I wrote a suite of Ansible playbooks to provision an ECS (Elastic Container Service) cluster on AWS, running a webapp deployed on Docker containers in the cluster and load balanced from an ALB (Application Load Balancer), with the Docker image for the app pulled from an ECR (Elastic Container Registry) repository.
This is a follow-up to my project/article “How to use Ansible to provision an EC2 instance with an app running in a Docker container” which explains how to get a containerised Docker app running on an regular EC2 instance, using Docker Hub as the image repo. That could work well as a simple Staging environment, but for Production it’s desirable to easily cluster and scale the containers with a load balancer, so I came up with this solution for provisioning/deploying on ECS which is well-suited for this kind of flexibility. (To quote AWS: “Amazon ECS is a fully managed container orchestration service that makes it easy for you to deploy, manage, and scale containerized applications”.) This solution also uses Amazon’s own ECR for Docker images, rather than Docker Hub.
Continue reading “How to provision an ECS cluster and deploy a webapp on it with load-balanced Docker containers, using Ansible”
I’ve recently produced a series of articles aimed at startups, entrepreneurial solo developers, etc. wanting to take their first steps into Amazon Web Services (AWS) setups for app deployment:
I then wanted to move on from discussing manual setup via the GUI interface of the AWS web console, to DevOps-style command-line programmatic setup for automated provisioning of an AWS infrastructure for app deployment, i.e. infrastructure as code (IaC). I have therefore created a suite of Ansible playbooks to provision an entire AWS infrastructure with a Staging instance and an auto-scaled load-balanced Production environment, and to deploy a webapp thereon. The resulting set of Ansible AWS provisioning playbooks and associated files can be found in a repository on my GitHub, so go ahead and grab it from there if you want to try them out. Keep reading for information on how to set up and use the playbooks (and you can also refer to the README in the repo folder, which contains much of the same information).
With these playbooks, firstly the EC2 SSH key and Security Groups are created, then a Staging instance is provisioned, then the webapp is deployed on Staging from GitHub, then an image is taken from which to provision the Production environment. The Production environment is set up with auto-scaled EC2 instances running behind a load balancer. Finally, DNS entries are added for the Production and Staging environments.
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When you want to run your web application on more than one EC2 instance for scaling and redundancy purposes, you will probably require some form of load balancer to distribute incoming requests evenly across the instances. There are various possible solutions for this.
One option is to launch another EC2 instance and install a load balancer on it yourself. There are quite a few open source load balancing options, though I would tend to recommend HAProxy as it’s fast, efficient, secure, and very flexible. This option involves setting up your Linux instance and installing the software you need yourself, then configuring your chosen load balancer and installing your SSL certificates, etc. Additionally you would need to estimate the necessary instance size to run the load balancing software without getting overloaded and slowing the site down (bearing in mind that SSL termination can be particularly CPU-intensive), then monitoring it accordingly.
Unless there’s a particular reason to take the approach of installing a load balancer on an EC2 instance, a simpler and more effective option – especially for companies taking their first steps into scaling multiple instances for their application – is likely to be Amazon’s own ELB (Elastic Load Balancer). This doesn’t require an EC2 instance with Linux setup, software installation and configuration, etc. It provides a simple interface with easy SSL termination and it will scale itself automatically as needed, so there is little required in the way of planning and monitoring.
Continue reading “How to choose and set up a load balancer in AWS”