Sceptre

About

Sceptre is a tool to drive AWS CloudFormation. It automates the mundane, repetitive and error-prone tasks, enabling you to concentrate on building better infrastructure.

Features

• Code reuse by separating a Stack's template and its configuration
• Support for templates written in JSON, YAML, Jinja2 or Python DSLs such as Troposphere
• Dependency resolution by passing of Stack outputs to parameters of dependent Stacks
• Stack Group support by bundling related Stacks into logical groups (e.g. dev and prod)
• Stack Group-level commands, such as creating multiple Stacks with a single command
• Fast, highly parallelised builds
• Built in support for working with Stacks in multiple AWS accounts and regions
• Infrastructure visibility with meta-operations such as Stack querying protection
• Support for inserting dynamic values in templates via customisable Resolvers
• Support for running arbitrary code as Hooks before/after Stack builds

Benefits

• Utilises cloud-native Infrastructure as Code engines (CloudFormation)
• You do not need to manage state
• Simple templates using popular templating syntax - Yaml & Jinja
• Powerful flexibility using a mature programming language - Python
• Easy to integrate as part of a CI/CD pipeline by using Hooks
• Simple CLI and API
• Unopinionated - Sceptre does not force a specific project structure

Install

Using pip

$ pip install sceptre

More information on installing sceptre can be found in our Installation Guide

Using Docker Image

View our Docker repository. Images available from version 2.0.0 onward.

To use our Docker image follow these instructions:

1. Pull the image docker pull cloudreach/sceptre:[SCEPTRE_VERSION_NUMBER] e.g. docker pull cloudreach/sceptre:2.5.0. Leave out the version number if you wish to run latest or run docker pull cloudreach/sceptre:latest.

2. Run the image. You will need to mount the working directory where your project resides to a directory called project. You will also need to mount a volume with your AWS config to your docker container. E.g.

docker run -v $(pwd):/project -v /Users/me/.aws/:/root/.aws/:ro cloudreach/sceptre:latest --help

If you want to use a custom ENTRYPOINT simply amend the Docker command:

docker run -ti --entrypoint='' cloudreach/sceptre:latest sh

The above command will enter you into the shell of the Docker container where you can execute sceptre commands - useful for development.

If you have any other environment variables in your non-docker shell you will need to pass these in on the Docker CLI using the -e flag. See Docker documentation on how to achieve this.

Example

Sceptre organises Stacks into "Stack Groups". Each Stack is represented by a YAML configuration file stored in a directory which represents the Stack Group. Here, we have two Stacks, vpc and subnets, in a Stack Group named dev:

$ tree
.
├── config
│   └── dev
│        ├── config.yaml
│        ├── subnets.yaml
│        └── vpc.yaml
└── templates
    ├── subnets.py
    └── vpc.py

We can create a Stack with the create command. This vpc Stack contains a VPC.

$ sceptre create dev/vpc.yaml

dev/vpc - Creating stack dev/vpc
VirtualPrivateCloud AWS::EC2::VPC CREATE_IN_PROGRESS
dev/vpc VirtualPrivateCloud AWS::EC2::VPC CREATE_COMPLETE
dev/vpc sceptre-demo-dev-vpc AWS::CloudFormation::Stack CREATE_COMPLETE

The subnets Stack contains a subnet which must be created in the VPC. To do this, we need to pass the VPC ID, which is exposed as a Stack output of the vpc Stack, to a parameter of the subnets Stack. Sceptre automatically resolves this dependency for us.

$ sceptre create dev/subnets.yaml
dev/subnets - Creating stack
dev/subnets Subnet AWS::EC2::Subnet CREATE_IN_PROGRESS
dev/subnets Subnet AWS::EC2::Subnet CREATE_COMPLETE
dev/subnets sceptre-demo-dev-subnets AWS::CloudFormation::Stack CREATE_COMPLETE

Sceptre implements meta-operations, which allow us to find out information about our Stacks:

$ sceptre list resources dev/subnets.yaml

- LogicalResourceId: Subnet
  PhysicalResourceId: subnet-445e6e32
  dev/vpc:
- LogicalResourceId: VirtualPrivateCloud
  PhysicalResourceId: vpc-c4715da0

Sceptre provides Stack Group level commands. This one deletes the whole dev Stack Group. The subnet exists within the vpc, so it must be deleted first. Sceptre handles this automatically:

$ sceptre delete dev

Deleting stack
dev/subnets Subnet AWS::EC2::Subnet DELETE_IN_PROGRESS
dev/subnets - Stack deleted
dev/vpc Deleting stack
dev/vpc VirtualPrivateCloud AWS::EC2::VPC DELETE_IN_PROGRESS
dev/vpc - Stack deleted

Note: Deleting Stacks will only delete a given Stack, or the Stacks that are directly in a given StackGroup. By default Stack dependencies that are external to the StackGroup are not deleted.

Sceptre can also handle cross Stack Group dependencies, take the following example project:

$ tree
.
├── config
│   ├── dev
│   │   ├── network
│   │   │   └── vpc.yaml
│   │   ├── users
│   │   │   └── iam.yaml
│   │   ├── compute
│   │   │   └── ec2.yaml
│   │   └── config.yaml
│   └── staging
│       └── eu
│           ├── config.yaml
│           └── stack.yaml
├── hooks
│   └── stack.py
├── templates
│   ├── network.json
│   ├── iam.json
│   ├── ec2.json
│   └── stack.json
└── vars
    ├── dev.yaml
    └── staging.yaml

In this project staging/eu/stack.yaml has a dependency on the output of dev/users/iam.yaml. If you wanted to create the Stack staging/eu/stack.yaml, Sceptre will resolve all of it's dependencies, including dev/users/iam.yaml, before attempting to create the Stack.

Usage

Sceptre can be used from the CLI, or imported as a Python package.

CLI

Usage: sceptre [OPTIONS] COMMAND [ARGS]...

  Sceptre is a tool to manage your cloud native infrastructure deployments.

Options:
  --version                  Show the version and exit.
  --debug                    Turn on debug logging.
  --dir TEXT                 Specify sceptre directory.
  --output [text|yaml|json]  The formatting style for command output.
  --no-colour                Turn off output colouring.
  --var TEXT                 A variable to replace the value of an item in
                             config file.
  --var-file FILENAME        A YAML file of variables to replace the values
                             of items in config files.
  --ignore-dependencies      Ignore dependencies when executing command.
  --merge-vars               Merge variables from successive --vars and var
                             files.
  --help                     Show this message and exit.

Commands:
  create         Creates a stack or a change set.
  delete         Deletes a stack or a change set.
  describe       Commands for describing attributes of stacks.
  estimate-cost  Estimates the cost of the template.
  execute        Executes a Change Set.
  generate       Prints the template.
  launch         Launch a Stack or StackGroup.
  list           Commands for listing attributes of stacks.
  new            Commands for initialising Sceptre projects.
  set-policy     Sets Stack policy.
  status         Print status of stack or stack_group.
  update         Update a stack.
  validate       Validates the template.

Python

Using Sceptre as a Python module is very straightforward. You need to create a SceptreContext, which tells Sceptre where your project path is and which path you want to execute on, we call this the "command path".

After you have created a SceptreContext you need to pass this into a SceptrePlan. On instantiation the SceptrePlan will handle all the required steps to make sure the action you wish to take on the command path are resolved.

After you have instantiated a SceptrePlan you can access all the actions you can take on a Stack, such as validate(), launch(), list() and delete().

from sceptre.context import SceptreContext
from sceptre.plan.plan import SceptrePlan

context = SceptreContext("/path/to/project", "command_path")
plan = SceptrePlan(context)
plan.launch()

Full API reference documentation can be found in the Documentation

Tutorial and Documentation

• Get Started
• Documentation

Communication

The Sceptre community uses a Slack channel #sceptre on the og-aws Slack for discussion. To join use this link http://slackhatesthe.cloud/ to create an account and join the #sceptre channel.

Contributing

See our Contributing Guide