Convert Depreacted Flags for v1.26

[dereknola]

Component of #5940, with v1.26, we need to completely remove the following flags from k3s and docs.

• no-flannel
• cluster-secret
• no-deploy
• disable-selinux

Additionally, the following need to convert to fatal errors:

• wireguard backend
• k3s etcd-snapshot will no longer save a snapshot

[manuelbuil]

@rbrtbnfgl and I need to also remove wireguard backend which was marked as deprecated for some time now. Maybe we can track it in this issue too? Or better create a new one?

[bguzman-3pillar]

Validated on b5d39df

Environment Details

Infrastructure

• Cloud
• Hosted

Cluster Configuration:

1 server

Testing Steps

1. Try to install K3S using these flags: no-flannel, cluster-secret, no-deploy, disable-selinux.
2. Ensure that k3s complains about a nonexistent flag.
3. etcd-snapshot-> Install K3S, deploy some workloads, run k3s etcd-snapshot

Validation Results:

curl -sfL https://get.k3s.io | INSTALL_K3S_COMMIT=b5d39df9294627cbfa3081acb92e2be54f02b0d6 INSTALL_K3S_EXEC="server --no-flannel" sh -

$ journalctl -xeu k3s.service | grep -i "fatal msg"
Dec 09 20:19:02 ip-172-31-33-97 k3s[3083]: time="2022-12-09T20:19:02Z" level=fatal msg="flag provided but not defined: -no-flannel"
Dec 09 20:19:08 ip-172-31-33-97 k3s[3092]: time="2022-12-09T20:19:07Z" level=fatal msg="flag provided but not defined: -no-flannel"

$ curl -sfL https://get.k3s.io | INSTALL_K3S_COMMIT=b5d39df9294627cbfa3081acb92e2be54f02b0d6 INSTALL_K3S_EXEC="server --no-deploy coredns" sh -

$ journalctl -xeu k3s.service | grep -i "fatal msg"
Dec 09 20:29:55 ip-172-31-33-97 k3s[7444]: time="2022-12-09T20:29:55Z" level=fatal msg="flag provided but not defined: -no-deploy"
Dec 09 20:30:00 ip-172-31-33-97 k3s[7453]: time="2022-12-09T20:30:00Z" level=fatal msg="flag provided but not defined: -no-deploy"

curl -sfL https://get.k3s.io | INSTALL_K3S_COMMIT=b5d39df9294627cbfa3081acb92e2be54f02b0d6 INSTALL_K3S_EXEC="server --disable-selinux" sh -

$ journalctl -xeu k3s.service | grep -i "fatal"
Dec 09 20:32:00 ip-172-31-33-97 k3s[7945]: time="2022-12-09T20:32:00Z" level=fatal msg="flag provided but not defined: -disable-selinux"
Dec 09 20:32:05 ip-172-31-33-97 k3s[7955]: time="2022-12-09T20:32:05Z" level=fatal msg="flag provided but not defined: -disable-selinux"

$ curl -sfL https://get.k3s.io | INSTALL_K3S_COMMIT=b5d39df9294627cbfa3081acb92e2be54f02b0d6 INSTALL_K3S_EXEC="server --cluster-secret secret" sh -

$ journalctl -xeu k3s.service | grep -i "fatal"
Dec 09 20:35:13 ip-172-31-33-97 k3s[8541]: time="2022-12-09T20:35:13Z" level=fatal msg="flag provided but not defined: -cluster-secret"
Dec 09 20:35:18 ip-172-31-33-97 k3s[8549]: time="2022-12-09T20:35:18Z" level=fatal msg="flag provided but not defined: -cluster-secret"

• Etcd-snapshot

$ curl -sfL https://get.k3s.io | INSTALL_K3S_COMMIT=b5d39df9294627cbfa3081acb92e2be54f02b0d6 INSTALL_K3S_EXEC="server --cluster-init" sh -

$ sudo k3s etcd-snapshot
NAME:
   k3s etcd-snapshot - Trigger an immediate etcd snapshot

USAGE:
   k3s etcd-snapshot [global options] command [command options] [arguments...]

VERSION:
   v1.25.4+k3s-b5d39df9 (b5d39df9)

COMMANDS:
   delete       Delete given snapshot(s)
   ls, list, l  List snapshots
   prune        Remove snapshots that match the name prefix that exceed the configured retention count
   save         Trigger an immediate etcd snapshot

GLOBAL OPTIONS:
   --debug                                              (logging) Turn on debug logs [$K3S_DEBUG]
   --config FILE, -c FILE                               (config) Load configuration from FILE (default: "/etc/rancher/k3s/config.yaml") [$K3S_CONFIG_FILE]
   --log value, -l value                                (logging) Log to file
   --alsologtostderr                                    (logging) Log to standard error as well as file (if set)
   --node-name value                                    (agent/node) Node name [$K3S_NODE_NAME]
   --data-dir value, -d value                           (data) Folder to hold state default /var/lib/rancher/k3s or ${HOME}/.rancher/k3s if not root
   --dir value, --etcd-snapshot-dir value               (db) Directory to save etcd on-demand snapshot. (default: ${data-dir}/db/snapshots)
   --name value                                         (db) Set the base name of the etcd on-demand snapshot (appended with UNIX timestamp). (default: "on-demand")
   --snapshot-compress, --etcd-snapshot-compress        (db) Compress etcd snapshot
   --s3, --etcd-s3                                      (db) Enable backup to S3
   --s3-endpoint value, --etcd-s3-endpoint value        (db) S3 endpoint url (default: "s3.amazonaws.com")
   --s3-endpoint-ca value, --etcd-s3-endpoint-ca value  (db) S3 custom CA cert to connect to S3 endpoint
   --s3-skip-ssl-verify, --etcd-s3-skip-ssl-verify      (db) Disables S3 SSL certificate validation
   --s3-access-key value, --etcd-s3-access-key value    (db) S3 access key [$AWS_ACCESS_KEY_ID]
   --s3-secret-key value, --etcd-s3-secret-key value    (db) S3 secret key [$AWS_SECRET_ACCESS_KEY]
   --s3-bucket value, --etcd-s3-bucket value            (db) S3 bucket name
   --s3-region value, --etcd-s3-region value            (db) S3 region / bucket location (optional) (default: "us-east-1")
   --s3-folder value, --etcd-s3-folder value            (db) S3 folder
   --s3-insecure, --etcd-s3-insecure                    (db) Disables S3 over HTTPS
   --s3-timeout value, --etcd-s3-timeout value          (db) S3 timeout (default: 5m0s)
   --help, -h                                           show help
FATA[0000] saving with etcd-snapshot was deprecated in v1.26, use "etcd-snapshot save" instead 

• Wireguard

curl -sfL https://get.k3s.io | INSTALL_K3S_COMMIT=b5d39df9294627cbfa3081acb92e2be54f02b0d6 INSTALL_K3S_EXEC="server --flannel-backend wireguard" sh -

$ journalctl -xeu k3s.service | grep -i "fatal"
Dec 09 20:54:37 ip-172-31-33-97 k3s[16918]: time="2022-12-09T20:54:37Z" level=fatal msg="The wireguard backend was deprecated in K3s v1.26, please switch to wireguard-native. Check our docs at docs.k3s.io/installation/network-options for information about how to migrate."
Dec 09 20:54:42 ip-172-31-33-97 k3s[16937]: time="2022-12-09T20:54:42Z" level=fatal msg="The wireguard backend was deprecated in K3s v1.26, please switch to wireguard-native. Check our docs at docs.k3s.io/installation/network-options for information about how to migrate."

Additional context / logs: