refactor: normalize error handling

api/routes.go

@@ -113,10 +113,10 @@ func ApplyPermissionAgent(logger *logrus.Logger, conf *foodme.Configuration, htt
 		}
 
 		// Establish sql handler
-		agent := foodme.NewPermissionAgent(conf, httpClient)
-		if agent == nil {
+		agent, err := foodme.NewPermissionAgent(conf, httpClient)
+		if err != nil {
 			logger.WithFields(logrus.Fields{"component": "api"}).Errorf("[%p] Failed to create permission agent", r)
-			HandleErrorResponse(logger, w, http.StatusInternalServerError, "Failed to create permission agent")
+			HandleErrorResponse(logger, w, http.StatusInternalServerError, "Failed to create permission agent: "+err.Error())
 			return
 		}
 

api/routes_test.go

@@ -222,7 +222,7 @@ func TestApplyPermissionAgent(t *testing.T) {
 	r = &http.Request{Body: &MockBody{Body: "{\"username\":\"test\", \"sql\":\"select * from pets\"}"}}
 	handler(w, r)
 	assert.DeepEqual(t, w.headers.headers, []int{500})
-	assert.DeepEqual(t, w.buffer.buffer, []byte("{\"detail\":\"Failed to create permission agent\"}\n"))
+	assert.DeepEqual(t, w.buffer.buffer, []byte("{\"detail\":\"Failed to create permission agent: unknown permission agent type: \"}\n"))
 
 	// Missing SQL handler
 	conf.PermissionAgentEnabled = true

api/server.go

@@ -9,7 +9,7 @@ import (
 	"github.com/sirupsen/logrus"
 )
 
-func Cleaner(logger *logrus.Logger, period int) {
+func StartCleaner(logger *logrus.Logger, period int) {
 	logger.WithFields(logrus.Fields{"component": "cleaner"}).Infof("Starting the Cleaner")
 	t := time.NewTicker(time.Duration(period) * time.Second)
 	go func() {
@@ -28,7 +28,7 @@ func Cleaner(logger *logrus.Logger, period int) {
 func Start(logger *logrus.Logger, conf *foodme.Configuration) {
 	logger.WithFields(logrus.Fields{"component": "api"}).Infof("Starting the API")
 
-	go Cleaner(logger, conf.ApiGarbageCollectionPeriod)
+	StartCleaner(logger, conf.ApiGarbageCollectionPeriod)
 	server := http.NewServeMux()
 	httpClient := &http.Client{}
 	server.HandleFunc("POST /connection", CreateNewConnection(logger, conf.ApiUsernameLifetime))

internal/handler.go

@@ -21,11 +21,10 @@ func GetHandler(conf *Configuration, logger *logrus.Logger, httpClient IHttpClie
 	}
 
 	var sqlHandler ISQLHandler
-	var err error
 	if conf.PermissionAgentEnabled {
-		pAgent := NewPermissionAgent(conf, httpClient)
-		if pAgent == nil {
-			return nil, fmt.Errorf("unsupported permission agent")
+		pAgent, err := NewPermissionAgent(conf, httpClient)
+		if err != nil {
+			return nil, fmt.Errorf("failed to create permission agent: %w", err)
 		}
 		sqlHandler, err = NewSQLHandler(conf.DestinationDatabaseType, logger, pAgent)
 		if err != nil {

internal/permission_agent.go

@@ -1,5 +1,7 @@
 package foodme
 
+import "fmt"
+
 type SelectFilters struct {
 	WhereFilters []string      `json:"whereFilters"`
 	JoinFilters  []*JoinFilter `json:"joinFilters"`
@@ -10,7 +12,7 @@ type JoinFilter struct {
 	Conditions string `json:"conditions"`
 }
 
-func NewPermissionAgent(conf *Configuration, httpClient IHttpClient) IPermissionAgent {
+func NewPermissionAgent(conf *Configuration, httpClient IHttpClient) (IPermissionAgent, error) {
 	switch conf.PermissionAgentType {
 	case "opa":
 		return NewOPASQL(
@@ -21,10 +23,10 @@ func NewPermissionAgent(conf *Configuration, httpClient IHttpClient) IPermission
 			conf.PermissionAgentOPADeleteQuery,
 			conf.PermissionAgentOPAStringEscapeCharacter,
 			httpClient,
-		)
+		), nil
 	case "http":
-		return NewHTTPPermissionAgent(conf.PermissionAgentHTTPDDLEndpoint, conf.PermissionAgentHTTPSelectEndpoint, httpClient)
+		return NewHTTPPermissionAgent(conf.PermissionAgentHTTPDDLEndpoint, conf.PermissionAgentHTTPSelectEndpoint, httpClient), nil
 	default:
-		return nil
+		return nil, fmt.Errorf("unknown permission agent type: %s", conf.PermissionAgentType)
 	}
 }

internal/permission_agent_test.go

@@ -9,16 +9,18 @@ import (
 func TestNewPermissionAgent(t *testing.T) {
 	conf, err := NewConfiguration([]string{"--destination-database-type", "postgres", "--destination-host", "localhost", "--destination-port", "5432"})
 	assert.NilError(t, err)
-	agent := NewPermissionAgent(conf, nil)
-	assert.Assert(t, agent == nil)
+	_, err = NewPermissionAgent(conf, nil)
+	assert.Error(t, err, "unknown permission agent type: ")
 
 	conf, err = NewConfiguration([]string{"--destination-database-type", "postgres", "--destination-host", "localhost", "--destination-port", "5432", "--permission-agent-type", "opa"})
 	assert.NilError(t, err)
-	agent = NewPermissionAgent(conf, nil)
+	agent, err := NewPermissionAgent(conf, nil)
+	assert.NilError(t, err)
 	assert.Assert(t, agent != nil)
 
 	conf, err = NewConfiguration([]string{"--destination-database-type", "postgres", "--destination-host", "localhost", "--destination-port", "5432", "--permission-agent-type", "http"})
 	assert.NilError(t, err)
-	agent = NewPermissionAgent(conf, nil)
+	agent, err = NewPermissionAgent(conf, nil)
+	assert.NilError(t, err)
 	assert.Assert(t, agent != nil)
 }

internal/postgres_sql_handler.go

@@ -20,7 +20,7 @@ type PostgresSQLHandler struct {
 	userInfo     map[string]interface{}
 }
 
-func NewPostgresSQLHandler(logger *logrus.Logger, pAgent IPermissionAgent) ISQLHandler {
+func NewPostgresSQLHandler(logger *logrus.Logger, pAgent IPermissionAgent) *PostgresSQLHandler {
 	return &PostgresSQLHandler{Logger: logger, PermissionAgent: pAgent, withTables: make(map[string]string)}
 }