feat(config): enhance environment variable expansion in dependencies and services

Author: yarlson

pkg/config/config.go

@@ -117,10 +117,11 @@ func getDefaultConfig(baseName, version string) (*Dependency, bool) {
 	return &dep, true
 }
 
-// UnmarshalYAML is a custom unmarshaler that lets you handle both string-based
-// and map-based dependencies.
+// UnmarshalYAML is a custom unmarshaler that handles both string-based
+// dependencies (like "mysql:8") and map-based dependencies, plus expands env vars.
 func (d *Dependency) UnmarshalYAML(node *yaml.Node) error {
 	switch node.Tag {
+
 	case "!!str":
 		// If the node is just a string (e.g. "postgres:16"), parse it.
 		value := node.Value
@@ -130,6 +131,17 @@ func (d *Dependency) UnmarshalYAML(node *yaml.Node) error {
 			// We have a base name + version
 			base, version := parts[0], parts[1]
 			if defaultDep, ok := getDefaultConfig(base, version); ok {
+				// Expand env placeholders in the default config
+				for i, envLine := range defaultDep.Env {
+					expanded, err := expandWithEnvAndDefault(envLine)
+					if err != nil {
+						return fmt.Errorf(
+							"failed expanding env in default config for %q: %w",
+							base, err,
+						)
+					}
+					defaultDep.Env[i] = expanded
+				}
 				*d = *defaultDep
 			} else {
 				// fallback for unknown base (e.g., "foobar:1.0")
@@ -140,9 +152,20 @@ func (d *Dependency) UnmarshalYAML(node *yaml.Node) error {
 			// Only a base name (e.g., "redis")
 			base := parts[0]
 			if defaultDep, ok := getDefaultConfig(base, "latest"); ok {
+				// Expand env placeholders
+				for i, envLine := range defaultDep.Env {
+					expanded, err := expandWithEnvAndDefault(envLine)
+					if err != nil {
+						return fmt.Errorf(
+							"failed expanding env in default config for %q: %w",
+							base, err,
+						)
+					}
+					defaultDep.Env[i] = expanded
+				}
 				*d = *defaultDep
 			} else {
-				// fallback for unknown base (e.g., "foobar")
+				// fallback for unknown base
 				d.Name = base
 				d.Image = base
 			}
@@ -156,6 +179,17 @@ func (d *Dependency) UnmarshalYAML(node *yaml.Node) error {
 		if err := node.Decode(&tmp); err != nil {
 			return fmt.Errorf("failed to decode dependency map: %w", err)
 		}
+		// Expand placeholders in tmp.Env
+		for i, envLine := range tmp.Env {
+			expanded, err := expandWithEnvAndDefault(envLine)
+			if err != nil {
+				return fmt.Errorf(
+					"failed to expand env for dependency %q: %w",
+					tmp.Name, err,
+				)
+			}
+			tmp.Env[i] = expanded
+		}
 		*d = Dependency(tmp)
 		return nil
 
@@ -175,26 +209,68 @@ type Hooks struct {
 	Post string `yaml:"post"`
 }
 
-func ParseConfig(data []byte) (*Config, error) {
-	// Load any .env file from the current directory
-	_ = godotenv.Load()
+// expandWithEnvAndDefault expands environment variables within a single string.
+// It handles `${VAR:-default}` and `${VAR:?error message}` syntax. If a required
+// variable is missing, it returns an error. Otherwise, it returns the expanded
+// string and a nil error.
+func expandWithEnvAndDefault(input string) (string, error) {
+	var expansionErr error
+
+	expanded := os.Expand(input, func(key string) string {
+		val, err := expandOneVar(key)
+		if err != nil && expansionErr == nil {
+			// capture the first error
+			expansionErr = err
+		}
+		return val
+	})
 
-	// Process environment variables with default values
-	expandedData := os.Expand(string(data), func(key string) string {
-		// Check if there's a default value specified
+	// if expansionErr != nil, expanded might be partially filled, but we return the error
+	return expanded, expansionErr
+}
+
+// expandOneVar handles a single ${...} expression inside os.Expand.
+func expandOneVar(key string) (string, error) {
+	// Check for ":-" = default fallback
+	if strings.Contains(key, ":-") {
 		parts := strings.SplitN(key, ":-", 2)
 		envKey := parts[0]
-
-		if value, exists := os.LookupEnv(envKey); exists {
-			return value
+		defaultVal := parts[1]
+		if val, ok := os.LookupEnv(envKey); ok {
+			return val, nil
 		}
+		return defaultVal, nil
+	}
 
-		// Return default value if specified, empty string otherwise
-		if len(parts) > 1 {
-			return parts[1]
+	// Check for ":?" = required variable
+	if strings.Contains(key, ":?") {
+		parts := strings.SplitN(key, ":?", 2)
+		envKey := parts[0]
+		errMsg := parts[1]
+		if val, ok := os.LookupEnv(envKey); ok {
+			return val, nil
 		}
-		return ""
-	})
+		// variable not set => return an error
+		return "", fmt.Errorf("required environment variable %s not set: %s", envKey, errMsg)
+	}
+
+	// Otherwise, it's just ${VAR} with no colon
+	if val, ok := os.LookupEnv(key); ok {
+		return val, nil
+	}
+	// Not found in environment => return empty string
+	return "", nil
+}
+
+func ParseConfig(data []byte) (*Config, error) {
+	// Load any .env file from the current directory
+	_ = godotenv.Load()
+
+	// Process environment variables with default values
+	expandedData, err := expandWithEnvAndDefault(string(data))
+	if err != nil {
+		return nil, fmt.Errorf("error expanding environment variables: %v", err)
+	}
 
 	var config Config
 	if err := yaml.Unmarshal([]byte(expandedData), &config); err != nil {

pkg/config/config_test.go

@@ -408,6 +408,8 @@ server:
 services:
   - name: "web"
     image: "nginx:latest"
+    routes:
+      - path: "/"
     port: 80
     volumes:
       - "/absolute/path:/container/path"
@@ -458,3 +460,120 @@ dependencies:
 	expected := []string{"redis_data"}
 	assert.Equal(suite.T(), expected, config.Volumes)
 }
+
+func (suite *ConfigTestSuite) TestParseConfig_EnvExpansionInDefaults_Success() {
+	// We'll set an env var that overrides the default "production-secret" for MySQL.
+	// Then after the test, we'll unset it to avoid side effects in other tests.
+	os.Setenv("MYSQL_ROOT_PASSWORD", "super-secret-password")
+	defer os.Unsetenv("MYSQL_ROOT_PASSWORD")
+
+	yamlData := []byte(`
+project:
+  name: "env-default-test"
+  domain: "example.com"
+  email: "test@example.com"
+server:
+  host: "example.com"
+  port: 22
+  user: "user"
+  ssh_key: "~/.ssh/id_rsa"
+services:
+  - name: "web"
+    image: "nginx:latest"
+    routes:
+      - path: "/"
+    port: 80
+dependencies:
+  - "mysql:5.7"
+`)
+
+	config, err := ParseConfig(yamlData)
+	assert.NoError(suite.T(), err)
+	assert.NotNil(suite.T(), config)
+	assert.Len(suite.T(), config.Dependencies, 1)
+
+	dep := config.Dependencies[0]
+	// The name should come from the default config or be "mysql"
+	assert.Equal(suite.T(), "mysql", dep.Name)
+	// The image should reflect version override => "mysql:5.7"
+	assert.Equal(suite.T(), "mysql:5.7", dep.Image)
+
+	// Check env expansions
+	// Our default config had "MYSQL_ROOT_PASSWORD=${MYSQL_ROOT_PASSWORD:-production-secret}"
+	// We set that env var => we expect "MYSQL_ROOT_PASSWORD=super-secret-password"
+	require := assert.New(suite.T())
+	require.Len(dep.Env, 1)
+	require.Equal("MYSQL_ROOT_PASSWORD=super-secret-password", dep.Env[0])
+}
+
+func (suite *ConfigTestSuite) TestParseConfig_EnvExpansionInServices_Success() {
+	// We'll set an env var that overrides a default in the service env.
+	os.Setenv("MY_SERVICE_VAR", "overridden-value")
+	defer os.Unsetenv("MY_SERVICE_VAR")
+
+	yamlData := []byte(`
+project:
+  name: "service-env-test"
+  domain: "example.com"
+  email: "test@example.com"
+server:
+  host: "example.com"
+  port: 22
+  user: "user"
+  ssh_key: "~/.ssh/id_rsa"
+
+services:
+  - name: "my-service"
+    image: "my-service:latest"
+    routes:
+      - path: "/"
+    port: 8080
+    env:
+      - "MY_VAR=${MY_SERVICE_VAR:-default-value}"
+dependencies: []
+`)
+
+	config, err := ParseConfig(yamlData)
+	assert.NoError(suite.T(), err)
+	assert.NotNil(suite.T(), config)
+	assert.Len(suite.T(), config.Services, 1)
+
+	svc := config.Services[0]
+	require := assert.New(suite.T())
+	require.Len(svc.Env, 1)
+	// Should reflect the env var we set
+	require.Equal("MY_VAR=overridden-value", svc.Env[0])
+}
+
+func (suite *ConfigTestSuite) TestParseConfig_EnvExpansion_RequiredVarMissing() {
+	// We do NOT set the environment variable MY_REQUIRED_VAR, so we expect an error.
+	yamlData := []byte(`
+project:
+  name: "required-var-test"
+  domain: "example.com"
+  email: "test@example.com"
+server:
+  host: "example.com"
+  port: 22
+  user: "user"
+  ssh_key: "~/.ssh/id_rsa"
+
+services:
+  - name: "my-service"
+    image: "my-service:latest"
+    routes:
+      - path: "/"
+    port: 8080
+    env:
+      - "MUST_BE_SET=${MY_REQUIRED_VAR:?must be set!}"
+dependencies: []
+`)
+
+	config, err := ParseConfig(yamlData)
+
+	assert.Error(suite.T(), err)
+	assert.Nil(suite.T(), config)
+	// The error message should say "required environment variable MY_REQUIRED_VAR not set"
+	assert.Contains(suite.T(), err.Error(), "required environment variable MY_REQUIRED_VAR not set")
+	assert.Contains(suite.T(), err.Error(), "must be set!")
+}

pkg/config/default_configs.go

@@ -9,7 +9,7 @@ var defaultConfigs = map[string]Dependency{
 		Ports:   []int{3306},
 		Volumes: []string{"mysql_data:/var/lib/mysql"},
 		Env: []string{
-			"MYSQL_ROOT_PASSWORD=production-secret",
+			"MYSQL_ROOT_PASSWORD=${MYSQL_ROOT_PASSWORD}",
 		},
 	},
 	"postgres": {
@@ -18,7 +18,7 @@ var defaultConfigs = map[string]Dependency{
 		Ports:   []int{5432},
 		Volumes: []string{"postgres_data:/var/lib/postgresql/data"},
 		Env: []string{
-			"POSTGRES_PASSWORD=production-secret",
+			"POSTGRES_PASSWORD=${POSTGRES_PASSWORD}",
 		},
 	},
 	"postgresql": {
@@ -27,7 +27,7 @@ var defaultConfigs = map[string]Dependency{
 		Ports:   []int{5432},
 		Volumes: []string{"postgres_data:/var/lib/postgresql/data"},
 		Env: []string{
-			"POSTGRES_PASSWORD=production-secret",
+			"POSTGRES_PASSWORD=${POSTGRES_PASSWORD}",
 		},
 	},
 	"elasticsearch": {
@@ -54,8 +54,8 @@ var defaultConfigs = map[string]Dependency{
 		Ports:   []int{27017},
 		Volumes: []string{"mongo_data:/data/db"},
 		Env: []string{
-			"MONGO_INITDB_ROOT_USERNAME=root",
-			"MONGO_INITDB_ROOT_PASSWORD=production-secret",
+			"MONGO_INITDB_ROOT_USERNAME=${MONGO_ROOT_USER:mongouser}",
+			"MONGO_INITDB_ROOT_PASSWORD=${MONGO_ROOT_PASSWORD}",
 		},
 	},
 	"redis": {
@@ -70,9 +70,10 @@ var defaultConfigs = map[string]Dependency{
 		Ports: []int{11211},
 	},
 	"rabbitmq": {
-		Name:  "rabbitmq",
-		Image: "rabbitmq:latest",
-		Ports: []int{5672, 15672}, // main + management
+		Name:    "rabbitmq",
+		Image:   "rabbitmq:latest",
+		Ports:   []int{5672, 15672}, // main + management
+		Volumes: []string{"rabbitmq_data:/var/lib/rabbitmq"},
 		Container: &Container{
 			ULimits: []ULimit{
 				{