feat: Expose more detail in dev server errors [FUN-701] (#522)

Mike Zorn · web-flow · commit 553525af0fef · 2025-04-15T13:14:20.000-07:00
Expose more details about dev server errors like what thing wasn't found. Requested in #520.
diff --git a/internal/dev_server/api/delete_flag_override.go b/internal/dev_server/api/delete_flag_override.go
@@ -11,7 +11,7 @@ import (
 func (s server) DeleteFlagOverride(ctx context.Context, request DeleteFlagOverrideRequestObject) (DeleteFlagOverrideResponseObject, error) {
 	err := model.DeleteOverride(ctx, request.ProjectKey, request.FlagKey)
 	if err != nil {
-		if errors.Is(err, model.ErrNotFound) {
+		if errors.As(err, &model.ErrNotFound{}) {
 			return DeleteFlagOverride404Response{}, nil
 		}
 		return nil, err
diff --git a/internal/dev_server/api/post_add_project.go b/internal/dev_server/api/post_add_project.go
@@ -21,10 +21,10 @@ func (s server) PostAddProject(ctx context.Context, request PostAddProjectReques
 	store := model.StoreFromContext(ctx)
 	project, err := model.CreateProject(ctx, request.ProjectKey, request.Body.SourceEnvironmentKey, request.Body.Context)
 	switch {
-	case errors.Is(err, model.ErrAlreadyExists):
+	case errors.As(err, &model.ErrAlreadyExists{}):
 		return PostAddProject409JSONResponse{
 			Code:    "conflict",
-			Message: "project already exists",
+			Message: err.Error(),
 		}, nil
 	case err != nil:
 		return nil, err
diff --git a/internal/dev_server/api/put_override_flag.go b/internal/dev_server/api/put_override_flag.go
@@ -14,7 +14,7 @@ func (s server) PutOverrideFlag(ctx context.Context, request PutOverrideFlagRequ
 	}
 	override, err := model.UpsertOverride(ctx, request.ProjectKey, request.FlagKey, *request.Body)
 	if err != nil {
-		if errors.As(err, &model.Error{}) {
+		if errors.As(err, &model.ErrNotFound{}) {
 			return PutOverrideFlag400JSONResponse{
 				ErrorResponseJSONResponse{
 					Code:    "invalid_request",
diff --git a/internal/dev_server/db/sqlite.go b/internal/dev_server/db/sqlite.go
@@ -54,7 +54,7 @@ func (s *Sqlite) GetDevProject(ctx context.Context, key string) (*model.Project,
 
 	if err := row.Scan(&project.Key, &project.SourceEnvironmentKey, &contextData, &project.LastSyncTime, &flagStateData); err != nil {
 		if errors.Is(err, sql.ErrNoRows) {
-			return nil, errors.Wrapf(model.ErrNotFound, "no project found with key, '%s'", key)
+			return nil, model.NewErrNotFound("project", key)
 		}
 		return nil, err
 	}
@@ -181,7 +181,7 @@ SELECT 1 FROM projects WHERE key = ?
 		return
 	}
 	if projects.Next() {
-		err = model.ErrAlreadyExists
+		err = model.NewErrAlreadyExists("project", project.Key)
 		return
 	}
 	err = projects.Close()
@@ -343,7 +343,7 @@ func (s *Sqlite) DeactivateOverride(ctx context.Context, projectKey, flagKey str
 	var version int
 	if err := row.Scan(&version); err != nil {
 		if errors.Is(err, sql.ErrNoRows) {
-			return 0, errors.Wrapf(model.ErrNotFound, "no override found for flag with key, '%s', in project with key, '%s'", projectKey, flagKey)
+			return 0, errors.Wrapf(model.NewErrNotFound("flag", flagKey), "no override in project %s", projectKey)
 		}
 		return 0, err
 	}
diff --git a/internal/dev_server/db/sqlite_test.go b/internal/dev_server/db/sqlite_test.go
@@ -103,7 +103,7 @@ func TestDBFunctions(t *testing.T) {
 
 	t.Run("InsertProject returns ErrAlreadyExists if the project already exists", func(t *testing.T) {
 		err := store.InsertProject(ctx, projects[0])
-		assert.Equal(t, model.ErrAlreadyExists, err)
+		assert.ErrorAs(t, err, &model.ErrAlreadyExists{})
 	})
 
 	t.Run("GetDevProjectKeys returns keys in projects", func(t *testing.T) {
@@ -120,7 +120,7 @@ func TestDBFunctions(t *testing.T) {
 	t.Run("GetDevProject returns ErrNotFound for fake project keys", func(t *testing.T) {
 		p, err := store.GetDevProject(ctx, "THIS-DOES-NOT-EXIST")
 		assert.Nil(t, p)
-		assert.ErrorIs(t, err, model.ErrNotFound)
+		assert.ErrorAs(t, err, &model.ErrNotFound{})
 	})
 
 	t.Run("GetDevProject returns project", func(t *testing.T) {
@@ -303,7 +303,7 @@ func TestDBFunctions(t *testing.T) {
 
 	t.Run("DeactivateOverride returns error when override not found", func(t *testing.T) {
 		_, err := store.DeactivateOverride(ctx, projects[0].Key, "nope")
-		assert.ErrorIs(t, err, model.ErrNotFound)
+		assert.ErrorAs(t, err, &model.ErrNotFound{})
 	})
 
 	t.Run("DeactivateOverride sets the override inactive and returns the current version", func(t *testing.T) {
diff --git a/internal/dev_server/model/err_already_exists.go b/internal/dev_server/model/err_already_exists.go
@@ -0,0 +1,19 @@
+package model
+
+import "fmt"
+
+type ErrAlreadyExists struct {
+	kind string
+	key  string
+}
+
+func (e ErrAlreadyExists) Error() string {
+	return fmt.Sprintf("%s %s already exists", e.kind, e.key)
+}
+
+func NewErrAlreadyExists(kind, key string) ErrAlreadyExists {
+	return ErrAlreadyExists{
+		kind: kind,
+		key:  key,
+	}
+}
diff --git a/internal/dev_server/model/err_not_found.go b/internal/dev_server/model/err_not_found.go
@@ -0,0 +1,19 @@
+package model
+
+import "fmt"
+
+type ErrNotFound struct {
+	kind string
+	key  string
+}
+
+func (e ErrNotFound) Error() string {
+	return fmt.Sprintf("%s %s not found", e.kind, e.key)
+}
+
+func NewErrNotFound(kind, key string) ErrNotFound {
+	return ErrNotFound{
+		kind: kind,
+		key:  key,
+	}
+}
diff --git a/internal/dev_server/model/error.go b/internal/dev_server/model/error.go
diff --git a/internal/dev_server/model/override.go b/internal/dev_server/model/override.go
@@ -33,7 +33,7 @@ func getFlagStateForFlagAndProject(ctx context.Context, projectKey, flagKey stri
 		}
 	}
 	if !flagExists {
-		return FlagState{}, ErrNotFound
+		return FlagState{}, NewErrNotFound("flag", flagKey)
 	}
 	return project.AllFlagsState[flagKey], nil
 }
diff --git a/internal/dev_server/model/override_test.go b/internal/dev_server/model/override_test.go
@@ -58,7 +58,7 @@ func TestUpsertOverride(t *testing.T) {
 
 		_, err := model.UpsertOverride(ctx, projKey, flagKey, ldValue)
 		assert.Error(t, err)
-		assert.ErrorIs(t, model.ErrNotFound, err)
+		assert.ErrorAs(t, err, &model.ErrNotFound{})
 	})
 
 	t.Run("store fails to upsert, returns error", func(t *testing.T) {
diff --git a/internal/dev_server/model/store.go b/internal/dev_server/model/store.go
@@ -2,7 +2,6 @@ package model
 
 import (
 	"context"
-	"errors"
 	"io"
 	"net/http"
 
@@ -52,6 +51,3 @@ func StoreMiddleware(store Store) mux.MiddlewareFunc {
 		})
 	}
 }
-
-var ErrNotFound = errors.New("not found")
-var ErrAlreadyExists = errors.New("already exists")
diff --git a/internal/dev_server/model/sync.go b/internal/dev_server/model/sync.go
@@ -30,7 +30,7 @@ func CreateOrSyncProject(ctx context.Context, settings InitialProjectSettings) e
 	var project Project
 	project, createError := CreateProject(ctx, settings.ProjectKey, settings.EnvKey, settings.Context)
 	if createError != nil {
-		if !errors.Is(createError, ErrAlreadyExists) {
+		if !errors.As(createError, &ErrAlreadyExists{}) {
 			return createError
 		}
 
diff --git a/internal/dev_server/model/sync_test.go b/internal/dev_server/model/sync_test.go
@@ -174,7 +174,7 @@ func TestInitialSync(t *testing.T) {
 		api.EXPECT().GetSdkKey(gomock.Any(), projKey, sourceEnvKey).Return(sdkKey, nil)
 		sdk.EXPECT().GetAllFlagsState(gomock.Any(), gomock.Any(), sdkKey).Return(allFlagsState, nil)
 		api.EXPECT().GetAllFlags(gomock.Any(), projKey).Return(allFlags, nil)
-		store.EXPECT().InsertProject(gomock.Any(), gomock.Any()).Return(model.ErrAlreadyExists)
+		store.EXPECT().InsertProject(gomock.Any(), gomock.Any()).Return(model.NewErrAlreadyExists("project", projKey))
 
 		input := model.InitialProjectSettings{
 			Enabled:    true,
diff --git a/internal/dev_server/sdk/store_facade.go b/internal/dev_server/sdk/store_facade.go
@@ -2,7 +2,6 @@ package sdk
 
 import (
 	"context"
-	"fmt"
 	"log"
 	"net/http"
 
@@ -16,9 +15,9 @@ import (
 //   - This is in the context of flag delivery which has pretty consistent semantics for what's an error across handlers.
 func WriteError(ctx context.Context, w http.ResponseWriter, err error) {
 	switch {
-	case errors.Is(err, model.ErrNotFound):
+	case errors.As(err, &model.ErrNotFound{}):
 		projectKey := GetProjectKeyFromContext(ctx)
-		message := fmt.Sprintf("project, %s, not found", projectKey)
+		message := err.Error()
 		log.Println(message)
 		log.Printf("To add your project to the dev server, call `ldcli dev-server add-project --project %s --source {SOURCE_ENV_KEY}", projectKey)
 		http.Error(w, message, http.StatusNotFound)

Original file line number	Diff line number	Diff line change
`@@ -11,7 +11,7 @@ import (`
`11`	`11`	`func (s server) DeleteFlagOverride(ctx context.Context, request DeleteFlagOverrideRequestObject) (DeleteFlagOverrideResponseObject, error) {`
`12`	`12`	`err := model.DeleteOverride(ctx, request.ProjectKey, request.FlagKey)`
`13`	`13`	`if err != nil {`
`14`		`- if errors.Is(err, model.ErrNotFound) {`
	`14`	`+ if errors.As(err, &model.ErrNotFound{}) {`
`15`	`15`	`return DeleteFlagOverride404Response{}, nil`
`16`	`16`	`}`
`17`	`17`	`return nil, err`
Original file line number	Diff line number	Diff line change
`@@ -14,7 +14,7 @@ func (s server) PutOverrideFlag(ctx context.Context, request PutOverrideFlagRequ`
`14`	`14`	`}`
`15`	`15`	`override, err := model.UpsertOverride(ctx, request.ProjectKey, request.FlagKey, *request.Body)`
`16`	`16`	`if err != nil {`
`17`		`- if errors.As(err, &model.Error{}) {`
	`17`	`+ if errors.As(err, &model.ErrNotFound{}) {`
`18`	`18`	`return PutOverrideFlag400JSONResponse{`
`19`	`19`	`ErrorResponseJSONResponse{`
`20`	`20`	`Code: "invalid_request",`
Original file line number	Diff line number	Diff line change
`@@ -54,7 +54,7 @@ func (s Sqlite) GetDevProject(ctx context.Context, key string) (model.Project,`
`54`	`54`
`55`	`55`	`if err := row.Scan(&project.Key, &project.SourceEnvironmentKey, &contextData, &project.LastSyncTime, &flagStateData); err != nil {`
`56`	`56`	`if errors.Is(err, sql.ErrNoRows) {`
`57`		`- return nil, errors.Wrapf(model.ErrNotFound, "no project found with key, '%s'", key)`
	`57`	`+ return nil, model.NewErrNotFound("project", key)`
`58`	`58`	`}`
`59`	`59`	`return nil, err`
`60`	`60`	`}`
`@@ -181,7 +181,7 @@ SELECT 1 FROM projects WHERE key = ?`
`181`	`181`	`return`
`182`	`182`	`}`
`183`	`183`	`if projects.Next() {`
`184`		`- err = model.ErrAlreadyExists`
	`184`	`+ err = model.NewErrAlreadyExists("project", project.Key)`
`185`	`185`	`return`
`186`	`186`	`}`
`187`	`187`	`err = projects.Close()`
`@@ -343,7 +343,7 @@ func (s *Sqlite) DeactivateOverride(ctx context.Context, projectKey, flagKey str`
`343`	`343`	`var version int`
`344`	`344`	`if err := row.Scan(&version); err != nil {`
`345`	`345`	`if errors.Is(err, sql.ErrNoRows) {`
`346`		`- return 0, errors.Wrapf(model.ErrNotFound, "no override found for flag with key, '%s', in project with key, '%s'", projectKey, flagKey)`
	`346`	`+ return 0, errors.Wrapf(model.NewErrNotFound("flag", flagKey), "no override in project %s", projectKey)`
`347`	`347`	`}`
`348`	`348`	`return 0, err`
`349`	`349`	`}`
Original file line number	Diff line number	Diff line change
`@@ -33,7 +33,7 @@ func getFlagStateForFlagAndProject(ctx context.Context, projectKey, flagKey stri`
`33`	`33`	`}`
`34`	`34`	`}`
`35`	`35`	`if !flagExists {`
`36`		`- return FlagState{}, ErrNotFound`
	`36`	`+ return FlagState{}, NewErrNotFound("flag", flagKey)`
`37`	`37`	`}`
`38`	`38`	`return project.AllFlagsState[flagKey], nil`
`39`	`39`	`}`