Add Syslog server to receive logs from machines during installation (#27)

Add the ability from `netbootd` to run a Syslog server on the TCP/UDP
port specified by the new `-s`/`--syslog-port` flags (defaults to
514).  A new `{{ .SyslogHost }}` value is available in mount content
templates which contains the `<host>:<port>` to send syslog messages.
This can be used, for example, to construct an
`inst.syslog=<host>:<port>` kernel argument for RHEL 9 which instructs
the installer to send syslogs to the given syslog server.  This can
make it much easier to see what is happening during an installation,
and make debugging easier in case something goes wrong.

Syslog messages received by `netbootd`'s syslog server are logged at
`INFO` level.  All syslog attributes are added to the `INFO` log
emitted by `netbootd` prepended with `syslog.`.  Thus a syslog message
with attribute `foo=bar` is emitted by `netbootd` as `syslog.foo=bar`.
The exception is `content` or `message` attributes which are used as
the value for `.Msg()`.

Author: nwidger

README.md

@@ -1,7 +1,7 @@
 # netbootd
 
 netbootd is a lightweight network boot server, designed for maximum flexibility
-and with "batteries included" approach in mind, serving as a DHCP, TFTP and HTTP server.
+and with "batteries included" approach in mind, serving as a DHCP, TFTP, Syslog and HTTP server.
 It includes a basic templating functionality, designed to allow generating e.g. preseed
 files for unattended OS installation.
 
@@ -47,6 +47,10 @@ netbootd can serve local files using the `path.localDir` configuration option.
 netbootd also contains a bundled version of [iPXE](https://ipxe.org/), which allows
 downloading (typically) kernel and initrd over HTTP instead of TFTP.
 
+## Syslog
+
+netbootd includes a syslog server to allow collecting and displaying a machine's logs during installation.
+
 ## Manifests
 
 A manifest represents a machine to be provisioned/served. The behavior of built-in DHCP, TFTP and HTTP server is
@@ -129,7 +133,7 @@ mounts:
     appendSuffix: true
 
   - path: /install.ipxe
-    # The templating context provides access to: .LocalIP, .RemoteIP, .HttpBaseUrl, .ApiBaseUrl and .Manifest.
+    # The templating context provides access to: .LocalIP, .RemoteIP, .HttpBaseUrl, .ApiBaseUrl, .SyslogHost and .Manifest.
     # Sprig functions are available: masterminds.github.io/sprig
     content: |
       #!ipxe
@@ -228,6 +232,7 @@ Flags:
   -i, --interface string      interface to listen on, e.g. eth0 (DHCP)
   -m, --manifests string      load manifests from directory
       --root string           if not given as an absolute path, a mount's path.localDir is relative to this directory
+  -s, --syslog-port int       Syslog port to listen on (default 514)
 
 Global Flags:
   -d, --debug                    enable debug logging

cmd/server.go

@@ -10,6 +10,7 @@ import (
 	"github.com/DSpeichert/netbootd/dhcpd"
 	"github.com/DSpeichert/netbootd/httpd"
 	"github.com/DSpeichert/netbootd/store"
+	"github.com/DSpeichert/netbootd/syslogd"
 	"github.com/DSpeichert/netbootd/tftpd"
 	systemd "github.com/coreos/go-systemd/v22/daemon"
 	"github.com/rs/zerolog"
@@ -22,6 +23,7 @@ var (
 	addr         string
 	ifname       string
 	httpPort     int
+	syslogPort   int
 	apiPort      int
 	apiTlsCert   string
 	apiTlsKey    string
@@ -36,6 +38,9 @@ func init() {
 	serverCmd.Flags().IntVarP(&httpPort, "http-port", "p", 8080, "HTTP port to listen on")
 	viper.BindPFlag("http.port", serverCmd.Flags().Lookup("http-port"))
 
+	serverCmd.Flags().IntVarP(&syslogPort, "syslog-port", "s", 514, "Syslog port to listen on")
+	viper.BindPFlag("syslog.port", serverCmd.Flags().Lookup("syslog-port"))
+
 	serverCmd.Flags().IntVarP(&apiPort, "api-port", "r", 8081, "HTTP API port to listen on")
 	viper.BindPFlag("api.port", serverCmd.Flags().Lookup("api-port"))
 
@@ -83,6 +88,7 @@ var serverCmd = &cobra.Command{
 			}
 		}
 		store.GlobalHints.HttpPort = viper.GetInt("http.port")
+		store.GlobalHints.SyslogPort = viper.GetInt("syslog.port")
 		store.GlobalHints.ApiPort = viper.GetInt("api.port")
 
 		// DHCP
@@ -131,6 +137,23 @@ var serverCmd = &cobra.Command{
 		go httpServer.Serve(connHttp)
 		log.Info().Interface("addr", connHttp.Addr()).Msg("HTTP listening")
 
+		// Syslog service
+		syslogServer, err := syslogd.NewServer(store)
+		if err != nil {
+			log.Fatal().Err(err).Msg("Failed to create Syslog server")
+		}
+		syslogAddr := net.JoinHostPort(addressIPStr, viper.GetString("syslog.port"))
+		err = syslogServer.ListenUDP(syslogAddr)
+		if err != nil {
+			log.Fatal().Err(err).Msg("Failed to bind UDP Syslog server")
+		}
+		err = syslogServer.ListenTCP(syslogAddr)
+		if err != nil {
+			log.Fatal().Err(err).Msg("Failed to bind TCP Syslog server")
+		}
+		go syslogServer.Serve()
+		log.Info().Interface("syslog", syslogAddr).Msg("Syslog listening...")
+
 		// HTTP API service
 		apiServer, err := api.NewServer(store, viper.GetString("api.authorization"), viper.GetString("rootPath"))
 		if err != nil {

go.mod

@@ -17,6 +17,7 @@ require (
 	github.com/u-root/uio v0.0.0-20240224005618-d2acac8f3701
 	golang.org/x/net v0.42.0
 	golang.org/x/sys v0.34.0
+	gopkg.in/mcuadros/go-syslog.v2 v2.3.0
 	gopkg.in/yaml.v2 v2.4.0
 )
 

go.sum

@@ -117,6 +117,8 @@ golang.org/x/text v0.27.0/go.mod h1:1D28KMCvyooCX9hBiosv5Tz/+YLxj0j7XhWjpSUF7CU=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c h1:Hei/4ADfdWqJk1ZMxUNpqntNwaWcugrBjAiHlqqRiVk=
 gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c/go.mod h1:JHkPIbrfpd72SG/EVd6muEfDQjcINNoR0C8j2r3qZ4Q=
+gopkg.in/mcuadros/go-syslog.v2 v2.3.0 h1:kcsiS+WsTKyIEPABJBJtoG0KkOS6yzvJ+/eZlhD79kk=
+gopkg.in/mcuadros/go-syslog.v2 v2.3.0/go.mod h1:l5LPIyOOyIdQquNg+oU6Z3524YwrcqEm0aKH+5zpt2U=
 gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
 gopkg.in/yaml.v2 v2.4.0 h1:D8xgwECY7CYvx+Y2n4sBz93Jn9JRvxdiyyo8CTfuKaY=
 gopkg.in/yaml.v2 v2.4.0/go.mod h1:RDklbk79AGWmwhnvt/jBztapEOGDOx6ZbXqjP6csGnQ=

httpd/handler.go

@@ -146,7 +146,8 @@ func (h Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 				Scheme: "http",
 				Host:   net.JoinHostPort(laddr.String(), strconv.Itoa(h.server.store.GlobalHints.ApiPort)),
 			},
-			Manifest: manifest,
+			SyslogHost: net.JoinHostPort(laddr.String(), strconv.Itoa(h.server.store.GlobalHints.SyslogPort)),
+			Manifest:   manifest,
 		})
 		if err != nil {
 			h.server.logger.Error().

manifest/schema.go

@@ -129,6 +129,8 @@ type ContentContext struct {
 	HttpBaseUrl *url.URL
 	// Base URL to the API service (IP and port)
 	ApiBaseUrl *url.URL
+	// Host to Syslog service (IP and port)
+	SyslogHost string
 	// Copy of Manifest
 	Manifest *Manifest
 }

store/store.go

@@ -36,8 +36,9 @@ type Store struct {
 
 	// sort of global config
 	GlobalHints struct {
-		HttpPort int
-		ApiPort  int
+		HttpPort   int
+		ApiPort    int
+		SyslogPort int
 	}
 }
 

syslogd/handler.go

@@ -0,0 +1,30 @@
+package syslogd
+
+import "gopkg.in/mcuadros/go-syslog.v2/format"
+
+func (server *Server) syslogHandleLog(logParts format.LogParts) {
+	event := server.logger.Info()
+	var msg string
+	for key, value := range logParts {
+		if m, ok := isMsg(key, value); ok {
+			msg = m
+			continue
+		}
+		event = event.Interface("syslog."+key, value)
+	}
+	if msg == "" {
+		msg = "UNKNOWN"
+	}
+	event.Msg(msg)
+}
+
+func isMsg(key string, value any) (m string, ok bool) {
+	if key != "content" && key != "message" {
+		return "", false
+	}
+	m, ok = value.(string)
+	if !ok {
+		return "", false
+	}
+	return m, true
+}

syslogd/server.go

@@ -0,0 +1,65 @@
+package syslogd
+
+import (
+	"github.com/DSpeichert/netbootd/store"
+	"github.com/rs/zerolog"
+	"github.com/rs/zerolog/log"
+	"gopkg.in/mcuadros/go-syslog.v2"
+)
+
+var defaultAddr = "0.0.0.0:514"
+
+type Server struct {
+	syslogServer *syslog.Server
+
+	logger zerolog.Logger
+	store  *store.Store
+	ch     syslog.LogPartsChannel
+}
+
+func NewServer(store *store.Store) (server *Server, err error) {
+	server = &Server{
+		syslogServer: syslog.NewServer(),
+		logger:       log.With().Str("service", "syslog").Logger(),
+		store:        store,
+		ch:           make(syslog.LogPartsChannel),
+	}
+
+	server.syslogServer.SetFormat(syslog.Automatic)
+	server.syslogServer.SetHandler(syslog.NewChannelHandler(server.ch))
+
+	return server, nil
+}
+
+func (server *Server) ListenUDP(addr string) error {
+	if addr == "" {
+		addr = defaultAddr
+	}
+	err := server.syslogServer.ListenUDP(addr)
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+func (server *Server) ListenTCP(addr string) error {
+	if addr == "" {
+		addr = defaultAddr
+	}
+	err := server.syslogServer.ListenTCP(addr)
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+func (server *Server) Serve() error {
+	err := server.syslogServer.Boot()
+	if err != nil {
+		return err
+	}
+	for logParts := range server.ch {
+		server.syslogHandleLog(logParts)
+	}
+	return nil
+}

tftpd/handler.go

@@ -146,7 +146,8 @@ func (server *Server) tftpReadHandler(filename string, rf io.ReaderFrom) error {
 				Scheme: "http",
 				Host:   net.JoinHostPort(laddr.String(), strconv.Itoa(server.store.GlobalHints.ApiPort)),
 			},
-			Manifest: manifest,
+			SyslogHost: net.JoinHostPort(laddr.String(), strconv.Itoa(server.store.GlobalHints.SyslogPort)),
+			Manifest:   manifest,
 		})
 		if err != nil {
 			server.logger.Error().