Allow selecting enabled worker languages (#309)

Author: mxschmitt

CONTRIBUTING.md

@@ -45,6 +45,9 @@ The control microservice is the server that receives requests from the user. It
 ### Worker
 
 For each of the languages, there are individual Docker images and worker implementations since each language gets executed differently.
+The control service enables all supported languages by default. Set the
+comma-separated `WORKER_LANGUAGES` environment variable before generating the
+Kubernetes manifests to run only a subset, for example `javascript,python`.
 
 ## Generate / Update autocompletion
 

control-service/main.go

@@ -104,8 +104,12 @@ func newServer() (*server, error) {
 		}
 	}
 
+	workerLanguages, err := parseWorkerLanguages(os.Getenv("WORKER_LANGUAGES"))
+	if err != nil {
+		return nil, err
+	}
 	workersMap := map[workertypes.WorkerLanguage]*Workers{}
-	for _, lang := range workertypes.SUPPORTED_LANGUAGES {
+	for _, lang := range workerLanguages {
 		workersMap[lang], err = newWorkers(lang, workerCount, k8ClientSet, amqpChannel)
 		if err != nil {
 			return nil, fmt.Errorf("could not create new %s workers: %w", lang, err)
@@ -186,6 +190,10 @@ func (s *server) handleRun(c *echo.Context) error {
 	if !req.Language.IsValid() {
 		return respondError(c, http.StatusBadRequest, requestID, testID, logBuffer, "could not recognize language")
 	}
+	workers, enabled := s.workers[req.Language]
+	if !enabled {
+		return respondError(c, http.StatusBadRequest, requestID, testID, logBuffer, "language is not enabled")
+	}
 
 	logger.Printf("Validating turnstile")
 	if err := ValidateTurnstile(c.Request().Context(), req.Token, getTurnstileIP(c), os.Getenv("TURNSTILE_SECRET_KEY")); err != nil {
@@ -197,7 +205,7 @@ func (s *server) handleRun(c *echo.Context) error {
 	logger.Printf("Obtaining worker")
 	var worker *Worker
 	select {
-	case worker = <-s.workers[req.Language].GetCh():
+	case worker = <-workers.GetCh():
 	case <-time.After(WORKER_TIMEOUT * time.Second):
 		logger.Println("Got Worker timeout, was not able to get a worker!")
 		return respondError(c, http.StatusServiceUnavailable, requestID, testID, logBuffer, "Timeout in getting a worker!")
@@ -238,7 +246,7 @@ func (s *server) handleRun(c *echo.Context) error {
 		logger.Println("Finished worker cleanup")
 
 		logger.Println("Adding new worker")
-		if err := s.workers[req.Language].AddWorkers(1); err != nil {
+		if err := workers.AddWorkers(1); err != nil {
 			logger.Printf("could not create new worker: %v", err)
 			return
 		}

control-service/worker_languages.go

@@ -0,0 +1,29 @@
+package main
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/mxschmitt/try-playwright/internal/workertypes"
+)
+
+func parseWorkerLanguages(value string) ([]workertypes.WorkerLanguage, error) {
+	if strings.TrimSpace(value) == "" {
+		return append([]workertypes.WorkerLanguage(nil), workertypes.SUPPORTED_LANGUAGES...), nil
+	}
+
+	languages := make([]workertypes.WorkerLanguage, 0)
+	seen := map[workertypes.WorkerLanguage]bool{}
+	for _, item := range strings.Split(value, ",") {
+		language := workertypes.WorkerLanguage(strings.TrimSpace(item))
+		if !language.IsValid() {
+			return nil, fmt.Errorf("invalid language in 'WORKER_LANGUAGES': %q", language)
+		}
+		if seen[language] {
+			return nil, fmt.Errorf("duplicate language in 'WORKER_LANGUAGES': %q", language)
+		}
+		seen[language] = true
+		languages = append(languages, language)
+	}
+	return languages, nil
+}

control-service/worker_languages_test.go

@@ -0,0 +1,64 @@
+package main
+
+import (
+	"reflect"
+	"testing"
+
+	"github.com/mxschmitt/try-playwright/internal/workertypes"
+)
+
+func TestParseWorkerLanguages(t *testing.T) {
+	tests := []struct {
+		name    string
+		value   string
+		want    []workertypes.WorkerLanguage
+		wantErr bool
+	}{
+		{
+			name:  "defaults to all supported languages",
+			value: "",
+			want:  workertypes.SUPPORTED_LANGUAGES,
+		},
+		{
+			name:  "selects one language",
+			value: "javascript",
+			want:  []workertypes.WorkerLanguage{workertypes.WorkerLanguageJavaScript},
+		},
+		{
+			name:  "trims comma-separated languages",
+			value: " python, java ",
+			want: []workertypes.WorkerLanguage{
+				workertypes.WorkerLanguagePython,
+				workertypes.WorkerLanguageJava,
+			},
+		},
+		{
+			name:    "rejects an unsupported language",
+			value:   "javascript,ruby",
+			wantErr: true,
+		},
+		{
+			name:    "rejects a duplicate language",
+			value:   "javascript,javascript",
+			wantErr: true,
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			got, err := parseWorkerLanguages(test.value)
+			if test.wantErr {
+				if err == nil {
+					t.Fatal("parseWorkerLanguages() did not return an error")
+				}
+				return
+			}
+			if err != nil {
+				t.Fatalf("parseWorkerLanguages() returned an error: %v", err)
+			}
+			if !reflect.DeepEqual(got, test.want) {
+				t.Fatalf("parseWorkerLanguages() = %v, want %v", got, test.want)
+			}
+		})
+	}
+}

k8/control-deployment.yaml.tpl

@@ -19,6 +19,8 @@ spec:
         - env:
             - name: WORKER_COUNT
               value: "${WORKER_COUNT}"
+            - name: WORKER_LANGUAGES
+              value: "${WORKER_LANGUAGES}"
             - name: CONTROL_HTTP_PORT
               value: "8080"
             - name: ETCD_ENDPOINT