feat: adding optional --prefix option

to ask scaph to look in PREFIX/proc and PREFIX/sys/class/powercap
instead of the default paths. This enables to run scaph in docker with
only RO mountpoins. (see discussion
#57 for more details)

src/lib.rs

@@ -31,6 +31,7 @@ fn get_sensor(matches: &ArgMatches) -> Box<dyn Sensor> {
                 .parse()
                 .unwrap(),
             matches.is_present("vm"),
+            get_argument(matches, "prefix")
         ),
         _ => PowercapRAPLSensor::new(
             get_argument(matches, "sensor-buffer-per-socket-max-kB")
@@ -40,6 +41,7 @@ fn get_sensor(matches: &ArgMatches) -> Box<dyn Sensor> {
                 .parse()
                 .unwrap(),
             matches.is_present("vm"),
+            get_argument(matches, "prefix")
         ),
     };
     Box::new(sensor)

src/main.rs

@@ -53,8 +53,17 @@ fn main() {
                 .long("vm")
                 .required(false)
                 .takes_value(false)
+        ).arg(
+            Arg::with_name("prefix")
+                .value_name("prefix")
+                .help("Ask scaphandre to look for data in a specific location instead of the default one (will look in $PREFIX/sys/class/powercap and $PREFIX/proc).")
+                .long("prefix")
+                .required(false)
+                .takes_value(false)
+                .default_value("")
         );
 
+
     for exp in res {
         let mut subcmd = SubCommand::with_name(exp).about(
             match exp {

src/sensors/mod.rs

@@ -1090,14 +1090,14 @@ mod tests {
 
     #[test]
     fn read_topology_stats() {
-        let mut sensor = powercap_rapl::PowercapRAPLSensor::new(8, 8, false);
+        let mut sensor = powercap_rapl::PowercapRAPLSensor::new(8, 8, false, String::from(""));
         let topo = (*sensor.get_topology()).unwrap();
         println!("{:?}", topo.read_stats());
     }
 
     #[test]
     fn read_core_stats() {
-        let mut sensor = powercap_rapl::PowercapRAPLSensor::new(8, 8, false);
+        let mut sensor = powercap_rapl::PowercapRAPLSensor::new(8, 8, false, String::from(""));
         let mut topo = (*sensor.get_topology()).unwrap();
         for s in topo.get_sockets() {
             for c in s.get_cores() {
@@ -1108,7 +1108,7 @@ mod tests {
 
     #[test]
     fn read_socket_stats() {
-        let mut sensor = powercap_rapl::PowercapRAPLSensor::new(8, 8, false);
+        let mut sensor = powercap_rapl::PowercapRAPLSensor::new(8, 8, false, String::from(""));
         let mut topo = (*sensor.get_topology()).unwrap();
         for s in topo.get_sockets() {
             println!("{:?}", s.read_stats());

src/sensors/powercap_rapl.rs

@@ -21,8 +21,9 @@ impl PowercapRAPLSensor {
         buffer_per_socket_max_kbytes: u16,
         buffer_per_domain_max_kbytes: u16,
         virtual_machine: bool,
+        prefix: String
     ) -> PowercapRAPLSensor {
-        let mut powercap_path = String::from("/sys/class/powercap");
+        let mut powercap_path = String::from(format!("{}/sys/class/powercap", prefix));
         if virtual_machine {
             powercap_path = String::from("/var/scaphandre");
             if let Ok(val) = env::var("SCAPHANDRE_POWERCAP_PATH") {
@@ -127,7 +128,7 @@ mod tests {
     }
     #[test]
     fn get_topology_returns_topology_type() {
-        let mut sensor = PowercapRAPLSensor::new(1, 1, false);
+        let mut sensor = PowercapRAPLSensor::new(1, 1, false, String::from(""));
         let topology = sensor.get_topology();
         assert_eq!(
             "alloc::boxed::Box<core::option::Option<scaphandre::sensors::Topology>>",

tests/integration.rs

@@ -5,7 +5,7 @@ use std::fs::{create_dir, read_dir};
 
 #[test]
 fn exporter_qemu() {
-    let sensor = PowercapRAPLSensor::new(1, 1, false);
+    let sensor = PowercapRAPLSensor::new(1, 1, false, String::from(""));
     let mut exporter = QemuExporter::new(Box::new(sensor));
     // Create integration_tests directory if it does not exist
     let curdir = current_dir().unwrap();