Merge pull request #25 from ls1intum/add-authorization-support

Switch to reader and writer auth

Author: KevinGruber2001

chart/Chart.yaml

@@ -5,7 +5,7 @@ description: A Gradle Build Cache server with Redis backend for Theia IDE deploy
 type: application
 
 # Chart version - bump for breaking changes
-version: 0.3.0
+version: 0.3.1
 
 # Application version - matches the cache server version
 appVersion: "0.1.0"

chart/templates/auth-secrets.yaml

@@ -0,0 +1,27 @@
+{{- if and .Values.enabled .Values.auth.enabled }}
+# Read-only cache credentials (for Theia IDE / students)
+apiVersion: v1
+kind: Secret
+metadata:
+  name: {{ .Release.Name }}-cache-reader
+  labels:
+    app: {{ .Release.Name }}
+    role: reader
+type: kubernetes.io/basic-auth
+data:
+  username: {{ .Values.auth.reader.username | b64enc | quote }}
+  password: {{ .Values.auth.reader.password | b64enc | quote }}
+---
+# Read-write cache credentials (for CI/CD, admin, cache pre-warming)
+apiVersion: v1
+kind: Secret
+metadata:
+  name: {{ .Release.Name }}-cache-writer
+  labels:
+    app: {{ .Release.Name }}
+    role: writer
+type: kubernetes.io/basic-auth
+data:
+  username: {{ .Values.auth.writer.username | b64enc | quote }}
+  password: {{ .Values.auth.writer.password | b64enc | quote }}
+{{- end }}

chart/templates/configmap.yaml

@@ -28,8 +28,10 @@ data:
     auth:
       enabled: {{ .Values.auth.enabled }}
       {{- if .Values.auth.enabled }}
-      users:
-        - username: {{ .Values.auth.username | quote }}
+      reader:
+        username: {{ .Values.auth.reader.username | quote }}
+      writer:
+        username: {{ .Values.auth.writer.username | quote }}
       {{- end }}
 
     logging:

chart/templates/deployment.yaml

@@ -49,11 +49,16 @@ spec:
                   name: {{ .Release.Name }}-redis-secret
                   key: redis-password
             {{- if .Values.auth.enabled }}
-            - name: CACHE_PASSWORD
+            - name: CACHE_READER_PASSWORD
               valueFrom:
                 secretKeyRef:
-                  name: {{ .Release.Name }}-redis-secret
-                  key: cache-password
+                  name: {{ .Release.Name }}-cache-reader
+                  key: password
+            - name: CACHE_WRITER_PASSWORD
+              valueFrom:
+                secretKeyRef:
+                  name: {{ .Release.Name }}-cache-writer
+                  key: password
             {{- end }}
           args:
             - --config

chart/templates/secrets.yaml chart/templates/redis-secret.yamlchart/templates/secrets.yaml renamed to chart/templates/redis-secret.yaml

@@ -15,5 +15,4 @@ data:
   {{- else }}
   redis-password: {{ randAlphaNum 32 | b64enc}}
   {{- end }}
-  cache-password: {{ .Values.auth.password | b64enc | quote}}
 {{- end }}

chart/values.yaml

@@ -9,12 +9,21 @@ image:
   tag: "main"
   pullPolicy: IfNotPresent
 
-# Authentication credentials
+# Authentication credentials (role-based)
+# reader: read-only access (for Theia IDE / students)
+# writer: read-write access (for CI/CD, admin, cache pre-warming)
 auth:
   enabled: true
-  username: "gradle"
-  # IMPORTANT: Change this password in production!
-  password: "changeme"
+  reader:
+    username: "reader"
+    # IMPORTANT: Change this password in production!
+    # optimaly from github envrionment secrets
+    password: "changeme-reader"
+  writer:
+    username: "writer"
+    # IMPORTANT: Change this password in production!
+    # optimaly from github envrionment secrets
+    password: "changeme-writer"
 
 # Resource limits
 resources:

src/internal/config/config.go

@@ -42,8 +42,9 @@ type CacheConfig struct {
 }
 
 type AuthConfig struct {
-	Enabled bool       `mapstructure:"enabled"`
-	Users   []UserAuth `mapstructure:"users"`
+	Enabled bool     `mapstructure:"enabled"`
+	Reader  UserAuth `mapstructure:"reader"`
+	Writer  UserAuth `mapstructure:"writer"`
 }
 
 type UserAuth struct {
@@ -106,37 +107,29 @@ func Load(configPath string) (*Config, error) {
 	// Bind specific environment variables
 	v.BindEnv("storage.password", "REDIS_PASSWORD")
 
-	v.BindEnv("auth.users.0.password", "CACHE_PASSWORD")
+	v.BindEnv("auth.reader.password", "CACHE_READER_PASSWORD")
+	v.BindEnv("auth.writer.password", "CACHE_WRITER_PASSWORD")
+
 	v.BindEnv("sentry.dsn", "SENTRY_DSN")
 
 	var cfg Config
 	if err := v.Unmarshal(&cfg); err != nil {
 		return nil, fmt.Errorf("failed to unmarshal config: %w", err)
 	}
 
-	// Handle CACHE_PASSWORD environment variable for default user
-	if cachePassword := v.GetString("CACHE_PASSWORD"); cachePassword != "" {
-		if len(cfg.Auth.Users) > 0 {
-			cfg.Auth.Users[0].Password = cachePassword
-		}
-	}
-
 	return &cfg, nil
 }
 
 func (c *Config) Validate() error {
 	if c.Storage.Addr == "" {
 		return fmt.Errorf("storage.addr is required")
 	}
-	if c.Auth.Enabled && len(c.Auth.Users) == 0 {
-		return fmt.Errorf("auth.users is required when auth is enabled")
-	}
-	for i, user := range c.Auth.Users {
-		if user.Username == "" {
-			return fmt.Errorf("auth.users[%d].username is required", i)
+	if c.Auth.Enabled {
+		if c.Auth.Reader.Username == "" || c.Auth.Reader.Password == "" {
+			return fmt.Errorf("auth.reader.username and auth.reader.password are required when auth is enabled")
 		}
-		if user.Password == "" {
-			return fmt.Errorf("auth.users[%d].password is required", i)
+		if c.Auth.Writer.Username == "" || c.Auth.Writer.Password == "" {
+			return fmt.Errorf("auth.writer.username and auth.writer.password are required when auth is enabled")
 		}
 	}
 	if c.Server.TLS.Enabled {

src/internal/middleware/auth.go

@@ -8,13 +8,8 @@ import (
 	"github.com/kevingruber/gradle-cache/internal/config"
 )
 
-// BasicAuth creates a middleware that validates HTTP Basic Authentication.
-func BasicAuth(users []config.UserAuth) gin.HandlerFunc {
-	// Build a map for O(1) lookup
-	credentials := make(map[string]string, len(users))
-	for _, user := range users {
-		credentials[user.Username] = user.Password
-	}
+// CacheAuth creates a middleware that validates HTTP Basic Authentication
+func CacheAuth(auth config.AuthConfig, requireWriter bool) gin.HandlerFunc {
 
 	return func(c *gin.Context) {
 		username, password, ok := c.Request.BasicAuth()
@@ -24,22 +19,23 @@ func BasicAuth(users []config.UserAuth) gin.HandlerFunc {
 			return
 		}
 
-		expectedPassword, userExists := credentials[username]
-		if !userExists {
+		// Check credentials
+		isReader := username == auth.Reader.Username &&
+			subtle.ConstantTimeCompare([]byte(password), []byte(auth.Reader.Password)) == 1
+		isWriter := username == auth.Writer.Username &&
+			subtle.ConstantTimeCompare([]byte(password), []byte(auth.Writer.Password)) == 1
+
+		if !isReader && !isWriter {
 			c.Header("WWW-Authenticate", `Basic realm="Gradle Build Cache"`)
 			c.AbortWithStatus(http.StatusUnauthorized)
 			return
 		}
 
-		// Use constant-time comparison to prevent timing attacks
-		if subtle.ConstantTimeCompare([]byte(password), []byte(expectedPassword)) != 1 {
-			c.Header("WWW-Authenticate", `Basic realm="Gradle Build Cache"`)
-			c.AbortWithStatus(http.StatusUnauthorized)
+		if requireWriter && !isWriter {
+			c.AbortWithStatus(http.StatusForbidden)
 			return
 		}
 
-		// Store username in context for logging/metrics
-		c.Set("username", username)
 		c.Next()
 	}
 }

src/internal/server/server.go

@@ -88,13 +88,19 @@ func (s *Server) setupRoutes() {
 
 	// Create cache group with optional auth
 	cacheGroup := s.router.Group("/cache")
-	if s.cfg.Auth.Enabled {
-		cacheGroup.Use(middleware.BasicAuth(s.cfg.Auth.Users))
-	}
 
-	cacheGroup.GET("/:key", cacheHandler.Get)
-	cacheGroup.PUT("/:key", cacheHandler.Put)
-	cacheGroup.HEAD("/:key", cacheHandler.Head)
+	cacheGroup.GET("/:key", s.cacheAuth(false), cacheHandler.Get)
+	cacheGroup.HEAD("/:key", s.cacheAuth(false), cacheHandler.Head)
+	cacheGroup.PUT("/:key", s.cacheAuth(true), cacheHandler.Put)
+}
+
+func (s *Server) cacheAuth(requireWriter bool) gin.HandlerFunc {
+	if !s.cfg.Auth.Enabled {
+		return func(c *gin.Context) {
+			c.Next()
+		}
+	}
+	return middleware.CacheAuth(s.cfg.Auth, requireWriter)
 }
 
 // handlePing is a simple health check endpoint.