fix(logspout): use custom log format

Go's syslog package hardcodes a lot of the log message format. This
is very difficult to customize for our own use. For example, we want
to follow a different timestamp format than RFC3339. We also want to
remove the hostname from the logs since we don't want users to "know"
where each container is being run from in the logs. In our case, though,
the hostname is the container ID for deis-logspout on that host which is
useless for the user, anyways. Connecting to the syslog server directly
allows us to format the message in a sensible manner.

Author: Matthew Fisher

logspout/logspout.go

@@ -2,12 +2,12 @@ package main
 
 import (
 	"fmt"
-	"io"
 	"log"
-	"log/syslog"
+	"net"
 	"net/http"
 	"net/url"
 	"os"
+	"regexp"
 	"strconv"
 	"strings"
 	"time"
@@ -62,10 +62,31 @@ func syslogStreamer(target Target, types []string, logstream chan *Log) {
 		if typestr != ",," && !strings.Contains(typestr, logline.Type) {
 			continue
 		}
-		tag := logline.Name + target.AppendTag
-		remote, err := syslog.Dial("udp", target.Addr, syslog.LOG_USER|syslog.LOG_INFO, tag)
+		tag, pid := getLogName(logline.Name)
+		conn, err := net.Dial("udp", target.Addr)
 		assert(err, "syslog")
-		io.WriteString(remote, logline.Data)
+		// HACK: Go's syslog package hardcodes the log format, so let's send our own message
+		_, err = fmt.Fprintf(conn,
+			"%s %s[%s]: %s",
+			time.Now().Format("2006-01-02 15:04:05"),
+			tag,
+			pid,
+			logline.Data)
+		assert(err, "syslog")
+	}
+}
+
+// getLogName returns a custom tag and PID for containers that
+// match Deis' specific application name format. Otherwise,
+// it returns the original name and 1 as the PID.
+func getLogName(name string) (string, string) {
+	// example regex that should match: go_v2.web.1
+	r := regexp.MustCompile(`(^[a-z0-9-]+)_(v[0-9]+)\.([a-z-_]+\.[0-9]+)$`)
+	match := r.FindStringSubmatch(name)
+	if match == nil {
+		return name, "1"
+	} else {
+		return match[1], match[3]
 	}
 }