Merge branch 'main' into main

README.md

@@ -92,6 +92,49 @@ format.
 The `--config.file` parameter can be used multiple times to load more than one file.
 It also supports [glob filename matching](https://pkg.go.dev/path/filepath#Glob), e.g. `modbus_*.yml`.
 
+## Systemd service
+
+You can create a systemd service if you want to run modbus exporter as a service in the background. Start by creating a modbus_exporter system account (example on Debian)
+
+```shell
+useradd -r modbus_exporter
+```
+
+Place the modbus_exporter binary at `/usr/local/bin/modbus_exporter`
+
+The following example systemd unit file can be saved to `/etc/systemd/system/modbus_exporter.service`:
+
+```systemd
+[Unit]
+Description=Modbus TCP Prometheus exporter
+Requires=network.target
+After=network-online.target
+Wants=network-online.target
+
+[Service]
+User=modbus_exporter
+Group=nogroup
+ExecStart=/usr/local/bin/modbus_exporter --config.file='/etc/modbus_exporter.yml'
+Restart=on-failure
+RestartSec=1
+
+[Install]
+WantedBy=multi-user.target
+```
+
+Then locate your config file in `/etc/modbus_exporter.yml`, and run the following commands to make systemd aware of config changes and startup the modbus_exporter
+
+```shell
+systemctl daemon-reload
+systemctl start modbus_exporter
+```
+
+In order to start the service at boot, run the following
+
+```shell
+systemctl enable modbus_exporter
+```
+
 ## TODO
 
 - Rework logging.

config/config.go

@@ -15,6 +15,7 @@ package config
 
 import (
 	"fmt"
+	"time"
 
 	multierror "github.com/hashicorp/go-multierror"
 )
@@ -59,14 +60,19 @@ type ListTargets map[string]*Module
 
 // Module defines the configuration parameters of a modbus module.
 type Module struct {
-	Name     string         `yaml:"name"`
-	Protocol ModbusProtocol `yaml:"protocol"`
-	Timeout  int            `yaml:"timeout"`
-	Baudrate int            `yaml:"baudrate"`
-	Databits int            `yaml:"databits"`
-	Stopbits int            `yaml:"stopbits"`
-	Parity   string         `yaml:"parity"`
-	Metrics  []MetricDef    `yaml:"metrics"`
+	Name        string         `yaml:"name"`
+	Protocol    ModbusProtocol `yaml:"protocol"`
+	Timeout     int            `yaml:"timeout"`
+	Baudrate    int            `yaml:"baudrate"`
+	Databits    int            `yaml:"databits"`
+	Stopbits    int            `yaml:"stopbits"`
+	Parity      string         `yaml:"parity"`
+	Metrics     []MetricDef    `yaml:"metrics"`
+	Workarounds Workarounds    `yaml:"workarounds"`
+}
+
+type Workarounds struct {
+	SleepAfterConnect time.Duration `yaml:"sleepAfterConnect"`
 }
 
 // RegisterAddr specifies the register in the possible output of _digital

modbus.yml

@@ -3,6 +3,10 @@ modules:
     # Module name, needs to be passed as parameter by Prometheus.
   - name: "fake"
     protocol: 'tcp/ip'
+    # Certain modbus devices need special timing workarounds
+    workarounds:
+      # Sleep a certain time after the TCP connection is established
+      sleepAfterConnect: "1s"
     metrics:
         # Name of the metric.
       - name: "power_consumption_total"

modbus/modbus.go

@@ -63,6 +63,10 @@ func (e *Exporter) Scrape(targetAddress string, subTarget byte, moduleName strin
 			targetAddress, module.Name)
 	}
 
+	if module.Workarounds.SleepAfterConnect > 0 {
+		time.Sleep(module.Workarounds.SleepAfterConnect)
+	}
+
 	// TODO: Should we reuse this?
 	c := modbus.NewClient(handler)