Only rebuild Docker images when their source has been modified

tests/docker/Cargo.toml

@@ -12,3 +12,6 @@ publish = false
 [package.metadata.docs.rs]
 all-features = true
 rustdoc-args = ["--cfg", "docsrs"]
+
+[dependencies]
+chrono = "0.4"

tests/docker/src/lib.rs

@@ -1,7 +1,10 @@
 use std::{
   sync::{Mutex, OnceLock},
-  collections::HashMap,
-  env,
+  collections::{HashSet, HashMap},
+  time::SystemTime,
+  path::PathBuf,
+  fs, env,
+  process::Command,
 };
 
 static BUILT: OnceLock<Mutex<HashMap<String, bool>>> = OnceLock::new();
@@ -15,20 +18,101 @@ pub fn build(name: String) {
   }
 
   // Else, hold the lock while we build
-  let mut path = env::current_exe().unwrap();
-  path.pop();
-  assert!(path.as_path().ends_with("deps"));
-  path.pop();
-  assert!(path.as_path().ends_with("debug"));
-  path.pop();
-  assert!(path.as_path().ends_with("target"));
-  path.pop();
-  path.push("deploy");
+  let mut repo_path = env::current_exe().unwrap();
+  repo_path.pop();
+  assert!(repo_path.as_path().ends_with("deps"));
+  repo_path.pop();
+  assert!(repo_path.as_path().ends_with("debug"));
+  repo_path.pop();
+  assert!(repo_path.as_path().ends_with("target"));
+  repo_path.pop();
+
+  let mut deploy_path = repo_path.clone();
+  deploy_path.push("deploy");
+
+  // If this Docker image was created after this repo was last edited, return here
+  // This should have better performance than Docker and allows running while offline
+  if let Ok(res) = Command::new("docker")
+    .arg("inspect")
+    .arg("-f")
+    .arg("{{ .Metadata.LastTagTime }}")
+    .arg(format!("serai-dev-{name}"))
+    .output()
+  {
+    let created_time = SystemTime::from(
+      chrono::DateTime::parse_and_remainder(
+        String::from_utf8(res.stdout).expect("docker had non-utf8 output").trim(),
+        "%F %T.%f %z",
+      )
+      .expect("docker formatted last tag time unexpectedly")
+      .0,
+    );
+
+    let mut dockerfile_path = repo_path.join("deploy");
+    if HashSet::from(["bitcoin", "ethereum", "monero"]).contains(name.as_str()) {
+      dockerfile_path = dockerfile_path.join("coins");
+    }
+    dockerfile_path = dockerfile_path.join(&name).join("Dockerfile");
+
+    // For all services, if the Dockerfile was edited after the image was built we should rebuild
+    let mut last_modified =
+      fs::metadata(dockerfile_path).ok().and_then(|meta| meta.modified().ok());
+
+    // Check any additionally specified paths
+    let meta = |path: PathBuf| (path.clone(), fs::metadata(path));
+    let mut metadatas = match name.as_str() {
+      "bitcoin" => vec![],
+      "monero" => vec![],
+      "message-queue" => vec![
+        meta(repo_path.join("common")),
+        meta(repo_path.join("crypto")),
+        meta(repo_path.join("substrate").join("primitives")),
+        meta(repo_path.join("message-queue")),
+      ],
+      "processor" => vec![
+        meta(repo_path.join("common")),
+        meta(repo_path.join("crypto")),
+        meta(repo_path.join("coins")),
+        meta(repo_path.join("substrate")),
+        meta(repo_path.join("message-queue")),
+        meta(repo_path.join("processor")),
+      ],
+      _ => panic!("building unrecognized docker image"),
+    };
+
+    while !metadatas.is_empty() {
+      if let (path, Ok(metadata)) = metadatas.pop().unwrap() {
+        if metadata.is_file() {
+          if let Ok(modified) = metadata.modified() {
+            if modified >
+              last_modified
+                .expect("got when source was last modified yet not when the Dockerfile was")
+            {
+              last_modified = Some(modified);
+            }
+          }
+        } else {
+          for entry in fs::read_dir(path.clone()).expect("couldn't read directory") {
+            metadatas
+              .push(meta(path.join(entry.expect("couldn't access item in directory").file_name())));
+          }
+        }
+      }
+    }
+
+    if let Some(last_modified) = last_modified {
+      if last_modified < created_time {
+        println!("{} was built after the most recent source code edits, assuming built.", name);
+        built_lock.insert(name, true);
+        return;
+      }
+    }
+  }
 
   println!("Building {}...", &name);
 
-  assert!(std::process::Command::new("docker")
-    .current_dir(path)
+  assert!(Command::new("docker")
+    .current_dir(deploy_path)
     .arg("compose")
     .arg("build")
     .arg(&name)