From c2b9d0e2defd04e1afb9712132a66681d077eb42 Mon Sep 17 00:00:00 2001
From: Uros Marolt <uros@marolt.me>
Date: Sat, 3 Sep 2022 13:06:22 +0200
Subject: [PATCH] CLI utility to pipe JSON logs through to pretty print and
 colorize them (#449)

---
 cmd/prettylog/README.md    | 40 ++++++++++++++++++++++++++++++++++++++
 cmd/prettylog/prettylog.go | 26 +++++++++++++++++++++++++
 2 files changed, 66 insertions(+)
 create mode 100644 cmd/prettylog/README.md
 create mode 100644 cmd/prettylog/prettylog.go

diff --git a/cmd/prettylog/README.md b/cmd/prettylog/README.md
new file mode 100644
index 0000000..2412915
--- /dev/null
+++ b/cmd/prettylog/README.md
@@ -0,0 +1,40 @@
+# Zerolog PrettyLog
+
+This is a basic CLI utility that will colorize and pretty print your structured JSON logs.
+
+## Usage
+
+You can compile it or run it directly. The only issue is that by default Zerolog does not output to `stdout`
+but rather to `stderr` so we must pipe `stderr` stream to this CLI tool.
+
+### Linux
+
+These commands will redirect `stderr` to our `prettylog` tool and `stdout` will remain unaffected.
+
+1. Compiled version
+
+```shell
+some_program_with_zerolog 2> >(prettylog)
+```
+
+2. Run it directly with `go run`
+
+```shell
+some_program_with_zerolog 2> >(go run cmd/prettylog/prettylog.go)
+```
+
+### Windows
+
+These commands will redirect `stderr` to `stdout` and then pipe it to our `prettylog` tool.
+
+1. Compiled version
+
+```shell
+some_program_with_zerolog 2>&1 | prettylog
+```
+
+2. Run it directly with `go run`
+
+```shell
+some_program_with_zerolog 2>&1 | go run cmd/prettylog/prettylog.go
+```
diff --git a/cmd/prettylog/prettylog.go b/cmd/prettylog/prettylog.go
new file mode 100644
index 0000000..61bf8b8
--- /dev/null
+++ b/cmd/prettylog/prettylog.go
@@ -0,0 +1,26 @@
+package main
+
+import (
+	"fmt"
+	"io"
+	"os"
+
+	"github.com/rs/zerolog"
+)
+
+func isInputFromPipe() bool {
+	fileInfo, _ := os.Stdin.Stat()
+	return fileInfo.Mode()&os.ModeCharDevice == 0
+}
+
+func main() {
+	if !isInputFromPipe() {
+		fmt.Println("The command is intended to work with pipes.")
+		fmt.Println("Usage: app_with_zerolog |  2> >(prettylog)")
+		os.Exit(1)
+		return
+	}
+
+	writer := zerolog.NewConsoleWriter()
+	_, _ = io.Copy(writer, os.Stdin)
+}