refactor: stack func to client, mv app to new file

Stack interaction is now under client.

App types and functions moved from env to app under config

client/stack.go

@@ -0,0 +1,36 @@
+package client
+
+import (
+	"context"
+	"strings"
+
+	"github.com/docker/docker/api/types"
+	"github.com/docker/docker/api/types/filters"
+	"github.com/docker/docker/api/types/swarm"
+)
+
+const StackNamespace = "com.docker.stack.namespace"
+
+type StackStatus struct {
+	Services []swarm.Service
+	Err      error
+}
+
+func QueryStackStatus(contextName string) StackStatus {
+	cl, err := NewClientWithContext(contextName)
+	if err != nil {
+		if strings.Contains(err.Error(), "does not exist") {
+			// No local context found, bail out gracefully
+			return StackStatus{[]swarm.Service{}, nil}
+		}
+		return StackStatus{[]swarm.Service{}, err}
+	}
+	ctx := context.Background()
+	filter := filters.NewArgs()
+	filter.Add("label", StackNamespace)
+	services, err := cl.ServiceList(ctx, types.ServiceListOptions{Filters: filter})
+	if err != nil {
+		return StackStatus{[]swarm.Service{}, err}
+	}
+	return StackStatus{services, nil}
+}