agent: Filter messages logged to syslog. Fixes #272

command/agent/command.go

@@ -235,7 +235,7 @@ func (c *Command) setupLoggers(config *Config) (*GatedWriter, *logWriter, io.Wri
 			c.Ui.Error(fmt.Sprintf("Syslog setup failed: %v", err))
 			return nil, nil, nil
 		}
-		syslog = &SyslogWrapper{l}
+		syslog = &SyslogWrapper{l, c.logFilter}
 	}
 
 	// Create a log writer, and wrap a logOutput around it

command/agent/syslog.go

@@ -3,6 +3,7 @@ package agent
 import (
 	"bytes"
 	"github.com/hashicorp/go-syslog"
+	"github.com/hashicorp/logutils"
 )
 
 // levelPriority is used to map a log level to a
@@ -20,11 +21,17 @@ var levelPriority = map[string]gsyslog.Priority{
 // writing them to a Syslogger. Implements the io.Writer
 // interface.
 type SyslogWrapper struct {
-	l gsyslog.Syslogger
+	l    gsyslog.Syslogger
+	filt *logutils.LevelFilter
 }
 
 // Write is used to implement io.Writer
 func (s *SyslogWrapper) Write(p []byte) (int, error) {
+	// Skip syslog if the log level doesn't apply
+	if !s.filt.Check(p) {
+		return 0, nil
+	}
+
 	// Extract log level
 	var level string
 	afterLevel := p

command/agent/syslog_test.go

@@ -0,0 +1,35 @@
+package agent
+
+import (
+	"testing"
+
+	"github.com/hashicorp/go-syslog"
+	"github.com/hashicorp/logutils"
+)
+
+func TestSyslogFilter(t *testing.T) {
+	l, err := gsyslog.NewLogger(gsyslog.LOG_NOTICE, "LOCAL0", "consul")
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	filt := LevelFilter()
+	filt.MinLevel = logutils.LogLevel("INFO")
+
+	s := &SyslogWrapper{l, filt}
+	n, err := s.Write([]byte("[INFO] test"))
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+	if n == 0 {
+		t.Fatalf("should have logged")
+	}
+
+	n, err = s.Write([]byte("[DEBUG] test"))
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+	if n != 0 {
+		t.Fatalf("should not have logged")
+	}
+}