⚡ Make terraform deploy forward abort to terraform

CHANGELOG.md

@@ -6,6 +6,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Fixed
+- Terraform deploy now sends sigint to terraform on ctrl+C, giving it a chance
+  to shut down a little more gracefully.
+
 ## [4.1.0] - 2024-02-16
 
 ### Added

flake.nix

@@ -85,4 +85,3 @@
         }
       );
 }
-

terraform/deployment/deployer.nix

@@ -2,6 +2,6 @@
 python3.pkgs.buildPythonApplication
 {
   name = "terraform-deployer";
-  version = "2.0.0";
+  version = "2.0.1";
   src = ./.;
 }

terraform/deployment/terraform.py

@@ -6,10 +6,15 @@
 import os
 import pathlib
 import shutil
+import signal
 import subprocess
 import sys
+import time
+import types
 import typing
 
+"""Have we received an abort signal (SIGINT/SIGTERM)?"""
+abort_requested: bool = False
 
 def _setup_sources(source: pathlib.Path) -> None:
     shutil.copytree(src=source, dst=os.getcwd(), dirs_exist_ok=True)
@@ -19,10 +24,36 @@ def _setup_sources(source: pathlib.Path) -> None:
             os.chmod(path=os.path.join(root, content), mode=0o755)
 
 
+def _handle_termination(signum: int, frame: typing.Optional[types.FrameType]):
+    # Make sure we always wait for terraform to exit
+    # so it can remove lock files and exit cleanly.
+    print(f"Abort requested ({signal.strsignal(signum)}).")
+    global abort_requested
+    abort_requested = True
+
+
 def _run_terraform(command: str, args: typing.List[str] = None) -> None:
-    subprocess.check_call(
-        ["terraform", command, "-lock-timeout=300s", "-input=false"] + (args or []),
-    )
+    global abort_requested
+    if abort_requested:
+        raise subprocess.CalledProcessError(1, "did-not-start-terraform")
+
+    aborted = False
+    cmd = ["terraform", command, "-lock-timeout=300s", "-input=false"] + (args or [])
+    with subprocess.Popen(cmd, start_new_session=True) as process:
+        while process.poll() is None:
+            if abort_requested:
+                os.killpg(os.getpgid(process.pid), signal.SIGINT)
+                abort_requested = False
+                aborted = True
+                print("Waiting for terraform to exit")
+
+            time.sleep(0.25)
+
+        # terraform returns 0 when aborted via SIGINT
+        if aborted:
+            raise subprocess.CalledProcessError(-signal.SIGINT, " ".join(cmd))
+        elif process.returncode != 0:
+            raise subprocess.CalledProcessError(process.returncode, " ".join(cmd))
 
 
 def apply(args: argparse.Namespace) -> None:
@@ -71,6 +102,9 @@ def main() -> None:
 
     args = parser.parse_args()
 
+    signal.signal(signal.SIGTERM, _handle_termination)
+    signal.signal(signal.SIGINT, _handle_termination)
+
     try:
         if args.subcommand is None:
             apply(args)