Generalized signal handling

Dockerfile

@@ -12,6 +12,8 @@ RUN apt-get install -y wget
 RUN apt-get install -y git make gcc
 RUN apt-get install -y icewm
 RUN apt-get install -y x11-apps
+RUN apt-get install -y bc
+RUN apt-get install -y net-tools socat python3-numpy
 
 FROM base as build
 ADD https://github.com/TurboVNC/turbovnc/releases/download/3.1.1/turbovnc_3.1.1_amd64.deb /tmp/
@@ -24,9 +26,6 @@ RUN dpkg -i turbovnc_3.1.1_amd64.deb
 WORKDIR "/tmp/websockify"
 RUN make -j4
 
-# develop only
-RUN apt-get install -y net-tools socat python3-numpy
-
 ENV PATH=$PATH:/opt/TurboVNC/bin
 RUN	mkdir ~/.vnc/
 RUN	echo $PASSWORD | vncpasswd -f > ~/.vnc/passwd

app/app.sh

@@ -1,18 +1,33 @@
 #!/usr/bin/env bash
 set -x
 
+# Signal helper
 source /app/signals.sh
 
-signals_trap_with_arg func_trap TERM
+PID=0
+TERM_handler() {
+    SIGNAME="$1"
+    echo "Killing ${PID}"
+    echo "Signal ${SIGNAME}"
+    if [ ${PID} -ne 0 ]; then
+        ps -ef --forest
+        CHILDS=$(pgrep -P "${PID}")
+        kill -"${SIGNAME}" -"${PID}"
+        for i in $CHILDS; do
+          wait $i
+        done
+    fi
+    ps -ef --forest
+    ret=$(signal_return_val ${SIGNAME})
+    exit $ret
+}
 
+signals_trap_with_arg TERM_handler SIGTERM
 /app/server.sh &
-PID=-1
+PID=$$
 
 # wait forever
-while true
+signals_wait_forever
-do
-  tail -f /dev/null & wait ${!}
-done
 
 # https://docs.docker.com/compose/faq/
 # https://medium.com/@gchudnov/trapping-signals-in-docker-containers-7a57fdda7d86

app/signals.sh

@@ -1,5 +1,3 @@
-PID=0
-
 signals_trap_with_arg() {
     func="$1" ; shift
     for sig ; do
@@ -8,14 +6,20 @@ signals_trap_with_arg() {
     done
 }
 
-func_trap() {
+signals_wait_forever() {
-    echo "Trapped: $1"
+    while true
-    echo "Killing ${PID}"
+    do
-    if [ ${PID} -ne 0 ]; then
+        tail -f /dev/null & wait ${!}
-        kill -SIGTERM "${PID}"
+    done
-        wait "${PID}"
+}
-    fi
-    ps -ef --forest
 
-    exit 143
+signal_name_to_number() {
+    SIGNAME="$1"
+    trap -l | sed -nr "s/.*\b([0-9]+)\) $SIGNAME.*/\1/p"
+}
+
+signal_return_val() {
+    SIGNAME="$1"
+    SIGNUM=$(signal_name_to_number ${SIGNAME})
+    echo "128 + $SIGNUM" | bc
 }