Using the /etc/crontabs/root file

Dockerfile

@@ -1,7 +1,7 @@
 # docker run -d -p 8000:8000 alseambusher/crontab-ui
 FROM alpine:3.5
 
-RUN   mkdir /crontab-ui
+RUN   mkdir /crontab-ui; touch /etc/crontabs/root; chmod +x /etc/crontabs/root
 
 WORKDIR /crontab-ui
 
@@ -23,7 +23,7 @@ ENV   HOST 0.0.0.0
 
 ENV   PORT 8000
 
-ENV   CRON_PATH /crontab-ui/crontabs/
+ENV   CRON_PATH /etc/crontabs
 ENV   CRON_IN_DOCKER true
 
 EXPOSE $PORT

crontab.js

@@ -115,8 +115,12 @@ exports.set_crontab = function(env_vars, callback){
 
 		fs.writeFile(exports.env_file, env_vars, function(err) {
 			if (err) callback(err);
-
-			fs.writeFile(path.join(cronPath, "crontab"), crontab_string, function(err) {
+			// In docker we're running as the root user, so we need to write the file as root and not crontab
+			var fileName = "crontab"
+			if(process.env.CRON_IN_DOCKER !== undefined) {
+				fileName = "root"
+			}
+			fs.writeFile(path.join(cronPath, fileName), crontab_string, function(err) {
 				if (err) return callback(err);
 				/// In docker we're running crond using busybox implementation of crond
 				/// It is launched as part of the container startup process, so no need to run it again

supervisord.conf

@@ -2,7 +2,7 @@
 nodaemon=true
 
 [program:crontab]
-command=crond -l 2 -f -c %(CRON_PATH)s
+command=crond -l 2 -f -c %(ENV_CRON_PATH)s
 stderr_logfile = /var/log/crontab-stderr.log
 stdout_logfile = /var/log/crontab-stdout.log