feat: add cluster context support in Compose with x-context extension

cmd/uncloud/build.go

@@ -98,6 +98,8 @@ func runBuild(ctx context.Context, uncli *cli.CLI, opts buildOptions) error {
 		return fmt.Errorf("load compose file(s): %w", err)
 	}
 
+	uncli.SetClusterContextIfUnset(compose.ClusterContext(project))
+
 	servicesToBuild, err := cli.ServicesThatNeedBuild(project, opts.Services, opts.Deps)
 	if err != nil {
 		return fmt.Errorf("determine services to build: %w", err)

cmd/uncloud/deploy.go

@@ -83,6 +83,8 @@ func runDeploy(ctx context.Context, uncli *cli.CLI, opts deployOptions) error {
 		return fmt.Errorf("load compose file(s): %w", err)
 	}
 
+	uncli.SetClusterContextIfUnset(compose.ClusterContext(project))
+
 	if len(opts.services) > 0 {
 		// Includes service dependencies by default. This is the default docker compose behavior.
 		project, err = project.WithSelectedServices(opts.services)

cmd/uncloud/service/logs.go

@@ -107,6 +107,9 @@ func runLogs(ctx context.Context, uncli *cli.CLI, serviceNames []string, opts lo
 		if err != nil {
 			return fmt.Errorf("load Compose file(s): %w", err)
 		}
+
+		uncli.SetClusterContextIfUnset(compose.ClusterContext(project))
+
 		// View logs for all services, including disabled by inactive profiles.
 		serviceNames = append(project.ServiceNames(), project.DisabledServiceNames()...)
 		if len(serviceNames) == 0 {

internal/cli/cli.go

@@ -561,6 +561,15 @@ func provisionOrConnectRemoteMachine(
 	return machineClient, nil
 }
 
+// SetClusterContextIfUnset sets the cluster context override only if no --context flag was used
+// and no --connect direct connection is active.
+func (cli *CLI) SetClusterContextIfUnset(name string) {
+	if name == "" || cli.contextOverride != "" || cli.conn != nil {
+		return
+	}
+	cli.contextOverride = name
+}
+
 // ProgressOut returns an output stream for progress writer.
 func (cli *CLI) ProgressOut() *streams.Out {
 	return streams.NewOut(os.Stdout)

pkg/client/compose/context.go

@@ -0,0 +1,22 @@
+package compose
+
+import (
+	"github.com/compose-spec/compose-go/v2/types"
+)
+
+// ContextExtensionKey is the top-level Compose extension key for specifying the cluster context.
+const ContextExtensionKey = "x-context"
+
+// ClusterContext extracts the x-context value from the project's top-level extensions.
+// Returns an empty string if x-context is not set.
+func ClusterContext(project *types.Project) string {
+	v, ok := project.Extensions[ContextExtensionKey]
+	if !ok {
+		return ""
+	}
+	s, ok := v.(string)
+	if !ok {
+		return ""
+	}
+	return s
+}

pkg/client/compose/context_test.go

@@ -0,0 +1,45 @@
+package compose
+
+import (
+	"context"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestClusterContext(t *testing.T) {
+	tests := []struct {
+		name    string
+		content string
+		want    string
+	}{
+		{
+			name: "no x-context",
+			content: `
+services:
+  web:
+    image: nginx
+`,
+			want: "",
+		},
+		{
+			name: "x-context set",
+			content: `
+x-context: prod
+services:
+  web:
+    image: nginx
+`,
+			want: "prod",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			project, err := LoadProjectFromContent(context.Background(), tt.content)
+			require.NoError(t, err)
+			assert.Equal(t, tt.want, ClusterContext(project))
+		})
+	}
+}

website/docs/4-guides/1-deployments/1-deploy-app.md

@@ -322,6 +322,24 @@ Choose unique names to avoid conflicts with services deployed from other Compose
 
 :::
 
+## Deploy to a specific cluster context
+
+If you manage multiple clusters, you can set `x-context` in your Compose file to make sure it always deploys to the
+correct one. You won't need to remember to manually switch clusters with `uc ctx` or `--context`.
+
+```yaml title="compose.yaml"
+x-context: prod
+
+services:
+  web:
+    image: myapp:latest
+```
+
+With this configuration, `uc deploy` and other commands using the Compose file will always target the `prod` context,
+regardless of your currently active context. You can still override it with the `--context` flag if needed.
+
+See [`x-context`](../../8-compose-file-reference/1-support-matrix.md#x-context) for more details.
+
 ## Use a different Compose file location
 
 If your Compose file has a different name or location, use the `-f/--file` flag to specify its path:

website/docs/8-compose-file-reference/1-support-matrix.md

@@ -72,6 +72,7 @@ If you rely on a specific Compose feature that is not supported by Uncloud, plea
 | External configs    | ❌ Not supported    | Not supported                                                                                                  |
 | Short syntax        | ❌ Not supported    | Use long syntax only                                                                                           |
 | **Extensions**      |                    |                                                                                                                |
+| `x-context`         | ✅ Uncloud-specific | Cluster context override                                                                                       |
 | `x-caddy`           | ✅ Uncloud-specific | Custom Caddy configuration                                                                                     |
 | `x-machines`        | ✅ Uncloud-specific | Machine placement constraints                                                                                  |
 | `x-ports`           | ✅ Uncloud-specific | Service port publishing                                                                                        |
@@ -86,6 +87,25 @@ If you rely on a specific Compose feature that is not supported by Uncloud, plea
 
 Uncloud provides several custom extensions to enhance the Compose experience:
 
+### `x-context`
+
+Set the cluster context for all commands that use the Compose file, such as `deploy`, `build`, and `logs`. This is
+useful when you manage multiple clusters and want to make sure a Compose file is always deployed to the right one.
+No need to remember to manually switch clusters with `uc ctx` or `--context`.
+
+`x-context` is a top-level key, not a service-level attribute.
+
+```yaml
+x-context: prod
+
+services:
+  web:
+    image: nginx
+```
+
+The `--context` and `--connect` flags take precedence over `x-context`. If you don't specify any of these, the current
+context from your Uncloud config (`--uncloud-config`) is used.
+
 ### `x-ports`
 
 Expose HTTP/HTTPS service ports via the Caddy reverse proxy, or bind TCP/UDP ports directly to the host: