CloudFormation Template Generator

Scala DSL to create AWS CloudFormation (CFN) templates. The library allows for easier creation of the AWS CloudFormation JSON by writing Scala code to describe the AWS resources. Lets say we have a handful of CFN templates we want to maintain, and all of those templates use the same AMI. Instead of copying that information into all the templates, lets create an AMI component instead, and then load it into the actual templates.

Why not just write JSON? Because, who in their right mind would want to write all AWS resources in JSON?

Documentation

See the intro blog post.

To use this library, you must add the following resolver

resolvers ++= Seq(Resolver.jcenterRepo)

and the dependency

libraryDependencies ++= Seq (
  "com.monsanto.arch" %% "cloud-formation-template-generator" % "3.1.1"
).map(_.force())

to your build.sbt.

See the Scaladoc for detailed documentation and examples.

See the Change Log for information on new, changed, and deprecated featured.

Note: we are no longer using the git-flow develop/master branch paradigm. Please just branch off master and submit your PRs against it.

Components

Create a Template instance of resources and check out VPCWriter to help write it to a file.

To use the fancier parts of the routing DSL, be sure to import TransportProtocol._.

Misc Features

NEW since the blog post, say you have a topology with subnets across multiple AZ's and you want to specify an autoscaling group that spans them, using our fancy Builders methods. Well this is cross-cutting, so its not strictly nested, so you can use an evil evil var, or now you can use our Template.lookupResource[R <: Resource[R]](name: String) method on previous template parts to extract resources by name. Note this will produce a generation-time error if you lookup something that does not exist or has the wrong type (unfortunately not a generation-time compiler error as most of our other features):

describe("Template Lookup") {
  it("Should lookup resources with the correct type") {

    val expected = `AWS::EC2::VPC`(
      name = "TestVPC",
      CidrBlock = CidrBlock(0,0,0,0,0),
      Tags = Seq.empty[AmazonTag]
    )
    val template = Template.fromResource(expected)
  
    assert(expected === template.lookupResource[`AWS::EC2::VPC`]("TestVPC"))
}

Currently supported AWS resource types

AWS::AutoScaling::AutoScalingGroup
AWS::AutoScaling::LaunchConfiguration
AWS::AutoScaling::ScalingPolicy
AWS::CloudFormation::WaitCondition
AWS::CloudFormation::WaitConditionHandle
AWS::CloudWatch::Alarm
AWS::DynamoDB::Table
AWS::EC2::CustomerGateway
AWS::EC2::EIP
AWS::EC2::EIPAssociation
AWS::EC2::Instance
AWS::EC2::InternetGateway
AWS::EC2::KeyPair::KeyName
AWS::EC2::NatGateway
AWS::EC2::NetworkAcl
AWS::EC2::NetworkAclEntry
AWS::EC2::Route
AWS::EC2::RouteTable
AWS::EC2::SecurityGroup
AWS::EC2::SecurityGroupEgress
AWS::EC2::SecurityGroupIngress
AWS::EC2::Subnet
AWS::EC2::SubnetRouteTableAssociation
AWS::EC2::VPC
AWS::EC2::VPCGatewayAttachment
AWS::EC2::VPCPeeringConnection
AWS::EC2::VPNConnection
AWS::EC2::VPNConnectionRoute
AWS::EC2::VPNGateway
AWS::EC2::Volume
AWS::EC2::VolumeAttachment
AWS::Elasticsearch::Domain
AWS::ElasticLoadBalancing::LoadBalancer
AWS::ElasticBeanstalk::Application
AWS::ElasticBeanstalk::ApplicationVersion
AWS::ElasticBeanstalk::ConfigurationTemplate
AWS::ElasticBeanstalk::Environment
AWS::IAM::AccessKey
AWS::IAM::Group
AWS::IAM::InstanceProfile
AWS::IAM::ManagedPolicy
AWS::IAM::Policy
AWS::IAM::Role
AWS::IAM::User
AWS::Lambda::EventSourceMapping
AWS::Lambda::Function
AWS::Lambda::Permission
AWS::RDS::DBInstance::Engine
AWS::RDS::DBInstance::StorageType
AWS::RDS::DBInstance
AWS::RDS::DBParameterGroup
AWS::RDS::DBSecurityGroup
AWS::RDS::DBSubnetGroup
AWS::Redshift::Cluster
AWS::Redshift::ClusterSecurityGroup
AWS::Redshift::ClusterSecurityGroupIngress
AWS::Redshift::ClusterParameterGroup (along with helper RedshiftClusterParameter type)
AWS::Redshift::ClusterSubnetGroup
AWS::Route53::HostedZone
AWS::Route53::RecordSet
AWS::S3::Bucket
AWS::S3::BucketPolicy
AWS::SNS::Topic
AWS::SNS::TopicPolicy
AWS::SQS::Queue
AWS::SQS::QueuePolicy

Custom types

This project packages certain useful custom CloudFormation types. These are Lambda backed types that perform tasks that CloudFormation does not natively support. In order to use them, you must upload the Lambda function to your account and region. The code for these functions is found in this repo under assets/custom-types.

Remote Route 53 entries

A given domain (or hosted zone, more specifically) must be managed out of a single AWS account. This poses problems if you want to create resources under that domain in templates that will run out of other accounts. A CloudFormation template can only work in one given account. However, with Cloud Formation's custom type functionality, we use custom code to assume a role in the account that owns the hosted zone. This requires some setup steps for each hosted zone and each account. For instructions, please see: https://github.com/MonsantoCo/cloudformation-template-generator/assets/custom-types/remote-route53/README.md for more.

Working with Cloudformation Concatenating

In the CloudFormation DSL, there is support for concatenating strings, parameters, and function calls together to build strings. This can get really ugly as they are chained together. There is a string interpolator to make this easier.

Releasing

This project uses the sbt release plugin. After the changes you want to release are committed on the master branch, you simple need to run two commands to publish the library and its documentation.

sbt release
sbt ghpages-push-site

aniketbhatnagar/cloudformation-template-generator