WIP: add first run at app rollback command

See coop-cloud/organising#146.

pkg/app/app.go

@@ -1,7 +1,13 @@
 package app
 
 import (
+	"context"
+	"fmt"
+	"strings"
+
+	"coopcloud.tech/abra/pkg/client/stack"
 	"coopcloud.tech/abra/pkg/config"
+	apiclient "github.com/docker/docker/client"
 )
 
 // Get retrieves an app
@@ -18,3 +24,45 @@ func Get(appName string) (config.App, error) {
 
 	return app, nil
 }
+
+// deployedServiceSpec represents a deployed service of an app.
+type deployedServiceSpec struct {
+	Name    string
+	Version string
+}
+
+// VersionSpec represents a deployed app and associated metadata.
+type VersionSpec map[string]deployedServiceSpec
+
+// DeployedVersions lists metadata (e.g. versions) for deployed
+func DeployedVersions(ctx context.Context, cl *apiclient.Client, app config.App) (VersionSpec, bool, error) {
+	services, err := stack.GetStackServices(ctx, cl, app.StackName())
+	if err != nil {
+		return VersionSpec{}, false, err
+	}
+
+	appSpec := make(VersionSpec)
+	for _, service := range services {
+		serviceName := ParseServiceName(service.Spec.Name)
+		label := fmt.Sprintf("coop-cloud.%s.%s.version", app.StackName(), serviceName)
+		if deployLabel, ok := service.Spec.Labels[label]; ok {
+			version, _ := ParseVersionLabel(deployLabel)
+			appSpec[serviceName] = deployedServiceSpec{Name: serviceName, Version: version}
+		}
+	}
+
+	return appSpec, len(services) > 0, nil
+}
+
+// ParseVersionLabel parses a $VERSION-$DIGEST app service label.
+func ParseVersionLabel(label string) (string, string) {
+	// versions may look like v4.2-abcd or v4.2-alpine-abcd
+	idx := strings.LastIndex(label, "-")
+	return label[:idx], label[idx+1:]
+}
+
+// ParseVersionName parses a $STACK_NAME_$SERVICE_NAME service label.
+func ParseServiceName(label string) string {
+	idx := strings.LastIndex(label, "_")
+	return label[idx+1:]
+}