add Fatal{Context}{f} (#8)

This adds `clog.Fatal{Context}{f}`, and
`clog.FromContext(ctx).Fatal{Context}{f}`

`Fatal` logs at `LevelError` then calls `os.Exit(1)`, like stdlib
`log.Fatal`:
https://cs.opensource.google/go/go/+/refs/tags/go1.21.6:src/log/log.go;l=413

---------

Signed-off-by: Jason Hall <jason@chainguard.dev>
Co-authored-by: Billy Lynch <1844673+wlynch@users.noreply.github.com>

log.go

@@ -3,6 +3,7 @@ package clog
 import (
 	"context"
 	"log/slog"
+	"os"
 )
 
 // Info calls Info on the default logger.
@@ -89,3 +90,27 @@ func Debugf(format string, args ...any) {
 func DebugContextf(ctx context.Context, format string, args ...any) {
 	wrapf(ctx, FromContext(ctx), slog.LevelDebug, format, args...)
 }
+
+// Fatal calls Error on the default logger, then exits.
+func Fatal(msg string, args ...any) {
+	wrap(context.Background(), DefaultLogger(), slog.LevelError, msg, args...)
+	os.Exit(1)
+}
+
+// FatalContext calls ErrorContext on the context logger, then exits.
+func FatalContext(ctx context.Context, msg string, args ...any) {
+	wrap(ctx, FromContext(ctx), slog.LevelError, msg, args...)
+	os.Exit(1)
+}
+
+// Fatalf calls Errorf on the default logger, then exits.
+func Fatalf(format string, args ...any) {
+	wrapf(context.Background(), DefaultLogger(), slog.LevelError, format, args...)
+	os.Exit(1)
+}
+
+// FatalContextf calls ErrorContextf on the context logger, then exits.
+func FatalContextf(ctx context.Context, format string, args ...any) {
+	wrapf(ctx, FromContext(ctx), slog.LevelError, format, args...)
+	os.Exit(1)
+}

logger.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"fmt"
 	"log/slog"
+	"os"
 	"runtime"
 	"time"
 )
@@ -86,6 +87,30 @@ func (l *Logger) DebugContextf(ctx context.Context, format string, args ...any)
 	wrapf(ctx, l, slog.LevelDebug, format, args...)
 }
 
+// Fatalf logs at LevelError with the given format and arguments, then exits.
+func (l *Logger) Fatalf(format string, args ...any) {
+	wrapf(context.Background(), l, slog.LevelError, format, args...)
+	os.Exit(1)
+}
+
+// Fatal logs at LevelError with the given message, then exits.
+func (l *Logger) Fatal(msg string, args ...any) {
+	wrap(context.Background(), l, slog.LevelError, msg, args...)
+	os.Exit(1)
+}
+
+// FatalfContextf logs at LevelError with the given context, format and arguments, then exits.
+func (l *Logger) FatalContextf(ctx context.Context, format string, args ...any) {
+	wrapf(ctx, l, slog.LevelError, format, args...)
+	os.Exit(1)
+}
+
+// FatalfContext logs at LevelError with the given context and message, then exits.
+func (l *Logger) FatalContext(ctx context.Context, msg string, args ...any) {
+	wrap(ctx, l, slog.LevelError, msg, args...)
+	os.Exit(1)
+}
+
 // Base returns the underlying [slog.Logger].
 func (l *Logger) Base() *slog.Logger {
 	return &l.Logger