Systems Manager (SSM)

Introduction

Systems Manager (SSM) is a management service provided by Amazon Web Services that helps you effectively manage and control your infrastructure resources. SSM simplifies tasks related to system and application management, patching, configuration, and automation, allowing you to maintain the health and compliance of your environment.

LocalStack allows you to use the SSM APIs in your local environment to run operational tasks on the Dockerized instances. The supported APIs are available on our API coverage page, which provides information on the extent of SSM’s integration with LocalStack.

Getting started

This guide is designed for users new to Systems Manager (SSM) and assumes basic knowledge of the AWS CLI and our awslocal wrapper script.

Start your LocalStack container using your preferred method with an additional EC2_VM_MANAGER=docker configuration variable. We will demonstrate how to use EC2 and SSM functionalities when using the Docker backend with LocalStack with the AWS CLI.

Create an EC2 instance

To get started, pull the ubuntu:focal image from Docker Hub and tag it as localstack-ec2/ubuntu-focal-docker-ami:ami-00a001. LocalStack uses a naming scheme to recognise and manage the containers and images associated with it. The container are named localstack-ec2.<InstanceId>, while images are tagged localstack-ec2/<AmiName>:<AmiId>.

$ docker pull ubuntu:focal
$ docker tag ubuntu:focal localstack-ec2/ubuntu-focal-docker-ami:ami-00a001

LocalStack’s Docker backend treats Docker images with the above naming scheme as AMIs. The AMI ID is the last part of the image tag, ami-00a001 in this case. You can run an EC2 instance using the RunInstances API. Execute the following command to create an EC2 instance using the ami-00a001 AMI.

$ awslocal ec2 run-instances \
    --image-id ami-00a001 --count 1

The following output would be retrieved:

{
    ...
    "Instances": [
        {
            ...
            "InstanceId": "i-abf6920789a06dd84",
            "InstanceType": "m1.small",
            ...
            "SecurityGroups": [],
            "SourceDestCheck": true,
            "Tags": [],
            "VirtualizationType": "paravirtual"
        }
    ],
    "OwnerId": "000000000000",
    "ReservationId": "r-e9b21a68"
    ...

You can copy the InstanceId value and use it in the following commands.

Send command using SSM

You can use the SendCommand API to send commands to the EC2 instance. The following command sends a cat lsb-release command in the /etc directory to the EC2 instance.

$ awslocal ssm send-command --document-name "AWS-RunShellScript" \
    --document-version "1" \
    --instance-ids i-abf6920789a06dd84 \
    --parameters "commands='cat lsb-release',workingDirectory=/etc"

The following output would be retrieved:

{
    "Command": {
        "CommandId": "23547a9b-6993-4967-9446-f96b9b5dac70",
        "DocumentName": "AWS-RunShellScript",
        "DocumentVersion": "1",
        "InstanceIds": [
            "i-abf6920789a06dd84"
        ],
        "Status": "InProgress"
    }
}

You can copy the CommandId value and use it in the following commands.

Retrieve the command output

You can use the GetCommandInvocation API to retrieve the command output. The following command retrieves the output of the command sent in the previous step.

$ awslocal ssm get-command-invocation \
    --command-id 23547a9b-6993-4967-9446-f96b9b5dac70 \
    --instance-id i-abf6920789a06dd84

Change the CommandId and InstanceId values to the ones you received in the previous step. The following output would be retrieved:

{
    "CommandId": "23547a9b-6993-4967-9446-f96b9b5dac70",
    "InstanceId": "i-abf6920789a06dd84",
    "DocumentName": "AWS-RunShellScript",
    "DocumentVersion": "1",
    "Status": "Success",
    "StandardOutputContent": "DISTRIB_ID=Ubuntu\nDISTRIB_RELEASE=20.04\nDISTRIB_CODENAME=focal\nDISTRIB_DESCRIPTION=\"Ubuntu 20.04.6 LTS\"\n",
    "StandardErrorContent": ""
}

Limitations

The following table highlights some differences between LocalStack SSM and AWS SSM.

The other limitations of LocalStack SSM are:

• Dockerized instances only support AWS-RunShellScript commands.
• Commands returning non-zero codes won’t capture standard output or error streams, leaving them empty.
• Shell constructs such as job controls (&&, ||), and redirection (>) are not supported.