better crash resilience

entry.sh

@@ -1,4 +1,14 @@
-#!/bin/sh
+#!/bin/bash
+
+ilog() {
+	echo "[INF] " $@ 1>&2
+}
+wlog() {
+	echo "[WRN] " $@ 1>&2
+}
+elog() {
+	echo "[ERR] " $@ 1>&2
+}
 
 # signal handler for graceful shutdown of the container
 nice_exit() {
@@ -14,10 +24,10 @@ trap nice_exit INT TERM
 # we require an environment variable MAIL_DOMAIN to be present
 if [ -z "$MAIL_DOMAIN" ]; then
 	if [ ! -z "$PF_MYDOMAIN" ]; then
-		echo "INFO: MAIL_DOMAIN is not set, using PF_MYDOMAIN ('$PF_MYDOMAIN')"
+		ilog "MAIL_DOMAIN is not set, using PF_MYDOMAIN ('$PF_MYDOMAIN')"
 		export MAIL_DOMAIN="$PF_MYDOMAIN"
 	else
-		echo "WARN: please set the MAIL_DOMAIN environment variable to your FQDN. using 'localhost'"
+		wlog "please set the MAIL_DOMAIN environment variable to your FQDN. using 'localhost'"
 		export MAIL_DOMAIN=localhost
 	fi
 fi
@@ -30,15 +40,15 @@ echo "$MAIL_DOMAIN" > /etc/postfix/vhosts
 /usr/local/bin/add_mailbox.sh postmaster
 echo "changeme" | /usr/local/bin/add_user.sh postmaster
 
-echo "INFO: configuring courier imap"
+ilog "configuring courier imap"
 for VAR in $(env | grep '^CO_' | tr '[:upper:]' '[:lower:]'); do
 	CONFVAR=$(echo "$VAR" | cut -d= -f1 | cut -c 4-)
 	CONFVAL=$(echo "$VAR" | cut -d= -f2)
 	echo "configuring $CONFVAR = $CONFVAL"
 	sed -i "s/^$CONFVAR=.*$/$CONFVAR=$CONFVAL/" /etc/courier/imapd-ssl
 done
 
-echo "INFO: configuring postfix smtp"
+ilog "configuring postfix smtp"
 for VAR in $(env | grep '^PF_' | tr '[:upper:]' '[:lower:]'); do
 	CONFVAR=$(echo "$VAR" | cut -d= -f1 | cut -c 4- | tr '[:upper:]' '[:lower:]')
 	CONFVAL=$(echo "$VAR" | cut -d= -f2)
@@ -56,7 +66,7 @@ KEYFILE="$(postconf smtp_tls_key_file | cut -d ' ' -f3)"
 DHFILE='/etc/postfix/dh512.pem'
 IMAPCERTFILE='/etc/courier/imapd.pem' # default from /etc/courier/imapd-ssl
 if [ ! -z "$CERTFILE" ]; then
-	echo "INFO: building courier certificate file based on $CERTFILE, $KEYFILE and $DHFILE"
+	ilog "building courier certificate file based on $CERTFILE, $KEYFILE and $DHFILE"
 	cat "$CERTFILE" "$KEYFILE" "$DHFILE" > $IMAPCERTFILE
 fi
 
@@ -71,20 +81,44 @@ sleep 1
 /etc/init.d/courier-imap start
 /etc/init.d/courier-imap-ssl start
 
-SASL_PID=$(cat /var/spool/postfix/var/run/saslauthd/saslauthd.pid)
-#while [ ! -e "/var/spool/postfix/pid/master.pid" ]; do sleep 1; done
-#POSTFIX_PID=$(cat /var/spool/postfix/pid/master.pid | tr -d ' ')
+wait_and_get_socket() {
+	sock_file="$1"
+	timeout="$2"
 
-#tail -f /var/log/syslog
-#while [ ! -e "/var/log/mail.log" ]; do sleep 1; done
-#tail -f /var/log/auth.log /var/log/mail.log /var/log/mail.err &
+	if [ -z "$timeout" ]; then timeout=5; fi
 
-echo "INFO: running and waiting for pid $SASL_PID to exit..."
-# we cannot simply `wait` here, as it is not our child process...
-#wait "$SASL_PID"
-tail --pid=$SASL_PID -f /var/log/syslog &
-#tail --pid=$SASL_PID -f /dev/null &
-wait $!
+	i=0
+	while [ ! -e "${sock_file}" -a "$i" -lt "$timeout" ]; do
+		i="$(expr "$i" '+' 1)"
+		sleep 1
+	done
 
-echo "INFO: pid $SASL_PID exited. Bye-bye!"
+	if [ "$i" -eq "$timeout" ]; then
+		elog "waiting for socket file ${sock_file} timed out."
+		exit 1
+	fi
 
+	cat "${sock_file}"
+}
+
+SASL_PID=$(wait_and_get_socket /var/spool/postfix/var/run/saslauthd/saslauthd.pid)
+IMAPD_PID=$(wait_and_get_socket /var/run/courier/imapd.pid)
+IMAPD_SSL_PID=$(wait_and_get_socket /var/run/courier/imapd-ssl.pid)
+POSTFIX_PID=$(wait_and_get_socket /var/spool/postfix/pid/master.pid | tr -d ' ')
+
+ilog "running and waiting for pids saslauthd: $SASL_PID, imapd: $IMAPD_PID, imapd_ssl: $IMAPD_SSL_PID, postfix: $POSTFIX_PID to exit..."
+
+# we cannot simply `wait` here, as it is not our child process...
+tail --pid=$SASL_PID -f /var/log/auth.log &
+SASL_TAIL_PID="$!"
+# no idea what /var/log/btmp is, but there is no explicit logfile for imapd and imapd_ssl
+tail --pid=$IMAPD_PID -f /var/log/btmp &
+IMAPD_TAIL_PID="$!"
+tail --pid=$IMAPD_SSL_PID -f /var/log/syslog &
+IMAPD_SSL_TAIL_PID="$!"
+tail --pid=$POSTFIX_PID -f /var/log/mail.log &
+POSTFIX_TAIL_PID="$!"
+
+wait -n -p EXITED_PID "$SASL_TAIL_PID" "$IMAPD_TAIL_PID" "$IMAPD_SSL_TAIL_PID" "$POSTFIX_TAIL_PID"
+
+ilog "pid $EXITED_PID exited. Bye-bye!"