feat: validate remaining unsupported items of the support-matrix (#429)

* feat: validate remaining unsupported items of the support-matrix

Validate unsupported compose features: external configs, container_name,
and placement.

This makes the code match the support-matrix as of now (added comment to
that effect as well).

Signed-off-by: Miek Gieben <miek@miek.nl>

* support matrix: some deploy modes are supported

Add tests for the various non-supported deploy modes.
Prefix the warnings with `deploy ` to signal the section, and to
differentiate between top level 'labels' and 'deploy labels'.

Signed-off-by: Miek Gieben <miek@miek.nl>

---------

Signed-off-by: Miek Gieben <miek@miek.nl>

pkg/client/compose/project_test.go

@@ -322,6 +322,79 @@ volumes:
 `,
 			shouldErr: true,
 		},
+		{
+			name: "external configs",
+			composeYAML: `services:
+  app:
+    image: myapp:latest
+configs:
+  http_config:
+    external: true
+`,
+			warnCount:    1,
+			warnContains: []string{"external"},
+		},
+		{
+			name: "container_name",
+			composeYAML: `services:
+  app:
+    image: myapp:latest
+    container_name: my_container
+`,
+			warnCount:    1,
+			warnContains: []string{"container_name"},
+		},
+		{
+			name: "deploy mode",
+			composeYAML: `services:
+  app:
+    image: myapp:latest
+    deploy:
+      mode: replicated-job
+      replicas: 2
+`,
+			warnCount:    1,
+			warnContains: []string{"deploy mode must"},
+		},
+		{
+			name: "deploy mode",
+			composeYAML: `services:
+  app:
+    image: myapp:latest
+    deploy:
+      mode: replicated
+      labels:
+        - foo
+      replicas: 2
+`,
+			warnCount:    1,
+			warnContains: []string{"deploy labels"},
+		},
+		{
+			name: "deploy restart_policy",
+			composeYAML: `services:
+  app:
+    image: myapp:latest
+    deploy:
+      restart_policy:
+        condition: on-failure
+`,
+			warnCount:    1,
+			warnContains: []string{"deploy restart_policy"},
+		},
+		{
+			name: "deploy placement",
+			composeYAML: `services:
+  app:
+    image: myapp:latest
+    deploy:
+      placement:
+        preferences:
+          - spread: foo
+`,
+			warnCount:    1,
+			warnContains: []string{"deploy placement"},
+		},
 	}
 
 	for _, tt := range tests {