Improves error reporting

- In concise mode, errors are rendered cleanly at the end of the terminal output
- Silenced cobra error logging to avoid breaking our TUI output
- Added error detection for language host startup
- Added error messages to clarify issues with the klotho sdk installation

cmd/klotho/down.go

@@ -43,7 +43,7 @@ func newDownCmd() *cobra.Command {
 }
 
 func getProjectPath(ctx context.Context, inputPath string) (string, error) {
-	langHost, addr, err := language_host.StartPythonClient(ctx, language_host.DebugConfig{
+	langHost, srvState, err := language_host.StartPythonClient(ctx, language_host.DebugConfig{
 		Port: downConfig.debugPort,
 		Mode: downConfig.debugMode,
 	}, filepath.Dir(inputPath))
@@ -62,15 +62,21 @@ func getProjectPath(ctx context.Context, inputPath string) (string, error) {
 	log.Debug("Waiting for Python server to start")
 	if downConfig.debugMode != "" {
 		// Don't add a timeout in case there are breakpoints in the language host before an address is printed
-		<-addr.HasAddr
+		select {
+		case <-srvState.HasAddr:
+		case <-srvState.HasErr:
+			return "", srvState.Error
+		}
 	} else {
 		select {
-		case <-addr.HasAddr:
+		case <-srvState.HasAddr:
 		case <-time.After(30 * time.Second):
 			return "", errors.New("timeout waiting for Python server to start")
+		case <-srvState.HasErr:
+			return "", srvState.Error
 		}
 	}
-	conn, err := grpc.NewClient(addr.Address, grpc.WithTransportCredentials(insecure.NewCredentials()))
+	conn, err := grpc.NewClient(srvState.Address, grpc.WithTransportCredentials(insecure.NewCredentials()))
 	if err != nil {
 		return "", fmt.Errorf("failed to connect to Python server: %w", err)
 	}

cmd/klotho/main.go

@@ -27,8 +27,9 @@ func cli() int {
 	}()
 
 	var rootCmd = &cobra.Command{
-		Use:          "app",
-		SilenceUsage: true,
+		Use:           "app",
+		SilenceUsage:  true,
+		SilenceErrors: true,
 	}
 
 	rootCmd.PersistentPreRun = func(cmd *cobra.Command, args []string) {

pkg/k2/language_host/ir_service.go

@@ -26,24 +26,30 @@ func (irs *LanguageHost) Start(ctx context.Context, debug DebugConfig, pythonPat
 
 	irs.debugCfg = debug
 
-	var addr *ServerAddress
-	irs.langHost, addr, err = StartPythonClient(ctx, debug, pythonPath)
+	var srvState *ServerState
+	irs.langHost, srvState, err = StartPythonClient(ctx, debug, pythonPath)
 	if err != nil {
 		return
 	}
 	log.Debug("Waiting for Python server to start")
 	if debug.Enabled() {
 		// Don't add a timeout in case there are breakpoints in the language host before an address is printed
-		<-addr.HasAddr
+		select {
+		case <-srvState.HasAddr:
+		case <-srvState.HasErr:
+			return srvState.Error
+		}
 	} else {
 		select {
-		case <-addr.HasAddr:
+		case <-srvState.HasAddr:
 		case <-time.After(30 * time.Second):
 			return errors.New("timeout waiting for Python server to start")
+		case <-srvState.HasErr:
+			return srvState.Error
 		}
 	}
 
-	irs.conn, err = grpc.NewClient(addr.Address, grpc.WithTransportCredentials(insecure.NewCredentials()))
+	irs.conn, err = grpc.NewClient(srvState.Address, grpc.WithTransportCredentials(insecure.NewCredentials()))
 	if err != nil {
 		return fmt.Errorf("failed to connect to Python server: %w", err)
 	}

pkg/k2/language_host/language_host.go

@@ -3,11 +3,13 @@ package language_host
 import (
 	"context"
 	_ "embed"
+	"errors"
 	"fmt"
 	"io"
 	"os"
 	"os/exec"
 	"regexp"
+	"strings"
 	"syscall"
 
 	"github.com/klothoplatform/klotho/pkg/command"
@@ -19,15 +21,26 @@ import (
 //go:embed python/python_language_host.py
 var pythonLanguageHost string
 
-type ServerAddress struct {
+type ServerState struct {
 	Log     *zap.SugaredLogger
 	Address string
+	Error   error
+	HasErr  chan error
 	HasAddr chan struct{}
 }
 
+func NewServerState(log *zap.SugaredLogger) *ServerState {
+	return &ServerState{
+		Log:     log,
+		HasErr:  make(chan error),
+		HasAddr: make(chan struct{}),
+	}
+}
+
 var listenOnPattern = regexp.MustCompile(`(?m)^\s*Listening on (\S+)$`)
+var exceptionPattern = regexp.MustCompile(`(?s)(?:^|\n)\s*Exception occurred: (.+)$`)
 
-func (f *ServerAddress) Write(b []byte) (int, error) {
+func (f *ServerState) Write(b []byte) (int, error) {
 	if f.Address != "" {
 		return len(b), nil
 	}
@@ -39,6 +52,12 @@ func (f *ServerAddress) Write(b []byte) (int, error) {
 		f.Log.Debugf("Found language host listening on %s", f.Address)
 		close(f.HasAddr)
 	}
+	matches = exceptionPattern.FindStringSubmatch(s)
+	if len(matches) >= 2 {
+		f.Error = errors.New(strings.TrimSpace(matches[1]))
+		close(f.HasErr)
+		close(f.HasAddr)
+	}
 
 	return len(b), nil
 }
@@ -66,7 +85,7 @@ func copyToTempDir(name, content string) (string, error) {
 
 }
 
-func StartPythonClient(ctx context.Context, debugConfig DebugConfig, pythonPath string) (*exec.Cmd, *ServerAddress, error) {
+func StartPythonClient(ctx context.Context, debugConfig DebugConfig, pythonPath string) (*exec.Cmd, *ServerState, error) {
 	log := logging.GetLogger(ctx).Sugar()
 	hostPath, err := copyToTempDir("python_language_host", pythonLanguageHost)
 	if err != nil {
@@ -97,10 +116,7 @@ func StartPythonClient(ctx context.Context, debugConfig DebugConfig, pythonPath
 	}
 	cmd.Env = append(cmd.Env, "PYTHONPATH="+pythonPath)
 
-	lf := &ServerAddress{
-		Log:     log,
-		HasAddr: make(chan struct{}),
-	}
+	lf := NewServerState(log)
 	cmd.Stdout = io.MultiWriter(cmd.Stdout, lf)
 	command.SetProcAttr(cmd)
 

pkg/k2/language_host/python/python_language_host.py

@@ -4,18 +4,38 @@
 from concurrent import futures
 from enum import Enum
 from time import sleep
+import importlib.util
+from typing import Optional
 
 import grpc
 import yaml
-from klotho import service_pb2, service_pb2_grpc
-from klotho.runtime import instance as runtime
-
 
 class DebugMode(Enum):
     NONE = 0
     VSCODE = 1
     INTELLIJ = 2
 
+class CLIErrorReporter:
+    def __init__(self, error_message: Optional[str] = None):
+        self.error_message = error_message
+    def __enter__(self):
+        pass
+
+    def __exit__(self, exc_type, exc_value, traceback):
+        message = self.error_message if self.error_message else (f"Exception occurred: {exc_type.__name__}: {exc_value}" if exc_type is not None else "The language host exited unexpectedly.")
+        if exc_type is not None:
+            print(f"Exception occurred: {message}", flush=True)
+
+with CLIErrorReporter("The Klotho Python IaC SDK is not installed. Please install it by running `pipenv install klotho`."):
+    spec = importlib.util.find_spec("klotho")
+    if spec is None:
+        raise ModuleNotFoundError
+
+with CLIErrorReporter("The Klotho Python IaC SDK could not be imported. Please check the installation."):
+    # TODO: Add a check for the minimum required version of the SDK
+    from klotho import service_pb2, service_pb2_grpc
+    from klotho.runtime import instance as runtime
+
 
 def configure_debugging(port: int, mode: DebugMode = DebugMode.VSCODE):
     if mode == DebugMode.VSCODE:
@@ -113,4 +133,5 @@ def signal_handler(sig, frame):
 
 
 if __name__ == "__main__":
-    cli()
+    with CLIErrorReporter("The Python language host exited unexpectedly."):
+        cli()

pkg/tui/log_core.go

@@ -47,7 +47,7 @@ func (c *LogCore) With(f []zapcore.Field) zapcore.Core {
 			if c.verbosity.CombineLogs() {
 				field.AddTo(nc.enc)
 			}
-			// else (if the field is the construct and we're not combining logs) don't add it to the encoder
+			// else (if the field is the construct and we're not combining errors) don't add it to the encoder
 			// because the log lines will already be in its own construct section of the output.
 		} else {
 			field.AddTo(nc.enc)
@@ -93,6 +93,14 @@ func (c *LogCore) Write(ent zapcore.Entry, fields []zapcore.Field) error {
 	s := buf.String()
 	s = strings.TrimSuffix(s, "\n")
 
+	if c.construct == "" && zapcore.ErrorLevel.Enabled(ent.Level) {
+		c.program.Send(ErrorMessage{
+			Message: s,
+		})
+		buf.Free()
+		return nil
+	}
+
 	c.program.Send(LogMessage{
 		Construct: construct,
 		Message:   s,

pkg/tui/model.go

@@ -23,6 +23,7 @@ type (
 		consoleWidth   int
 		constructWidth int
 		statusWidth    int
+		errors         []string
 	}
 
 	constructModel struct {
@@ -81,7 +82,8 @@ func (m *model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 			cm := m.constructModel(msg.Construct)
 			cm.logs.Push(msg.Message)
 		}
-
+	case ErrorMessage:
+		m.errors = append(m.errors, msg.Message)
 	case UpdateMessage:
 		cm := m.constructModel(msg.Construct)
 
@@ -195,6 +197,10 @@ func (m *model) viewCompact() string {
 			}
 		}
 	}
+	for _, log := range m.errors {
+		sb.WriteString(log)
+		sb.WriteRune('\n')
+	}
 	return sb.String()
 }
 

pkg/tui/program.go

@@ -27,6 +27,10 @@ type (
 		Value     any
 	}
 
+	ErrorMessage struct {
+		Message string
+	}
+
 	TuiProgress struct {
 		Prog      *tea.Program
 		Construct string

pkg/tui/verbosity.go

@@ -27,14 +27,8 @@ func (v Verbosity) LogLevel() zapcore.Level {
 	}
 }
 
-// CombineLogs controls whether to show all logs comingled in the TUI. In other words,
-// sorted by timestamp, not grouped by construct.
+// CombineLogs controls whether to show all errors commingled in the TUI.
+// In other words, sorted by timestamp, not grouped by construct.
 func (v Verbosity) CombineLogs() bool {
-	switch v {
-	case VerbosityConcise, VerbosityDebugMore:
-		return true
-
-	default:
-		return false
-	}
+	return VerbosityDebugMore == v
 }