fn: introducing docker-syslog driver as default logger (#1189)

* fn: introducing docker-syslog driver as default logger

With this change, fn-agent prefers RFC2454 docker-syslog driver
for logging stdout/stderr from containers. The advantage
of this is to offload it to docker itself instead of
streaming stderr along with stdout, which gets multiplexed
through single connection via docker-API.

The change will need support from FDKs in order to log
correct call-id and supress '\n' that splits syslog lines.

api/agent/drivers/docker/cookie.go

@@ -25,6 +25,34 @@ type cookie struct {
 	drv *DockerDriver
 }
 
+func (c *cookie) configureLogger(log logrus.FieldLogger) {
+
+	conf := c.task.LoggerConfig()
+	if conf.URL == "" {
+		c.opts.HostConfig.LogConfig = docker.LogConfig{
+			Type: "none",
+		}
+		return
+	}
+
+	c.opts.HostConfig.LogConfig = docker.LogConfig{
+		Type: "syslog",
+		Config: map[string]string{
+			"syslog-address":  conf.URL,
+			"syslog-facility": "user",
+			"syslog-format":   "rfc5424",
+		},
+	}
+
+	tags := make([]string, 0, len(conf.Tags))
+	for _, pair := range conf.Tags {
+		tags = append(tags, fmt.Sprintf("%s=%s", pair.Name, pair.Value))
+	}
+	if len(tags) > 0 {
+		c.opts.HostConfig.LogConfig.Config["tag"] = strings.Join(tags, ",")
+	}
+}
+
 func (c *cookie) configureMem(log logrus.FieldLogger) {
 	if c.task.Memory() == 0 {
 		return

api/agent/drivers/docker/docker.go

@@ -217,15 +217,11 @@ func (drv *DockerDriver) CreateCookie(ctx context.Context, task drivers.Containe
 			Image:        task.Image(),
 			OpenStdin:    true,
 			AttachStdout: true,
-			AttachStderr: true,
 			AttachStdin:  true,
+			AttachStderr: true,
 			StdinOnce:    true,
 		},
-		// turn off logs since we're collecting them from attach
 		HostConfig: &docker.HostConfig{
-			LogConfig: docker.LogConfig{
-				Type: "none",
-			},
 			ReadonlyRootfs: drv.conf.EnableReadOnlyRootFs,
 		},
 		Context: ctx,
@@ -237,6 +233,7 @@ func (drv *DockerDriver) CreateCookie(ctx context.Context, task drivers.Containe
 		drv:  drv,
 	}
 
+	cookie.configureLogger(log)
 	cookie.configureMem(log)
 	cookie.configureCmd(log)
 	cookie.configureEnv(log)

api/agent/drivers/docker/docker_pool.go

@@ -71,6 +71,7 @@ func (c *poolTask) CPUs() uint64                                     { return 0
 func (c *poolTask) FsSize() uint64                                   { return 0 }
 func (c *poolTask) TmpFsSize() uint64                                { return 0 }
 func (c *poolTask) Extensions() map[string]string                    { return nil }
+func (c *poolTask) LoggerConfig() drivers.LoggerConfig               { return drivers.LoggerConfig{} }
 func (c *poolTask) WriteStat(ctx context.Context, stat drivers.Stat) {}
 
 type dockerPoolItem struct {

api/agent/drivers/docker/docker_test.go

@@ -37,6 +37,7 @@ func (f *taskDockerTest) WorkDir() string                         { return "" }
 func (f *taskDockerTest) Close()                                  {}
 func (f *taskDockerTest) Input() io.Reader                        { return f.input }
 func (f *taskDockerTest) Extensions() map[string]string           { return nil }
+func (f *taskDockerTest) LoggerConfig() drivers.LoggerConfig      { return drivers.LoggerConfig{} }
 
 func TestRunnerDocker(t *testing.T) {
 	dkr := NewDocker(drivers.Config{})