KnuckleCluster

Have you ever wanted to shuck away the hard, rough exterior of an ECS cluster and get to the soft, chewy innards? Sounds like you need KnuckleCluster! This tool provides scripts, invoked via cli or rakefile, to list, connect to and/or run commands on ecs agents and containers via ssh. This makes it very easy to interrogate ECS agents and containers without having to go digging for IP addresses and things. Primarily created as a tool to connect to instances in an ECS cluster and see what is running on them, it has evolved slightly to include the ability to list instances in spot requests and auto-scaling groups.

Features

• See what agents in your ECS cluster are doing
• Easily connect to running agents
• Easily connect and get a console inside running containers
• Create shortcuts to oft-used commands and run them easily
• Optionally integrates with aws-vault for AWS authentication

Development Status

Is being used in production for various projects and is considered stable. Any new features/bug fixes etc are most welcome!

Installation

KnuckleCluster can be used in two ways:

1. As a system-wide executable with a config file (preferred)
2. As a rake task in your project

Install the executable with:

$ gem install knuckle_cluster

OR

Add this line to your application's Gemfile:

source 'https://rubygems.envato.com/' do
  gem 'knuckle_cluster'
end

And then execute:

$ bundle

Usage

Knuckle Cluster can be used either as a part of an application via a rakefile, or at a system level.

You'll need to execute knuckle_cluster with appropriate AWS permissions on the cluster in question, stored in your ENV. I like to use aws-vault to handle this for me.

System usage

Create a file: ~/.ssh/knuckle_cluster. This is the config file that will be used to make connections from the command line. It is a yaml file. The connection name is the key, and all parameters are below it. EG:

platform:
  cluster_name: platform-ecs-cluster-ABC123
  region: us-east-1
  bastion: platform_bastion
  rsa_key_location: ~/.ssh/platform_rsa_key
  ssh_username: ubuntu
  sudo: true
  aws_vault_profile: platform_super_user
  shortcuts:
    console:
      container: web
      command: bundle exec rails console
    db:
      container: worker
      command: script/db_console
  tunnels:
    db:
      local_port: 54321
      remote_host: postgres-db.yourcompany.com
      remote_port: 5432
  hide:
    container: some_container_regex_i_dont_care_about
    task: some_task_regex_i_dont_care_about

You can also use inheritance to simplify the inclusion of multiple similar targets:

super_platform:
  <<: *default_platform
  cluster_name: super-platform-ecs-cluster-ABC123

ultra_platform:
  <<: *default_platform
  cluster_name: ultra-platform-ecs-cluster-DEF987
  sudo: false

default_platform: &default_platform
  region: us-east-1
  bastion: platform_bastion
  rsa_key_location: ~/.ssh/platform_rsa_key
  ssh_username: ubuntu
  sudo: true
  aws_vault_profile: platform_super_user

other_platform: &other_platform
  region: us-east-1
  bastion:
    username: ubuntu
    host: bastion.endpoint.example.com
    rsa_key_location: ~/.ssh/bastion_rsa_key
  rsa_key_location: ~/.ssh/platform_rsa_key
  ssh_username: ubuntu
  sudo: true
  aws_vault_profile: platform_super_user

See Options for Knuckle Cluster below for a list of what each option does.

Command line options:

knuckle_cluster list - list all available clusters
knuckle_cluster CLUSTER_PROFILE agents - list all agents and select one to start a shell
knuckle_cluster CLUSTER_PROFILE containers - list all containers and select one to start a shell
knuckle_cluster CLUSTER_PROFILE logs CONTAINER_NAME - tail the logs for a container
knuckle_cluster CLUSTER_PROFILE CONTAINER_NAME [OPTIONAL COMMANDS] - connect to a container and start a shell or run a command
knuckle_cluster CLUSTER_PROFILE SHORTCUT_NAME - run a shortcut defined in your knuckle_cluster configuration
knuckle_cluster CLUSTER_PROFILE tunnel TUNNEL_NAME - open a tunnel defined in your knuckle_cluster configuration
knuckle_cluster CLUSTER_PROFILE scp source destination - copied a file via scp to or from a container or agent. Use container:<location> or agent:<location>

Rakefile usage

It takes one argument at minimum: cluster_name . A region is likely also required as it will default to us-east-1. Eg:

kc = KnuckleCluster.new(
  cluster_name: 'platform-ecs-cluster-ABC123',
  region: 'us-east-1',
  bastion: 'platform_bastion',
  rsa_key_location: "~/.ssh/platform_rsa_key",
  ssh_username: "ubuntu",
  sudo: true
)
task :agents do
  kc.connect_to_agents
end

task :containers do
  kc.connect_to_containers
end

invoke with rake agents or rake containers

Once you have an instance of KnuckleCluster, you can now do things!

$ knuckle_cluster super_platform containers

Which will give you the output and run bash for you on the actual docker container:

Listing Containers
TASK              | AGENT               | INDEX | CONTAINER
------------------|---------------------|-------|--------------------
task-one          | i-123abc123abc123ab | 1     | t1-container-one
task-two          | i-123abc123abc123ab | 2     | t2-container-one
                  |                     | 3     | t2-container-two
task-three        | i-456def456def456de | 4     | t3-container-one
                  |                     | 5     | t3-container-two
                  |                     | 6     | t3-container-three

Connect to which container?

Same with connecting directly to agents

$ knuckle_cluster super_platform agents

Listing Agents
INDEX | INSTANCE_ID         | TASK       | CONTAINER
------|---------------------|------------|--------------------
1     | i-123abc123abc123ab | task-one   | t1-container-one
      |                     | task-two   | t2-container-one
      |                     |            | t2-container-two
2     | i-456def456def456de | task-three | t3-container-one
      |                     |            | t3-container-two
      |                     |            | t3-container-three

Connect to which agent?

Both connect_to_containers and connect_to_agents can have the following optional arguments:

Argument	Description
command	Runs a command on the specified container/agent. When connecting to containers, this defaults to bash
auto	Automatically connects to the first container/agent it can find. Handy when used in conjunction with command.

Eg: To connect to a container, echo something and then immediately disconnect you could use:

kc.connect_to_containers(auto: true, command: "echo I love KnuckleCluster!")

Options for Knuckle Cluster

Possible options are below. If left blank, they will be ignored and defaults used where available.:

Argument	Description
cluster_name	The name of the cluster (not the ARN). eg 'my-super-cluster'. One of cluster_name,spot_request_id or asg_name is required.
spot_request_id	The spot request ID you are connecting to. eg 'sfr-abcdef'. One of cluster_name,spot_request_id or asg_name is required.
asg_name	The auto-scaling group name you are connecting to. eg 'very-scaly-group'. One of cluster_name,spot_request_id or asg_name is required.
region	The AWS region you would like to use. Defaults to us-east-1
bastion	if you have a bastion to proxy to your ecs cluster via ssh, put the name of it here as defined in your ~/.ssh/config file. Alternatively, this can be a collection of keys for username, host, and rsa_key_location
rsa_key_location	The RSA key needed to connect to an ecs agent eg ~/.ssh/id_rsa.
ssh_username	The username to conncet. Will default to ec2-user
sudo	true or false - will sudo the docker command on the target machine. Usually not needed unless the user is not a part of the docker group.
aws_vault_profile	If you use the aws-vault tool to manage your AWS credentials, you can specify a profile here that will be automatically used to connect to this cluster.
profile	Another profile to inherit settings from. Settings from lower profiles can be overridden in higher ones.
hide	allows you to specify a regex for either task or container to omit these from being shown

FAQ

Ruby 3 related issue:

ERROR: There was a problem loading your configuration: Alias parsing was not enabled. To enable it, pass `aliases: true` to `Psych::load` or `Psych::safe_load`.

This is an issue with Psych changing the default behaviour around expanding aliases in Ruby 3. See this issue for a workaround.

Spot Fleets

If you wish to see what instances are running within a spot fleet, KnuckleCluster can do that too!. In your config, use spot_request_id instead of cluster_name. Note that the containers command will not work when invoking (use agents instead).

AutoScaling Groups

If you wish to see what instances are running within an ASG, KnuckleCluster can do that too!. In your config, use asg_name instead of cluster_name. Note that the containers command will not work when invoking (use agents instead).

SCP

You can use Knuckle Cluster to copy files in and out of agents or containers. Note that this will only work where one of the source or destination is your local machine, copying between containers is not yet supported. Use a syntax similar to existing scp syntax when specifying a source or destination, but use the keyword container or agent for the remote. When using one of these keywords, you will be prompted as to which agent/container you wish to use.

#Copy some_file.txt into a container at /app/some_file.txt
knuckle_cluster super_platform scp ./some_file.txt container:/app/some_file.txt

#Copy /app/some_file.txt from a remote container to ./some_file.txt on your local machine
knuckle_cluster super_platform scp container:/app/some_file.txt ./some_file.txt

#Copy some_file.txt into an agent at ~/some_file.txt
knuckle_cluster super_platform scp ./some_file.txt agent:~/some_file.txt

#Copy /app/some_file.txt from a remote container to ./some_file.txt on your local machine
knuckle_cluster super_platform scp agent:~/some_file.txt ./some_file.txt

Maintainer

Envato

Contributors

• Peter Hofmann
• Giancarlo Salamanca
• Jiexin Huang

License

KnuckleCluster uses MIT license. See LICENSE.txt for details.

Code of conduct

We welcome contribution from everyone. Read more about it in CODE_OF_CONDUCT.md

Contributing

For bug fixes, documentation changes, and small features:

1. Fork it ( https://github.com/[my-github-username]/knuckle_cluster/fork )
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create a new Pull Request

For larger new features: Do everything as above, but first also make contact with the project maintainers to be sure your change fits with the project direction and you won't be wasting effort going in the wrong direction.