Disable signal handlers on AWS lambdas via env var (#462)

* Disable handle-sigint! when BABASHKA_DISABLE_PIPE_SIGNAL_HANDLER is true

This allows babashka to be run in an AWS lambda.

* Rename BABASHKA_DISABLE_PIPE_SIGNAL_HANDLER to BABASHKA_DISABLE_SIGNAL_HANDLERS

Any signal handler used in AWS lambdas will not work. This simplifies/shortens
the naming of the env var.

README.md

@@ -803,8 +803,8 @@ repo](https://github.com/babashka/babashka.pods).
 ## Package babashka script as a AWS Lambda
 
 AWS Lambda runtime doesn't support signals, therefore babashka has to disable
-handling of the SIGPIPE. This can be done by setting
-`BABASHKA_DISABLE_PIPE_SIGNAL_HANDLER` to `true`.
+handling of SIGINT and SIGPIPE. This can be done by setting
+`BABASHKA_DISABLE_SIGNAL_HANDLERS` to `true`.
 
 ## Articles, podcasts and videos
 

src/babashka/impl/pipe_signal_handler.clj

@@ -9,7 +9,7 @@
   (identical? :PIPE @pipe-state))
 
 (defn handle-pipe! []
-  (when-not (= "true" (System/getenv "BABASHKA_DISABLE_PIPE_SIGNAL_HANDLER"))
+  (when-not (= "true" (System/getenv "BABASHKA_DISABLE_SIGNAL_HANDLERS"))
     (Signal/handle
      (Signal. "PIPE")
      (reify SignalHandler

src/babashka/impl/sigint_handler.clj

@@ -6,9 +6,10 @@
 (set! *warn-on-reflection* true)
 
 (defn handle-sigint! []
-  (Signal/handle
-   (Signal. "INT")
-   (reify SignalHandler
-     (handle [_ _]
-       ;; This is needed to run shutdown hooks on interrupt, System/exit triggers those
-       (System/exit 0)))))
+  (when-not (= "true" (System/getenv "BABASHKA_DISABLE_SIGNAL_HANDLERS"))
+    (Signal/handle
+     (Signal. "INT")
+     (reify SignalHandler
+       (handle [_ _]
+         ;; This is needed to run shutdown hooks on interrupt, System/exit triggers those
+         (System/exit 0))))))