add reload support to api daemon

Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com>

src/bin/proxmox-backup-api.rs

@@ -4,6 +4,7 @@ extern crate proxmox_backup;
 use proxmox_backup::api_schema::router::*;
 use proxmox_backup::api_schema::config::*;
 use proxmox_backup::server::rest::*;
+use proxmox_backup::tools::daemon::ReexecStore;
 use proxmox_backup::auth_helpers::*;
 use proxmox_backup::config;
 
@@ -11,9 +12,12 @@ use failure::*;
 use lazy_static::lazy_static;
 
 use futures::future::Future;
+use tokio::prelude::*;
 
 use hyper;
 
+static mut QUIT_MAIN: bool = false;
+
 fn main() {
 
     if let Err(err) = run() {
@@ -23,6 +27,8 @@ fn main() {
 }
 
 fn run() -> Result<(), Error> {
+    // This manages data for reloads:
+    let mut reexecer = ReexecStore::new();
 
     if let Err(err) = syslog::init(
         syslog::Facility::LOG_DAEMON,
@@ -43,8 +49,6 @@ fn run() -> Result<(), Error> {
     }
     let _ = csrf_secret(); // load with lazy_static
 
-    let addr = ([127,0,0,1], 82).into();
-
     lazy_static!{
        static ref ROUTER: Router = proxmox_backup::api2::router();
     }
@@ -54,12 +58,76 @@ fn run() -> Result<(), Error> {
 
     let rest_server = RestServer::new(config);
 
-    let server = hyper::Server::bind(&addr)
+    // http server future:
+
+    let listener: tokio::net::TcpListener = reexecer.restore(
+        "PROXMOX_BACKUP_LISTEN_FD",
+        || {
+            let addr = ([127,0,0,1], 82).into();
+            Ok(tokio::net::TcpListener::bind(&addr)?)
+        },
+    )?;
+
+    let mut http_server = hyper::Server::builder(listener.incoming())
         .serve(rest_server)
         .map_err(|e| eprintln!("server error: {}", e));
 
-    // Run this server for... forever!
-    hyper::rt::run(server);
+    // signalfd future:
+
+    let signal_handler =
+        proxmox_backup::tools::daemon::default_signalfd_stream(
+            reexecer,
+            || {
+                unsafe { QUIT_MAIN = true; }
+                Ok(())
+            },
+        )?
+        .map(|si| {
+            // debugging...
+            eprintln!("received signal: {}", si.ssi_signo);
+        })
+        .map_err(|e| {
+            eprintln!("error from signalfd: {}, shutting down...", e);
+            unsafe {
+                QUIT_MAIN = true;
+            }
+        });
+
+
+    // Combined future for signalfd & http server, we want to quit as soon as either of them ends.
+    // Neither of them is supposed to end unless some weird error happens, so just bail out if is
+    // the case...
+    let mut signal_handler = signal_handler.into_future();
+    let main = futures::future::poll_fn(move || {
+        // Helper for some diagnostic error messages:
+        fn poll_helper<S: Future>(stream: &mut S, name: &'static str) -> bool {
+            match stream.poll() {
+                Ok(Async::Ready(_)) => {
+                    eprintln!("{} ended, shutting down", name);
+                    true
+                }
+                Err(_) => {
+                    eprintln!("{} error, shutting down", name);
+                    true
+                },
+                _ => false,
+            }
+        }
+        if poll_helper(&mut http_server, "http server") ||
+           poll_helper(&mut signal_handler, "signalfd handler")
+        {
+            return Ok(Async::Ready(()));
+        }
+
+        if unsafe { QUIT_MAIN } {
+            eprintln!("shutdown requested");
+            Ok(Async::Ready(()))
+        } else {
+            Ok(Async::NotReady)
+        }
+    });
+
+    hyper::rt::run(main);
 
     Ok(())
 }