feat: support PID namespace mode in Compose (#276)

This adds `pid: host` compose key support.

Modelled after #238.

See: #237

Signed-off-by: Miek Gieben <miek@miek.nl>
Co-authored-by: Pasha Sviderski <me@psviderski.name>

pkg/client/compose/service.go

@@ -53,6 +53,7 @@ func ServiceSpecFromCompose(project *types.Project, serviceName string) (api.Ser
 			Healthcheck: healthcheckFromCompose(service.HealthCheck),
 			Image:       service.Image,
 			Init:        service.Init,
+			Pid:         container.PidMode(service.Pid),
 			Privileged:  service.Privileged,
 			PullPolicy:  pullPolicy,
 			Resources:   resourcesFromCompose(service),

pkg/client/compose/service_test.go

@@ -127,6 +127,7 @@ func TestServiceSpecFromCompose(t *testing.T) {
 								"max-file": "3",
 							},
 						},
+						Pid:        "host",
 						Privileged: true,
 						PullPolicy: api.PullPolicyAlways,
 						Resources: api.ContainerResources{

pkg/client/compose/testdata/compose-full-spec.yaml

@@ -6,6 +6,7 @@ services:
       - ALL
     command: ["nginx", "updated", "command"]
     cpus: 0.5
+    pid: host
     deploy:
       update_config:
         order: stop-first