feat: add the ability to create k3s node profiles

Node profiles can be used to specify repetitive options for clusters, making it easier to add specific types of instances quickly.

This PR additionally fixes kubelet-args specification - the same key can be specified multiple times, such as when specifying custom sysctl rules.

docs/deployment/schedulers/k3s.md

@@ -12,7 +12,10 @@ scheduler-k3s:cluster-list                          # Lists all nodes in a Dokku
 scheduler-k3s:cluster-remove [node-id]              # Removes client node to a Dokku-managed cluster
 scheduler-k3s:ensure-charts                         # Ensures the k3s charts are installed
 scheduler-k3s:initialize                            # Initializes a cluster
-scheduler-k3s:labels:set <app|--global> <property> (<value>) [--process-type PROCESS_TYPE] <--resource-type RESOURCE_TYPE>, Set or clear a label for a given app/process-type/resource-type combination
+scheduler-k3s:labels:set <app|--global> <property> (<value>) [--process-type PROCESS_TYPE] <--resource-type RESOURCE_TYPE> # Set or clear a label for a given app/process-type/resource-type combination
+scheduler-k3s:profiles:add <profile> [--role ROLE] [--insecure-allow-unknown-hosts] [--taint-scheduling] [--kubelet-args KUBELET_ARGS] Adds a node profile to the k3s cluster
+scheduler-k3s:profiles:list [--format json|stdout]  # Lists all node profiles in the k3s cluster
+scheduler-k3s:profiles:remove <profile>             # Removes a node profile from the k3s cluster
 scheduler-k3s:report [<app>] [<flag>]               # Displays a scheduler-k3s report for one or more apps
 scheduler-k3s:set [<app>|--global] <key> (<value>)  # Set or clear a scheduler-k3s property for an app or the scheduler
 scheduler-k3s:show-kubeconfig                       # Displays the kubeconfig for remote usage
@@ -83,6 +86,22 @@ Nodes that run app workloads can be added via the `scheduler-k3s:cluster-add` co
 dokku scheduler-k3s:cluster-add  ssh://root@worker-1.example.com
 ```
 
+Per-node kubelet flags can be supplied by passing `--kubelet-args` with a comma-separated `key=value` list. This is useful for tuning scheduler capacity or enforcing cluster-wide defaults at the node level.
+
+```shell
+dokku scheduler-k3s:cluster-add \
+  --kubelet-args allowed-unsafe-sysctls=net.ipv6.conf.all.disable_ipv6 \
+  ssh://root@worker-1.example.com
+```
+
+Multiple kubelet arguments can be specified in the same call by separating them with commas. The following example enables IPv4 forwarding while also increasing the pod density on the worker.
+
+```shell
+dokku scheduler-k3s:cluster-add \
+  --kubelet-args allowed-unsafe-sysctls=net.ipv6.conf.all.disable_ipv6,max-pods=150 \
+  ssh://root@worker-2.example.com
+```
+
 If the server isn't in the `known_hosts` file, the connection will fail. This can be bypassed by setting the `--insecure-allow-unknown-hosts` flag:
 
 ```shell
@@ -134,6 +153,48 @@ When attaching an worker or server node, the K3s plugin will look at the IP asso
 dokku scheduler-k3s:set --global network-interface eth1
 ```
 
+### Node Profiles
+
+Node profiles capture repeatable `scheduler-k3s:cluster-add` options so you can join multiple nodes with identical settings. A profile name can be specified for the `scheduler-k3s:cluster-add` command via the  `--profile <name>` flag. Any flags passed directly to `scheduler-k3s:cluster-add` override the stored values for that run.
+
+#### Listing profiles
+
+Display stored profiles to understand which roles and behaviors will be used.
+
+```shell
+dokku scheduler-k3s:profiles:list
+```
+
+```
+name            role
+awesome-profile worker
+```
+
+This command also takes an optional `--format` flag to specify a format for the output. Options include `json` and `stdout`
+
+#### Adding profiles
+
+Create or update a profile that defines how new nodes should be prepared before joining the cluster.
+
+```shell
+dokku scheduler-k3s:profiles:add edge-workers \
+  --role worker \
+  --insecure-allow-unknown-hosts \
+  --kubelet-args protect-kernel-defaults=true,eviction-hard=memory.available<200Mi
+```
+
+Profile names must be alphanumeric, may include internal dashes, cannot start/end with a dash, and must be ≤32 characters. Other than the `--server-ip` flag, all flags used for `scheduler-k3s:cluster-add` are valid for the `scheduler-k3s:profiles:add` command.
+
+#### scheduler-k3s:profiles:remove
+
+Delete a profile once it’s no longer required.
+
+```shell
+dokku scheduler-k3s:profiles:remove edge-workers
+```
+
+Removal only deletes the stored definition; nodes that already joined the cluster keep their existing configuration.
+
 ### Changing deployment settings
 
 The k3s plugin provides a number of settings that can be used to managed deployments on a per-app basis. The following table outlines ones not covered elsewhere: