Add use_sudo option to ipmi_sensor input (influxdata#6798)

Author: gescheit

plugins/inputs/ipmi_sensor/README.md

@@ -27,6 +27,11 @@ ipmitool -I lan -H SERVER -U USERID -P PASSW0RD sdr
   ## optionally specify the path to the ipmitool executable
   # path = "/usr/bin/ipmitool"
   ##
+  ## Setting 'use_sudo' to true will make use of sudo to run ipmitool.
+  ## Sudo must be configured to allow the telegraf user to run ipmitool
+  ## without a password.
+  # use_sudo = false
+  ##
   ## optionally force session privilege level. Can be CALLBACK, USER, OPERATOR, ADMINISTRATOR
   # privilege = "ADMINISTRATOR"
   ##
@@ -86,6 +91,21 @@ ipmi device node.  When using udev you can create the device node giving
 ```
 KERNEL=="ipmi*", MODE="660", GROUP="telegraf"
 ```
+Alternatively, it is possible to use sudo. You will need the following in your telegraf config:
+```toml
+[[inputs.ipmi_sensor]]
+  use_sudo = true
+```
+
+You will also need to update your sudoers file:
+
+```bash
+$ visudo
+# Add the following line:
+Cmnd_Alias IPMITOOL = /usr/bin/ipmitool *
+telegraf  ALL=(root) NOPASSWD: IPMITOOL
+Defaults!IPMITOOL !logfile, !syslog, !pam_session
+```
 
 ### Example Output
 

plugins/inputs/ipmi_sensor/ipmi.go

@@ -32,12 +32,18 @@ type Ipmi struct {
 	Servers       []string
 	Timeout       internal.Duration
 	MetricVersion int
+	UseSudo       bool
 }
 
 var sampleConfig = `
   ## optionally specify the path to the ipmitool executable
   # path = "/usr/bin/ipmitool"
   ##
+  ## Setting 'use_sudo' to true will make use of sudo to run ipmitool.
+  ## Sudo must be configured to allow the telegraf user to run ipmitool
+  ## without a password.
+  # use_sudo = false
+  ##
   ## optionally force session privilege level. Can be CALLBACK, USER, OPERATOR, ADMINISTRATOR
   # privilege = "ADMINISTRATOR"
   ##
@@ -112,7 +118,13 @@ func (m *Ipmi) parse(acc telegraf.Accumulator, server string) error {
 	if m.MetricVersion == 2 {
 		opts = append(opts, "elist")
 	}
-	cmd := execCommand(m.Path, opts...)
+	name := m.Path
+	if m.UseSudo {
+		// -n - avoid prompting the user for input of any kind
+		opts = append([]string{"-n", name}, opts...)
+		name = "sudo"
+	}
+	cmd := execCommand(name, opts...)
 	out, err := internal.CombinedOutputTimeout(cmd, m.Timeout.Duration)
 	timestamp := time.Now()
 	if err != nil {