neon_local: background_process: launch all processes in repo dir (or datadir)

control_plane/src/background_process.rs

@@ -69,6 +69,9 @@ where
     // Not generic AsRef<OsStr>, otherwise empty `envs` prevents type inference
     EI: IntoIterator<Item = (String, String)>,
 {
+    if !datadir.metadata().context("stat datadir")?.is_dir() {
+        anyhow::bail!("`datadir` must be a directory when calling this function: {datadir:?}");
+    }
     let log_path = datadir.join(format!("{process_name}.log"));
     let process_log_file = fs::OpenOptions::new()
         .create(true)
@@ -85,7 +88,13 @@ where
     let background_command = command
         .stdout(process_log_file)
         .stderr(same_file_for_stderr)
-        .args(args);
+        .args(args)
+        // spawn all child processes in their datadir, useful for all kinds of things,
+        // not least cleaning up child processes e.g. after an unclean exit from the test suite:
+        // ```
+        // lsof  -d cwd -a +D  Users/cs/src/neon/test_output
+        // ```
+        .current_dir(datadir);
 
     let filled_cmd = fill_env_vars_prefixed_neon(fill_remote_storage_secrets_vars(
         fill_rust_env_vars(background_command),

control_plane/src/local_env.rs

@@ -42,8 +42,8 @@ pub struct LocalEnv {
     // compute endpoints).
     //
     // This is not stored in the config file. Rather, this is the path where the
-    // config file itself is. It is read from the NEON_REPO_DIR env variable or
-    // '.neon' if not given.
+    // config file itself is. It is read from the NEON_REPO_DIR env variable which
+    // must be an absolute path. If the env var is not set, $PWD/.neon is used.
     pub base_data_dir: PathBuf,
 
     // Path to postgres distribution. It's expected that "bin", "include",
@@ -719,10 +719,25 @@ impl LocalEnv {
 }
 
 pub fn base_path() -> PathBuf {
-    match std::env::var_os("NEON_REPO_DIR") {
-        Some(val) => PathBuf::from(val),
-        None => PathBuf::from(".neon"),
-    }
+    let path = match std::env::var_os("NEON_REPO_DIR") {
+        Some(val) => {
+            let path = PathBuf::from(val);
+            if !path.is_absolute() {
+                // repeat the env var in the error because our default is always absolute
+                panic!("NEON_REPO_DIR must be an absolute path, got {path:?}");
+            }
+            path
+        }
+        None => {
+            let pwd = std::env::current_dir()
+                // technically this can fail but it's quite unlikeley
+                .expect("determine current directory");
+            let pwd_abs = pwd.canonicalize().expect("canonicalize current directory");
+            pwd_abs.join(".neon")
+        }
+    };
+    assert!(path.is_absolute());
+    path
 }
 
 /// Generate a public/private key pair for JWT authentication

control_plane/src/storage_controller.rs

@@ -318,10 +318,7 @@ impl StorageController {
             &self.env.base_data_dir,
             &self.env.storage_controller_bin(),
             args,
-            [(
-                "NEON_REPO_DIR".to_string(),
-                self.env.base_data_dir.to_string_lossy().to_string(),
-            )],
+            [],
             background_process::InitialPidFile::Create(self.pid_file()),
             || async {
                 match self.ready().await {