AWS EC2 GET SSH CONFIG

Description

A simple dockerized python script that queries the AWS EC2 API with boto and generates a SSH config file to use. There are already similar scripts but I couldnt find a dockerized one that allows execution with one-line command. In order to generate names that you can easily use to ssh in the host option of the config file, this script reads the TAGS of each instance and tries to find a tag NAME on the instance and use its value. If this tag doesnt exist the public dns name is used to populate the host option.

Usage

Before using this script make sure:

• you have an ssh key file that will be used to connect to EC2 instances in /Users/$USER/.ssh/
• you have installed awscli
• run awscli configure to configure connection details to aws. If you have multi-factor auth enabled you ll need first to run aws sts get-session-token --serial-number arn:aws:iam::0123456789:mfa/<username here> --token-code <token here>
• use the details from the ouput of the above command and export as env variables:

export AWS_ACCESS_KEY_ID=#############
export AWS_SECRET_ACCESS_KEY=###############

(if multi-factor auth enabled also):

export AWS_SESSION_TOKEN=###############

And you are ready to generate the ssh config file! Example command shown below. The docker run command should specify:

• the path where your .ssh directory is, mount it as volume: -v ~/.ssh/:/root/.ssh/
• set the env vars AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY, AWS_SESSION_TOKEN(if needed), SSH_KEY_PATH

docker run -v ~/.ssh/:/root/.ssh/ -e "AWS_ACCESS_KEY_ID=$AWS_ACCESS_KEY_ID" -e "AWS_SECRET_ACCESS_KEY=$AWS_SECRET_ACCESS_KEY" -e "AWS_SESSION_TOKEN=$AWS_SESSION_TOKEN" -e "SSH_KEY_PATH=~/.ssh/ssh_example_name.pem" moustakis/aws-ec2-get-ssh-config:1.0

• by default is set AWS_DEFAULT_REGION=us-east-2 and INSTANCE_USERNAME=ubuntu you can also override these using the -e option:

docker run -v ~/.ssh/:/root/.ssh/ -e "AWS_ACCESS_KEY_ID=$AWS_ACCESS_KEY_ID" -e "AWS_SECRET_ACCESS_KEY=$AWS_SECRET_ACCESS_KEY" -e "AWS_SESSION_TOKEN=$AWS_SESSION_TOKEN" -e "SSH_KEY_PATH=~/.ssh/ssh_example_name.pem" -e "AWS_DEFAULT_REGION=us-east-1" moustakis/aws-ec2-get-ssh-config:1.0

On successful execution you should see a message: File updated: /root/.ssh/aws_ec2.config The /root location refers to the path inside the container. Locally you should have have generated the file under /Users/$USER/.ssh/. Go to this directory and rename the file to config and you are good to go!

Now you can use it to ssh to AWS EC2 instances by using the name after every host value. For example for an entry:

##########################
host dummy_name
    Hostname #.#.#.#
    IdentityFile ~/.ssh/ssh_example_name.pem
    user ubuntu
##########################

You can just use ssh dummy_name to connect to the instance, Happy SSHing!