Add support for custom extraArgs to kine process

docs/configuration.md

@@ -142,6 +142,7 @@ spec:
 | `etcd.ca.expiresAfter`            | The expiration duration of the CA certificate (default: 87600h)                                                                                                        |
 | `etcd.ca.certificatesExpireAfter` | The expiration duration of the server certificate (default: 8760h)                                                                                                     |
 | `kine.dataSource`                 | [kine](https://github.com/k3s-io/kine) datasource URL.                                                                                                                 |
+| `kine.extraArgs`                  | Map of key-values (strings) for any extra arguments to pass down to kine process. Any behavior triggered by these parameters is outside k0s support.                   |
 | `etcd.externalCluster`            | Configuration when etcd is externally managed, i.e. running on dedicated nodes. See [`spec.storage.etcd.externalCluster`](#specstorageetcdexternalcluster)             |
 
 #### `spec.storage.etcd.externalCluster`

pkg/apis/k0s/v1beta1/storage.go

@@ -63,6 +63,9 @@ const (
 type KineConfig struct {
 	// kine datasource URL
 	DataSource string `json:"dataSource,omitempty"`
+
+	// Map of key-values (strings) for any extra arguments you want to pass down to the kine process
+	ExtraArgs map[string]string `json:"extraArgs,omitempty"`
 }
 
 // DefaultStorageSpec creates StorageSpec with sane defaults

pkg/apis/k0s/v1beta1/storage_test.go

@@ -74,6 +74,19 @@ func TestStorageSpec_IsJoinable(t *testing.T) {
 			},
 			want: true,
 		},
+		{
+			name: "kine-mysql-extra-args",
+			storage: StorageSpec{
+				Type: "kine",
+				Kine: &KineConfig{
+					DataSource: "mysql://foobar",
+					ExtraArgs: map[string]string{
+						"datastore-max-open-connections": "10",
+					},
+				},
+			},
+			want: true,
+		},
 		{
 			name: "kine-postgres",
 			storage: StorageSpec{

pkg/component/controller/kine.go

@@ -35,6 +35,7 @@ import (
 	"github.com/sirupsen/logrus"
 
 	"github.com/k0sproject/k0s/internal/pkg/dir"
+	"github.com/k0sproject/k0s/internal/pkg/stringmap"
 	"github.com/k0sproject/k0s/internal/pkg/users"
 	"github.com/k0sproject/k0s/pkg/assets"
 	"github.com/k0sproject/k0s/pkg/constant"
@@ -113,22 +114,33 @@ func (k *Kine) Init(_ context.Context) error {
 func (k *Kine) Start(ctx context.Context) error {
 	logrus.Info("Starting kine")
 
+	args := stringmap.StringMap{
+		"--endpoint": k.Config.DataSource,
+		// NB: kine doesn't parse URLs properly, so construct potentially
+		// invalid URLs that are understood by kine.
+		// https://github.com/k3s-io/kine/blob/v0.13.12/pkg/util/network.go#L5-L13
+		"--listen-address": "unix://" + k.K0sVars.KineSocketPath,
+		// Enable metrics on port 2380. The default is 8080, which clashes with kube-router.
+		"--metrics-bind-address": ":2380",
+	}
+
+	// Add custom flags from the config if provided via kine.extraArgs
+	for name, value := range k.Config.ExtraArgs {
+		argName := "--" + name
+		if _, ok := args[argName]; ok {
+			logrus.Warnf("overriding kine flag with user provided value: %s", argName)
+		}
+		args[argName] = value
+	}
+
 	k.supervisor = supervisor.Supervisor{
 		Name:    "kine",
 		BinPath: assets.BinPath("kine", k.K0sVars.BinDir),
 		DataDir: k.K0sVars.DataDir,
 		RunDir:  k.K0sVars.RunDir,
-		Args: []string{
-			"--endpoint=" + k.Config.DataSource,
-			// NB: kine doesn't parse URLs properly, so construct potentially
-			// invalid URLs that are understood by kine.
-			// https://github.com/k3s-io/kine/blob/v0.13.12/pkg/util/network.go#L5-L13
-			"--listen-address=unix://" + k.K0sVars.KineSocketPath,
-			// Enable metrics on port 2380. The default is 8080, which clashes with kube-router.
-			"--metrics-bind-address=:2380",
-		},
-		UID: k.uid,
-		GID: k.gid,
+		Args:    args.ToArgs(),
+		UID:     k.uid,
+		GID:     k.gid,
 	}
 
 	return k.supervisor.Supervise()