Elastic Compute Cloud (EC2)

Amazon Elastic Compute Cloud (Amazon EC2)

Pro

LocalStack Pro supports the Docker backend for running instances.

The Docker backend uses the Docker Engine to emulate EC2 instances. All limitations that apply to containers apply to EC2 instances backed by the Docker manager, including root access and networking. Access to the Docker socket is required which can be made available to LocalStack by mounting the socket file during launch.

Instances have the Docker socket (/var/run/docker.sock) mounted inside them, making Docker-in-Docker use cases possible.

Base Images

LocalStack uses a naming scheme to recognise and manage the containers and images associated with it. Containers are named localstack-ec2.<InstanceId>, while images are tagged localstack-ec2/<AmiName>:<AmiId>.

The Docker backend treats Docker images with the above naming scheme as AMIs. For example, the following command can be used to associate the Ubuntu Focal image as ami-000001.

$ docker tag ubuntu:focal localstack-ec2/ubuntu-focal-ami:ami-000001

These Docker-backed AMIs have the resource tag ec2_vm_manager:docker and can be listed with the following command:

$ awslocal ec2 describe-images --filters Name=tag:ec2_vm_manager,Values=docker

All other AMIs are ‘mocked’ and are based off the community edition of LocalStack. Attempting to launch Dockerised instances with these AMIs will return InvalidAMIID.NotFound error.

Networking

LocalStack supports assignment of unique private IP addresses for Dockerised instances. To leverage this feature, it is necessary to run the LocalStack daemon process on the host which takes care of creating and managing networking on the host system.

$ pip install localstack[runtime]
$ export LOCALSTACK_API_KEY=...
$ localstack daemons start

The address for SSH access to the instance is printed in the logs when the instance is initialised.

2022-03-21T14:46:49.540:INFO:localstack_ext.services.ec2.vmmanager.docker: Instance i-f6a80f48 will be accessible via SSH at: 192.168.123.25:22, 127.0.0.1:48805

If the LocalStack daemon is not running, the instance will be only accessible over SSH at 127.0.0.1 and the specified port.

The LocalStack daemon is supported on Linux and MacOS.

Security Groups are not applied to Dockerised instances. Ports other than 22 (SSH) are currently not exposed.

Operations

The Docker backend supports following operations:

OperationNotes
CreateImageUses Docker commit to take a snapshot of a running instance into a new AMI
DescribeImagesRetrieve a list of Docker images available for use within LocalStack
DescribeInstancesDescribe ‘mock’ instances as well as Docker-backed instances. Docker-backed instances have the resource tag ec2_vm_manager:docker
RunInstancesLaunch an instance. Supports ImageId, MaxCount, KeyPair and UserData parameters
StopInstancesCorresponds to pausing a container
StartInstancesCorresponds to unpausing a container
TerminateInstancesCorresponds to stopping a container