worker-group` to `${var.name}-worker`
Rel: https://cloud.google.com/compute/docs/instance-groups/rolling-out-updates-to-managed-instance-groups
* Rename launch configuration to use a name_prefix named after the
cluster and worker to improve identifiability
* Shorten AWS autoscaling group name to not include the launch config
id. Years ago this used to be needed to update the ASG but the AWS
provider detects changes to the launch configuration just fine
* Typhoon Fedora CoreOS is already using iptables nf_tables since
F36. The file to pin to legacy iptables was renamed to
/etc/coreos/iptables-legacy.stamp
* Requires poseidon v0.11+ and Flatcar Linux 3185.0.0+ (action required)
* Previously, Flatcar Linux configs have been parsed as Container
Linux Configs to Ignition v2.2.0 specs by poseidon/ct
* Flatcar Linux starting in 3185.0.0 now supports Ignition v3.x specs
(which are rendered from Butane Configs, like Fedora CoreOS)
* poseidon/ct v0.11.0 adds support for the flatcar Butane Config
variant so that Flatcar Linux can use Ignition v3.x
Rel:
* [Flatcar Support](https://flatcar-linux.org/docs/latest/provisioning/ignition/specification/#ignition-v3)
* [poseidon/ct support](https://github.com/poseidon/terraform-provider-ct/pull/131)
* Google Cloud Terraform provider resource google_dns_record_set's
name field provides the full domain name with a trailing ".". This
isn't a new behavior, Google has behaved this way as long as I can
remember
* etcd domain names are passed to the bootstrap module to generate
TLS certificates. What seems to be new(ish?) is that etcd peers
see example.foo and example.foo. as different domains during TLS
SANs validation. As a result, clusters with multiple controller
nodes fail to run etcd-member, which manifests as cluster provisioning
hanging. Single controller/master clusters (default) are unaffected
* Fix etcd-member.service error in multi-controller clusters:
```
"error":"x509: certificate is valid for conformance-etcd0.redacted.,
conform-etcd1.redacted., conform-etcd2.redacted., not conform-etcd1.redacted"}
```
* Fixes warning about use of deprecated field `key_algorithm` in
the `hashicorp/tls` provider. The key algorithm can now be inferred
directly from the private key so resources don't have to output
and pass around the algorithm
* Add `boot_disk[0].initialize_params` to the ignored fields for the
controller nodes
* Nodes will auto-update, Terraform should not attempt to delete and
recreate nodes (especially controllers!). Lack of this ignore causes
Terraform to propose deleting controller nodes when Flatcar Linux
releases new images
* Matches the configuration on Typhoon Fedora CoreOS (which does not
have the issue)
* Change subnet references to source and destinations prefixes
(plural)
* Remove references to a resource group in some load balancing
components, which no longer require it (inferred)
* Rename `worker_address_prefix` output to `worker_address_prefixes`
Dalton Hubble