feat: add support for sysctls compose key (#239)

* feat: add support for `sysctls` compose key

* lint

---------

Co-authored-by: Pasha Sviderski <me@psviderski.name>

pkg/api/service.go

@@ -247,6 +247,8 @@ type ContainerSpec struct {
 	PullPolicy string
 	// Resource allocation for the container.
 	Resources ContainerResources
+	// Namespaced kernel parameters to be set in container
+	Sysctls map[string]string
 	// User overrides the default user of the image used to run the container. Format: user|UID[:group|GID].
 	User string
 	// VolumeMounts specifies how volumes are mounted into the container filesystem.
@@ -312,6 +314,14 @@ func (s *ContainerSpec) Equals(spec ContainerSpec) bool {
 func (s *ContainerSpec) Clone() ContainerSpec {
 	spec := *s
 
+	if s.CapAdd != nil {
+		spec.CapAdd = make([]string, len(s.CapAdd))
+		copy(spec.CapAdd, s.CapAdd)
+	}
+	if s.CapDrop != nil {
+		spec.CapDrop = make([]string, len(s.CapDrop))
+		copy(spec.CapDrop, s.CapDrop)
+	}
 	if s.Command != nil {
 		spec.Command = make([]string, len(s.Command))
 		copy(spec.Command, s.Command)
@@ -347,15 +357,12 @@ func (s *ContainerSpec) Clone() ContainerSpec {
 			spec.ConfigMounts[i] = cm.Clone()
 		}
 	}
-	if s.CapAdd != nil {
-		spec.CapAdd = make([]string, len(s.CapAdd))
-		copy(spec.CapAdd, s.CapAdd)
+	if s.Sysctls != nil {
+		spec.Sysctls = make(map[string]string, len(s.Sysctls))
+		for k, v := range s.Sysctls {
+			spec.Sysctls[k] = v
+		}
 	}
-	if s.CapDrop != nil {
-		spec.CapDrop = make([]string, len(s.CapDrop))
-		copy(spec.CapDrop, s.CapDrop)
-	}
-
 	return spec
 }