Allow listening on arbitrary IPv4/IPv6 addresses

Author: GrantFleming

README.md

@@ -55,6 +55,7 @@ Usage: fdbexporter [OPTIONS]
 
 Options:
   -p, --port <PORT>            Listening port of the web server [env: FDB_EXPORTER_PORT=] [default: 9090]
+  -a, --addr                   Listening IPv4/IPv6 address of the web server [env: FDB_EXPORTER_ADDR=] [default: 0.0.0.0]
   -c, --cluster <CLUSTER>      Location of fdb.cluster file [env: FDB_CLUSTER_FILE=]
   -d, --delay-sec <DELAY_SEC>  Delay in seconds between two update of the status & metrics [env: FDB_EXPORTER_DELAY=] [default: 15]
   -h, --help                   Print help

src/main.rs

@@ -9,7 +9,7 @@ use hyper_util::rt::TokioIo;
 use prometheus::{Encoder, TextEncoder};
 
 use std::convert::Infallible;
-use std::net::SocketAddr;
+use std::net::{IpAddr, SocketAddr};
 use std::num::ParseIntError;
 use std::path::PathBuf;
 
@@ -28,7 +28,7 @@ async fn metrics(_: Request<impl hyper::body::Body>) -> Result<Response<Full<Byt
 }
 
 async fn run_http_server(config: &CommandArgs) -> Result<(), anyhow::Error> {
-    let addr: SocketAddr = ([0, 0, 0, 0], config.port).into();
+    let addr: SocketAddr = (config.addr, config.port).into();
     let listener = TcpListener::bind(addr).await?;
     info!("Listening on http://{}", addr);
     loop {
@@ -72,6 +72,10 @@ struct CommandArgs {
     #[arg(short, long, default_value_t = 9090, env = "FDB_EXPORTER_PORT")]
     port: u16,
 
+    /// Listen address of the web server, can be IPv4 or IPv6
+    #[arg(short, long, default_value = "0.0.0.0", env = "FDB_EXPORTER_ADDR")]
+    addr: IpAddr,
+
     /// Location of fdb.cluster file
     #[arg(short, long, env = "FDB_CLUSTER_FILE")]
     cluster: Option<PathBuf>,
@@ -117,14 +121,15 @@ pub async fn main() -> Result<(), Box<dyn std::error::Error + Send + Sync>> {
 
 #[cfg(test)]
 mod tests {
-    use std::time::Duration;
+    use std::{net::Ipv4Addr, time::Duration};
 
     use crate::CommandArgs;
 
     impl Default for CommandArgs {
         fn default() -> Self {
             CommandArgs {
                 port: 9090,
+                addr: std::net::IpAddr::V4(Ipv4Addr::new(0, 0, 0, 0)),
                 cluster: None,
                 delay_sec: Duration::from_secs(1),
             }