Fix SIGTERM signal handling for clean docker container shutdowns

Dockerfile

@@ -1,5 +1,7 @@
 FROM node:18-alpine
 
+RUN apk add jq
+
 COPY /docker /scripts
 
 COPY /functions /functions

docker/start.sh

@@ -4,4 +4,10 @@ set -eu -o pipefail
 /scripts/package-restore.sh
 
 cd /functions
-exec npm start
+
+# Read the npm start script from package.json then exec it to ensure that
+# it is the root process in the container, so that signals (ie SIGTERM)
+# are propagated properly. "npm start" does not propagate SIGTERM to the
+# actual started process
+START_CMD=$(jq -r ".scripts.start" "package.json")
+PATH=$PATH:/functions/node_modules/.bin exec $START_CMD

ndc-lambda-sdk/bin/index.js

@@ -35,6 +35,7 @@ const [command, args] =
     ? ["ts-node-dev", ["--respawn", ...tsNodeArgs]]
     : ["ts-node", tsNodeArgs]
 
-const result = spawn.sync(command, args, { stdio: "inherit" })
-if (result.error) console.error(result.error);
-process.exit(result.status ?? undefined);
+const childProcess = spawn(command, args, { stdio: "inherit" })
+process.on("SIGTERM", () => childProcess.kill("SIGTERM"));
+childProcess.on("error", err => console.error(err));
+childProcess.on("close", code => process.exit(code));