feat: add dynamic parameters websocket endpoint (#17165)

provisioner/echo/serve.go

@@ -211,6 +211,8 @@ type Responses struct {
 	// transition responses. They are prioritized over the generic responses.
 	ProvisionApplyMap map[proto.WorkspaceTransition][]*proto.Response
 	ProvisionPlanMap  map[proto.WorkspaceTransition][]*proto.Response
+
+	ExtraFiles map[string][]byte
 }
 
 // Tar returns a tar archive of responses to provisioner operations.
@@ -226,8 +228,12 @@ func TarWithOptions(ctx context.Context, logger slog.Logger, responses *Response
 
 	if responses == nil {
 		responses = &Responses{
-			ParseComplete, ApplyComplete, PlanComplete,
-			nil, nil,
+			Parse:             ParseComplete,
+			ProvisionApply:    ApplyComplete,
+			ProvisionPlan:     PlanComplete,
+			ProvisionApplyMap: nil,
+			ProvisionPlanMap:  nil,
+			ExtraFiles:        nil,
 		}
 	}
 	if responses.ProvisionPlan == nil {
@@ -327,6 +333,25 @@ func TarWithOptions(ctx context.Context, logger slog.Logger, responses *Response
 			}
 		}
 	}
+	for name, content := range responses.ExtraFiles {
+		logger.Debug(ctx, "extra file", slog.F("name", name))
+
+		err := writer.WriteHeader(&tar.Header{
+			Name: name,
+			Size: int64(len(content)),
+			Mode: 0o644,
+		})
+		if err != nil {
+			return nil, err
+		}
+
+		n, err := writer.Write(content)
+		if err != nil {
+			return nil, err
+		}
+
+		logger.Debug(context.Background(), "extra file written", slog.F("name", name), slog.F("bytes_written", n))
+	}
 	// `writer.Close()` function flushes the writer buffer, and adds extra padding to create a legal tarball.
 	err := writer.Close()
 	if err != nil {
@@ -347,3 +372,12 @@ func WithResources(resources []*proto.Resource) *Responses {
 		}}}},
 	}
 }
+
+func WithExtraFiles(extraFiles map[string][]byte) *Responses {
+	return &Responses{
+		Parse:          ParseComplete,
+		ProvisionApply: ApplyComplete,
+		ProvisionPlan:  PlanComplete,
+		ExtraFiles:     extraFiles,
+	}
+}