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Deploy Docker Container on AWS Quickly Using Cloud Init

One can use "cloud-config" scripts (executed by "cloud-init") to quickly spin up a minimal Ubuntu instance that will then:

Install the necessary packages for docker.
Pull the relevant docker image
Deploy the image however you like (docker run ....)

This makes it very quick to deploy your code, and is a good step on the way to using code to manage your infrastructure.

The cloud-config script below can be used on anything, not just AWS. E.g. use it on your KVM guests.

Steps

First select the Ubuntu 20.04 image from the defaults.

Copy the cloud-config script below...

#cloud-config

packages:
  - docker.io

# create the docker group
groups:
  - docker

# Add default auto created user to docker group
system_info:
  default_user:
    groups: [docker]

runcmd:
 - /usr/bin/sleep 10
 - /usr/bin/docker pull tutum/hello-world
 - /usr/bin/docker run -d -p 80:80 --restart=always -e SOME_VAR="SOME VALUE" tutum/hello-world
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... and paste it into the user_data field as shown below before deploying:

Then just wait a while :)

If it appears to not work, be sure to log into the EC2 instance and check the logs at /var/log/cloud-init-output.log

Using Docker PPA

If you want to install Docker from the PPA instead, then change the cloud-init config to:

#cloud-config

apt:
  sources:
    docker.list:
      source: deb [arch=amd64] https://download.docker.com/linux/ubuntu $RELEASE stable
      keyid: 9DC858229FC7DD38854AE2D88D81803C0EBFCD88

packages:
  - docker-ce
  - docker-ce-cli

# create the docker group
groups:
  - docker

# Add default auto created user to docker group
system_info:
  default_user:
    groups: [docker]

runcmd:
  - /usr/bin/sleep 10
  - /usr/bin/docker pull tutum/hello-world
  - /usr/bin/docker run -d -p 80:80 --restart=always -e SOME_VAR="SOME VALUE" tutum/hello-world
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Using A Private Registry

If you are using a private registry to host your docker images, then you need to add some commands to perform a docker login like so:

#cloud-config

packages:
  - docker.io

# create the docker group
groups:
  - docker

users:
  - name: ubuntu
    groups: docker
    home: /home/ubuntu
    shell: /bin/bash
    sudo: ALL=(ALL) NOPASSWD:ALL

# Add default auto created user to docker group
system_info:
  default_user:
    groups: [docker]

runcmd:
  - docker login --username REGISTRY_USERNAME_HERE --password-stdin REGISTRY_PASSWORD_HERE
  - docker pull registry.mydomain.com/myImageName
  - docker run  -e "MY_VAR=myValue" registry.mydomain.com/myImageName
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Using AWS ECR

If you are using AWS's Elastic Container Registry, then you will need to login using IAM credentials like so (because the code to get the password, gets a password that expires)

#cloud-config

packages:
  - docker.io

# create the docker group
groups:
  - docker

users:
  - name: ubuntu
    groups: docker
    home: /home/ubuntu
    shell: /bin/bash
    sudo: ALL=(ALL) NOPASSWD:ALL

# Add default auto created user to docker group
system_info:
  default_user:
    groups: [docker]

runcmd:
  - apt update && apt install python3-pip -y && pip3 install awscli
  - export AWS_ACCESS_KEY_ID=IAM_ECR_KEY_HERE
  - export AWS_SECRET_ACCESS_KEY=IAM_ECR_SECRET_HERE
  - aws ecr get-login-password --region eu-west-2 | docker login --username AWS --password-stdin 000000000000.dkr.ecr.eu-west-2.amazonaws.com
  - docker pull 000000000000.dkr.ecr.eu-west-2.amazonaws.com/myImageName
  - docker run  -e "MY_VAR=myValue" 000000000000.dkr.ecr.eu-west-2.amazonaws.com/myImageName
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References

Stack Overflow - How do I install docker using cloud-init?

Last updated: 17th June 2021
First published: 24th September 2020

This blog is created by Stuart Page

I'm a freelance web developer and technology consultant based in Surrey, UK, with over 10 years experience in web development, DevOps, Linux Administration, and IT solutions.

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