I am big fun of Docker, it makes development fast and reliable. Since I am a big fan, I am trying to use docker whenever I get the chance.

I have a many automated jobs running on daily basis. I have used to setup these cron jobs by running ansible scripts against my EC2 instance(s).

Lately I have tried to switch these cron jobs to a docker container and run them on ECS service.

ECS is an AWS service that let you run your docker containers on EC2 instance. Also they provide another service called ECR, which allows you to store your docker images, it is very similar to docker hub.

The setup is fairly easy I will share with you my Docker file, All you have to do, is to change the cron jobs upload your docker image and run it.



# Pull ubuntu image
FROM ubuntu:16.04
MAINTAINER ISSAM BEN <bensirhir.issam@gmail.com>

# Update aptitude
RUN apt-get update

# INSTALL syslog for debugging my cron jobs
RUN apt-get install -y rsyslog

# Optional: depending on your environment 
RUN apt-get install -y default-jdk

# Install cron
RUN apt-get install cron

# Build project
WORKDIR /root/

# Copy cron job file to cron directory
COPY my-cron-file /etc/cron.d/my-cron-file

# Give execution rights on the cron job
RUN chmod 0755 /etc/cron.d/my-cron-file

# Run the command on container startup and keep the container running as service
CMD /usr/sbin/cron -f | service rsyslog restart

Note : Make sure your cron job exists and has all the jobs you want to run

touch my-cron-file
echo " # This file contains cron jobs that runs every day at 08 o'clock.
00 08 * * 1-7  root your-command" > my-cron-file

Build & Push

Now let’s build the docker image.

docker build -t my-cron-container .

Now the image has been built we have to push it to ECR. Assuming you are familiar with AWS. Otherwise you can run the docker image anywhere and you are ready to go.

First Make sure you have AWS cli installed and have your AWS profile setup (check ~/.aws/).

  1. Login to ECR service (depending on your region)
eval $(aws ecr get-login --no-include-email --region us-east-1)
  1. Create your repository
aws ecr create-repository --repository-name project-x/my-cron
  1. Tag your image so you can push the image to this repository
docker tag my-cron-container:latest aws_account_id.dkr.ecr.region.amazonaws.com/project-a/my-cron:latest
docker push aws_account_id.dkr.ecr.region.amazonaws.com/project-x/my-cron:latest

Now your image on ECR, you can easily run it using ECS tasks. I will explain this part in another post.