Added ability to override server name in prometheus metrics

README.md

@@ -22,7 +22,7 @@ docker run --net=host -it nethermindeth/nethermind:latest
 ```
 3. Run the interceptor:
 ```bash
-docker run --net="host" -e LISTEN_PORT=0.0.0.0:8081 -e SERVICE_TO_PROXY=0.0.0.0:8545 -e LOG_SERVER_URL=0.0.0.0:514 jrpc-interceptor
+docker run --net="host" -e LISTEN_PORT=0.0.0.0:8081 -e SERVICE_TO_PROXY=0.0.0.0:8545 -e LOG_SERVER_URL=0.0.0.0:514 -e SERVER_NAME="" jrpc-interceptor
 ```
 
 Where:
@@ -32,6 +32,7 @@ Where:
 - `PROMETHEUS_URL` - the IP / port of the Prometheus server. Optional, "0.0.0.0:9100" by default.
 - `USE_PROMETHEUS` - whether to publish metrics to Prometheus. Optional, "true" by default.
 - `LOG_SERVER_DEBUG` - whether to print the logs to stdout. Optional, "true" by default.
+- `SERVER_NAME` - name to use for the `server` tag in Prometheus metrics. Optional, empty by default (uses dynamic hostname from syslog messages).
 
 4. Send requests to the interceptor:
 ```bash
@@ -54,9 +55,16 @@ go build .
 ```
 3. Run the interceptor:
 ```bash
-./jrpc-interceptor -debug=${LOG_SERVER_DEBUG:-true} -listenSyslog=${LOG_SERVER_URL:-"0.0.0.0:514"} -listenHTTP=${PROMETHEUS_URL:-"0.0.0.0:9100"} -usePrometheus=${USE_PROMETHEUS:-true}
+./jrpc-interceptor -debug=${LOG_SERVER_DEBUG:-true} -listenSyslog=${LOG_SERVER_URL:-"0.0.0.0:514"} -listenHTTP=${PROMETHEUS_URL:-"0.0.0.0:9100"} -usePrometheus=${USE_PROMETHEUS:-true} -serverName=${SERVER_NAME:-""}
 ```
 
+The following command-line flags are available:
+- `-debug` - whether to print the logs to stdout. Optional, `false` by default.
+- `-listenSyslog` - the IP / port of the syslog server. Optional, `0.0.0.0:514` by default.
+- `-listenHTTP` - the IP / port of the Prometheus server. Optional, `0.0.0.0:9100` by default.
+- `-usePrometheus` - whether to publish metrics to Prometheus. Optional, `true` by default.
+- `-serverName` - name to use for the `server` tag in Prometheus metrics. When empty (default), the hostname from each syslog message is used. Set this when you want to override the default hostname with a custom name.
+
 ### Download docker image from github container registry
 
 1. Create a [personal access token ](https://github.com/settings/tokens)(PAT) on github with repo access

entrypoint.sh

@@ -1,3 +1,3 @@
 #!/bin/sh
-./jrpc-interceptor -debug=${LOG_SERVER_DEBUG:-true} -listenSyslog=${LOG_SERVER_URL:-"0.0.0.0:514"} -listenHTTP=${PROMETHEUS_URL:-"0.0.0.0:9100"} -usePrometheus=${USE_PROMETHEUS:-true}  &
-envsubst '${SERVICE_TO_PROXY} ${LOG_SERVER_URL} ${LISTEN_PORT}' < /etc/nginx/templates/nginx.conf.template > /etc/nginx/conf.d/default.conf && exec nginx -g 'daemon off;'
+./jrpc-interceptor -debug=${LOG_SERVER_DEBUG:-true} -listenSyslog=${LOG_SERVER_URL:-"0.0.0.0:514"} -listenHTTP=${PROMETHEUS_URL:-"0.0.0.0:9100"} -serverName=${SERVER_NAME:-""} -usePrometheus=${USE_PROMETHEUS:-true}  &
+envsubst '${SERVICE_TO_PROXY} ${LOG_SERVER_URL} ${LISTEN_PORT} ${SERVER_NAME}' < /etc/nginx/templates/nginx.conf.template > /etc/nginx/conf.d/default.conf && exec nginx -g 'daemon off;'

main.go

@@ -8,13 +8,14 @@ import (
 )
 
 var (
-	debug   bool
+	debug      bool
+	serverName string
 )
 
 func receiveSyslog(ch syslog.LogPartsChannel) {
 	var (
-		l       *logEntry
-		err     error
+		l   *logEntry
+		err error
 	)
 
 	for msg := range ch {
@@ -40,13 +41,14 @@ func receiveSyslog(ch syslog.LogPartsChannel) {
 
 func main() {
 	var (
-		listenSyslog   string
-		listenHTTP     string
+		listenSyslog  string
+		listenHTTP    string
 		usePrometheus bool
 	)
 
 	flag.StringVar(&listenSyslog, "listenSyslog", "0.0.0.0:514", "ip:port to listen for syslog messages")
 	flag.StringVar(&listenHTTP, "listenHTTP", "0.0.0.0:9100", "ip:port to listen for http requests")
+	flag.StringVar(&serverName, "serverName", "", "Server name to use in Prometheus metrics (leave empty for dynamic hostname)")
 	flag.BoolVar(&usePrometheus, "usePrometheus", true, "Enable posting metrics to Prometheus")
 	flag.BoolVar(&debug, "debug", false, "Enable debug")
 	flag.Parse()

parser.go

@@ -11,24 +11,23 @@ import (
 
 type logEntry struct {
 	// Tags
-	server        		string
-	scheme        		string
-	method        		string
-	hostname      		string
-	status        		string
-	protocol      		string
-	uri           		string
-	jrpc_method   		string
+	server      string
+	scheme      string
+	method      string
+	hostname    string
+	status      string
+	protocol    string
+	uri         string
+	jrpc_method string
 
 	// Fields
-	clientIP      		net.IP
-	duration    		float64
-	bytesSent   		uint64
-	bytesReceived      	uint64
-	response_duration   float64
+	clientIP          net.IP
+	duration          float64
+	bytesSent         uint64
+	bytesReceived     uint64
+	response_duration float64
 }
 
-
 func parseSyslogMessage(msg format.LogParts) (l *logEntry, err error) {
 	content := msg["content"].(string)
 
@@ -37,15 +36,21 @@ func parseSyslogMessage(msg format.LogParts) (l *logEntry, err error) {
 		return nil, fmt.Errorf("wrong number of fields in message: %s", content)
 	}
 
+	// Use custom serverName if provided, otherwise use hostname from syslog message
+	server := msg["hostname"].(string)
+	if serverName != "" {
+		server = serverName
+	}
+
 	l = &logEntry{
-		server:        msg["hostname"].(string),
-		scheme:        chunks[1],
-		hostname:      chunks[2],
-		method:        chunks[3],
-		protocol:      chunks[4],
-		uri:           strings.Split(chunks[5], "?")[0],
-		status:        chunks[6],
-		jrpc_method:   chunks[11],
+		server:      server,
+		scheme:      chunks[1],
+		hostname:    chunks[2],
+		method:      chunks[3],
+		protocol:    chunks[4],
+		uri:         strings.Split(chunks[5], "?")[0],
+		status:      chunks[6],
+		jrpc_method: chunks[11],
 	}
 
 	if l.clientIP = net.ParseIP(chunks[0]); l.clientIP == nil {
@@ -68,4 +73,4 @@ func parseSyslogMessage(msg format.LogParts) (l *logEntry, err error) {
 		return nil, fmt.Errorf("unable to parse response duration as float: %s", err)
 	}
 	return
-}
+}