add in-built logging support for a better dev experience

vendor/github.com/aybabtme/humanlog/scanner.go

@@ -0,0 +1,68 @@
+package humanlog
+
+import (
+	"bufio"
+	"bytes"
+	"io"
+)
+
+var (
+	eol = [...]byte{'\n'}
+)
+
+// Scanner reads logfmt'd lines from src and prettify them onto dst.
+// If the lines aren't logfmt, it will simply write them out with no
+// prettification.
+func Scanner(src io.Reader, dst io.Writer, opts *HandlerOptions) error {
+	in := bufio.NewScanner(src)
+	in.Split(bufio.ScanLines)
+
+	var line uint64
+
+	var lastLogfmt bool
+	var lastJSON bool
+
+	logfmtEntry := LogfmtHandler{Opts: opts}
+	jsonEntry := JSONHandler{Opts: opts}
+
+	for in.Scan() {
+		line++
+		lineData := in.Bytes()
+
+		// remove that pesky syslog crap
+		lineData = bytes.TrimPrefix(lineData, []byte("@cee: "))
+
+		switch {
+
+		case jsonEntry.TryHandle(lineData):
+			dst.Write(jsonEntry.Prettify(opts.SkipUnchanged && lastJSON))
+			lastJSON = true
+
+		case logfmtEntry.TryHandle(lineData):
+			dst.Write(logfmtEntry.Prettify(opts.SkipUnchanged && lastLogfmt))
+			lastLogfmt = true
+
+		case tryDockerComposePrefix(lineData, &jsonEntry):
+			dst.Write(jsonEntry.Prettify(opts.SkipUnchanged && lastJSON))
+			lastJSON = true
+
+		case tryDockerComposePrefix(lineData, &logfmtEntry):
+			dst.Write(logfmtEntry.Prettify(opts.SkipUnchanged && lastLogfmt))
+			lastLogfmt = true
+
+		default:
+			lastLogfmt = false
+			lastJSON = false
+			dst.Write(lineData)
+		}
+		dst.Write(eol[:])
+
+	}
+
+	switch err := in.Err(); err {
+	case nil, io.EOF:
+		return nil
+	default:
+		return err
+	}
+}