Gracefully handle cases where the selected USER_ID and/or GROUP_ID exist

entrypoint.sh

@@ -9,19 +9,24 @@ if [ "$1" = 'startram.sh' ]; then
     ###
     # Tomcat user
     ###
-    groupadd -r tomcat -g ${GROUP_ID} && \
-    useradd -u ${USER_ID} -g tomcat -d ${CATALINA_HOME} -s /sbin/nologin \
-        -c "Tomcat user" tomcat
+    # create group for GROUP_ID if one doesn't already exist
+    if ! getent group $GROUP_ID &> /dev/null; then
+      groupadd -r tomcat -g $GROUP_ID
+    fi
+    # create user for USER_ID if one doesn't already exist
+    if ! getent passwd $USER_ID &> /dev/null; then
+      useradd -u $USER_ID -g $GROUP_ID tomcat
+    fi
+    # alter USER_ID with nologin shell and CATALINA_HOME home directory
+    usermod -d "${CATALINA_HOME}" -s /sbin/nologin $(id -u -n $USER_ID)
 
     ###
     # Change CATALINA_HOME ownership to tomcat user and tomcat group
     # Restrict permissions on conf
     # Ensure RAMADDA data directory is owned by tomcat
     ###
-
-    chown -R tomcat:tomcat ${CATALINA_HOME} && \
-        chown -R tomcat:tomcat ${DATA_DIR} && \
-        chmod 400 ${CATALINA_HOME}/conf/*
+    chown -R $USER_ID:$GROUP_ID ${CATALINA_HOME} ${DATA_DIR} && find ${CATALINA_HOME}/conf \
+        -type d -exec chmod 755 {} \; -o -type f -exec chmod 400 {} \;
 
     sync
     exec gosu tomcat "$@"