diff --git a/.ci/build b/.ci/build
new file mode 100755
index 00000000..8b3c3fd6
--- /dev/null
+++ b/.ci/build
@@ -0,0 +1,7 @@
+#!/bin/bash -e
+set -Eeuo pipefail
+
+cd blastmud-repo
+echo Running tests
+cargo test --target-dir ../target --profile release-with-debug
+cargo build --target-dir ../target --profile release-with-debug
diff --git a/.concourse.yml b/.concourse.yml
index 6b4de703..6df7ea82 100644
--- a/.concourse.yml
+++ b/.concourse.yml
@@ -11,8 +11,14 @@ jobs:
           type: registry-image
           source:
             repository: rust
+        inputs:
+          - blastmud-repo
+        caches:
+          - target
+        outputs:
+          - target
         run:
-          path: echo
+          path: blastmud-repo/.ci/build
           args: ["Hello", "world!"]
 resources:
   - name: blastmud-repo
@@ -22,4 +28,3 @@ resources:
     source:
       uri: https://git.blastmud.org/blasthavers/blastmud.git
       branch: main
- 
diff --git a/Cargo.lock b/Cargo.lock
index b28465a5..62a9a460 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -188,6 +188,7 @@ dependencies = [
  "blastmud_interfaces",
  "futures",
  "log",
+ "nix",
  "once_cell",
  "rand",
  "serde",
@@ -1038,9 +1039,9 @@ dependencies = [
 
 [[package]]
 name = "nix"
-version = "0.26.1"
+version = "0.26.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "46a58d1d356c6597d08cde02c2f09d785b09e28711837b1ed667dc652c08a694"
+checksum = "bfdda3d196821d6af13126e40375cdf7da646a96114af134d5f417a9a1dc8e1a"
 dependencies = [
  "bitflags",
  "cfg-if",
diff --git a/blastmud_listener/Cargo.toml b/blastmud_listener/Cargo.toml
index 2a4606cb..af0115cb 100644
--- a/blastmud_listener/Cargo.toml
+++ b/blastmud_listener/Cargo.toml
@@ -9,6 +9,7 @@ edition = "2021"
 blastmud_interfaces = { path = "../blastmud_interfaces" }
 futures = "0.3.25"
 log = "0.4.17"
+nix = "0.26.2"
 once_cell = "1.17.0"
 rand = "0.8.5"
 serde = { version = "1.0.149", features = ["derive", "serde_derive"] }
diff --git a/blastmud_listener/src/main.rs b/blastmud_listener/src/main.rs
index a68fae31..3dd64098 100644
--- a/blastmud_listener/src/main.rs
+++ b/blastmud_listener/src/main.rs
@@ -1,4 +1,5 @@
 use std::vec::Vec;
+use std::path::Path;
 use std::collections::BTreeMap;
 use std::error::Error;
 use std::net::SocketAddr;
@@ -24,12 +25,14 @@ use warp::{
     self, filters::ws, Filter, Reply
 };
 use std::time::Instant;
+use nix::{sys::signal::{kill, Signal}, unistd::Pid};
 
 #[derive(Deserialize, Debug)]
 struct Config {
     listeners: Vec<String>,
     ws_listener: String,
     gameserver: String,
+    pidfile: String,
 }
 
 type DResult<A> = Result<A, Box<dyn Error + Send + Sync>>;
@@ -637,14 +640,51 @@ async fn start_websocket(bind: String, active_sessions: SessionMap, server_sende
     Ok(())
 }
 
+pub fn replace_old_listener(pidfile: &str) -> DResult<()> {
+    match fs::read_to_string(pidfile) {
+        Err(e) =>
+            if e.kind() == std::io::ErrorKind::NotFound {
+                info!("pidfile not found, assuming not already running");
+                Ok(())
+            } else {  
+                info!("Error reading pidfile (other than NotFound): {}", e);
+                Err(Box::new(e) as Box::<dyn Error + Send + Sync>)
+            }
+        Ok(f) => {
+            let pid: Pid = Pid::from_raw(f.parse().map_err(|e| Box::new(e) as Box::<dyn Error + Send + Sync>)?);
+            match fs::read_to_string(format!("/proc/{}/cmdline", pid)) {
+                Ok(content) =>
+                    if content.contains("blastmud_listener") {
+                        info!("pid in pidfile references blastmud_listener; starting cutover");
+                        kill(pid, Signal::SIGTERM)
+                            .map_err(|e| Box::new(e) as Box<dyn Error + Send + Sync>)
+                    } else {
+                        info!("Pid in pidfile is for process not including blastmud_listener - ignoring pidfile");
+                        Ok(())
+                    }
+                Err(_) => {
+                    info!("Pid in pidfile is gone - ignoring pidfile");
+                    Ok(())
+                }
+            }
+        }
+    }?;
+    info!("Writing new pidfile");
+    fs::write(Path::new(pidfile), format!("{}", std::process::id()))
+        .map_err(|e| Box::new(e) as Box::<dyn Error + Send + Sync>)
+}
+
+
 #[tokio::main]
 async fn main() -> Result<(), Box<dyn Error + Send + Sync>> {
     SimpleLogger::new().with_level(LevelFilter::Info).init().unwrap();
 
+
     let listener_id = Uuid::new_v4();
     let mut config = read_latest_config()?;
     let active_sessions: SessionMap =
         Arc::new(Mutex::new(SessionIndexes { by_uuid: BTreeMap::new(), count_by_source: BTreeMap::new() }));
+    replace_old_listener(&config.pidfile)?;
     let server_sender = start_server_task(listener_id, config.gameserver, active_sessions.clone());
 
     start_pinger(listener_id, server_sender.clone());
diff --git a/scripts/run-latest b/scripts/run-latest
new file mode 100644
index 00000000..75cbd101
--- /dev/null
+++ b/scripts/run-latest
@@ -0,0 +1,18 @@
+#!/bin/bash
+
+# Note: This script runs /app/exe/* at startup, and then any files moved into /app/exe/
+# (note - create files elsewhere and move them to avoid race conditions).
+# This allows deployments to work from a different Docker container by simply pushing
+# into a volume mounted in the correct place.
+# Remove the old file from /app/exe/ before moving the new one.
+# It doesn't kill off the old process, instead the new one kills the old one.
+
+for EXE in /app/exe/*; do
+    "$EXE"&
+done
+
+inotifywait --quiet --monitor -e moved_to --format "%f" /app/exe |\
+    while read MOVED
+    do
+        "/app/exe/$MOVED"&
+    done