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Deploying a Containerised Flask App to AWS EC2

AWSEC2DockerECRDevOps July 2026

Deploying a Containerised Flask App to AWS EC2

Overview

This guide covers pushing a Docker image to AWS ECR and running it on an EC2 instance.

Prerequisites

  • Docker installed and running locally
  • AWS CLI installed (aws --version)
  • An AWS account with ECR and EC2 access

Step 1: Configure the AWS CLI

aws configure

Enter your:

  • AWS Access Key ID
  • AWS Secret Access Key
  • Default region: eu-west-2
  • Default output format: json

Verify you are logged in:

aws sts get-caller-identity

Step 2: Create an ECR Repository

aws ecr create-repository --repository-name contain-my-flask --region eu-west-2

Note the repositoryUri in the response — you will need it for tagging and pushing.

Step 3: Build the Docker Image for Linux/amd64

If you are on Apple Silicon (M1/M2), you must build for the correct platform:

docker buildx build --platform linux/amd64 -t contain-my-flask:1.0.0 .

Step 4: Authenticate Docker to ECR

aws ecr get-login-password --region eu-west-2 | docker login --username AWS --password-stdin 664047078509.dkr.ecr.eu-west-2.amazonaws.com

Step 5: Tag and Push the Image to ECR

Tag the image with the ECR URI:

docker tag contain-my-flask:1.0.0 664047078509.dkr.ecr.eu-west-2.amazonaws.com/contain-my-flask:1.0.0

Push the image:

docker push 664047078509.dkr.ecr.eu-west-2.amazonaws.com/contain-my-flask:1.0.0

Step 6: Launch an EC2 Instance

In the AWS Console:

  1. Go to EC2 → Launch instance
  2. Name: Flask Server
  3. AMI: Amazon Linux 2023 (free tier)
  4. Instance type: t2.micro (free tier)
  5. Create or select a key pair — download the .pem file
  6. Security group inbound rules:
    • SSH (port 22) — My IP
    • HTTP (port 80) — Anywhere (0.0.0.0/0)
  7. Click Launch instance

Step 7: Attach an IAM Role to the EC2 Instance

So the instance can pull from ECR without manual credentials:

  1. Go to IAM → Roles → Create role
  2. Select AWS service → EC2 → Next
  3. Attach policy: AmazonEC2ContainerRegistryReadOnly
  4. Name the role ec2-ecr-role → Create role
  5. Go to EC2 → select your instance → Actions → Security → Modify IAM role
  6. Select ec2-ecr-role → Update IAM role

Step 8: SSH into the EC2 Instance

Fix the key file permissions first:

chmod 400 ~/Desktop/your-key.pem

Connect to the instance:

ssh -i ~/Desktop/your-key.pem ec2-user@<public-ip>

Step 9: Install and Start Docker on the Instance

sudo yum install -y docker
sudo service docker start

Step 10: Authenticate Docker to ECR (on the Instance)

aws ecr get-login-password --region eu-west-2 | sudo docker login --username AWS --password-stdin 664047078509.dkr.ecr.eu-west-2.amazonaws.com

Step 11: Pull the Image from ECR

sudo docker pull 664047078509.dkr.ecr.eu-west-2.amazonaws.com/contain-my-flask:1.0.0

Step 12: Run the Container

sudo docker run -d -p 80:3030 664047078509.dkr.ecr.eu-west-2.amazonaws.com/contain-my-flask:1.0.0
  • -d runs the container in the background
  • -p 80:3030 maps port 80 on the EC2 instance to port 3030 inside the container

Verify the container is running:

sudo docker ps

Step 13: Access the App

Open your browser and visit:

http://<your-ec2-public-ip>

Use http:// not https://.

Troubleshooting

SSH times out — your IP may have changed. Update the SSH inbound rule in the security group to My IP.

No matching manifest for linux/amd64 — you built the image on Apple Silicon. Rebuild with --platform linux/amd64 and push again.

Unable to locate credentials on EC2 — the IAM role is not attached. Follow Step 7.