Cloudformation Seed

Preface

This is a script that will help you deploy your Cloudformation project without hassle:

• Handle Cloudformation deployments of any scale
• Allow to do multiple deployments of the same code with a different installation name
• Automate Lambda code handling
• Get rid of hard dependencies of Cloudformation Exports, instead pass around Output values between stacks
• Package the whole deployment in a Docker image and version it

It will:

• Automatically create an S3 bucket according to the project name
• Upload the Cloudformation templates into the bucket
• Package and checksum your Lambda code and upload it into the bucket
• Upload arbitrary artifacts into the bucket so that they are available to your deployment
• Create and manage Cloudformation stacks
• Create, roll out and manage Stacksets

Requirements

You need a Mac, Linux or Windows machine/VM to run the Seed. On Windows it runs natively, as well as in WSL/WSL2.

Installation

Install it from PyPI:

$ pip install cloudformation-seed
$ cloudformation-seed --version

Or use a docker image from ghcr.io (use the version number instead of latest for stability):

$ docker pull ghcr.io/innablr/cloudformation-seed:latest
$ docker run ghcr.io/innablr/cloudformation-seed:latest cloudformation-seed --version

Quick start

First things first:

1. Create a new directory for your project
2. Copy everything from the examples directory to the root of the project
3. Edit parameters/dev.yaml to your needs
4. Add more templates with .cf.yaml extensions under the cloudformation directory and include them in parameters/dev.yaml

Finally:

Authenticate to AWS using your method of choice, make sure that you have set the AWS Region you need for deployment. Run cloudformation-seed -c my-project -i x0 -e dev -d my.domain.cld deploy

Optionally:

Take the dockerfiles and makefiles from the examples directory and massage them around to suit your needs.

Deep dive

Mandatory Cloudformation stack parameters

Every Cloudformation template you use has to have 4 mandatory parameters that will be supplied by the Seed:

1. TemplatesS3Bucket - the Seed will automatically create an S3 bucket and every template will have its name passed down in this parameter, so it can be made available to Lambda functions, autoscaling groups, e.t.c.
2. InstallationName - installation name is what makes you able to deploy your project multiple times without name clashes. Every template will have it in this parameter and you have to use it in the names of your resources to make them unique across multiple installations
3. RuntimeEnvironment - name of the runtime environment (read Deployment configuration)
4. Route53ZoneDomain - DNS domain associated with your deployment. The Seed doesn't require it to exist, you can use it as part of your resource naming convention

There are other builtin parameters that are populated automatically by the Seed if you declare them in your Cloudformation templates:

• ProductName - if you are using Seed's SSM parameter management, they are always references through /product_name/installation_name/parameter_name path. Product Name can be set through the -c parameter on the Seed command line. You can also have this value available to your Cloudformation templates through the ProductName builtin parameter
• AWSOrganizationID and AWSOrganizationARN - you can set the AWS Organization ID on the Seed command line. This will make the templates S3 bucket available to the entire AWS Organization, so you can use your lambdas in Cloudformation stacksets. You can also have these values available to your Cloudformation templates through the above parameters

Here's a snippet you can copy and paste:

Parameters:
  TemplatesS3Bucket:
    Type: String
    Description: S3 Bucket with the components templates
  InstallationName:
    Type: String
    Description: Unique DNS stack installation name
  RuntimeEnvironment:
    Type: String
    Description: The runtime environment config tag
    Default: dev
  Route53ZoneDomain:
    Type: String
    Description: Route53 zone domain that represents the environment

Seed bucket

The Seed will automatically create an S3 bucket for operating the deployment. The name of the bucket is derived from the installation name and project name from Makefile.particulars. The name of the bucket will be passed down to every Cloudformation template in your deployment as TemplatesS3Bucket

If you specify the ARN of your AWS Organization on the commandline the bucket will be shared with the entire Organization. This will allow you to use uploaded Lambda code in your stacksets (see lambda code handling below).

Deployment configuration

The -e dev parameter in the deployment directive above points to the configuration file dev.yaml located under the parameters directory.

You can have multiple runtime environments for the same project with different configuration, for example if you have dev, test and prod environments that reuse the same Cloudformation but need different configuration, for example VPC and subnet IDs.

A runtime environment is a YAML file that:

• defines the sequence in which the Cloudformation stacks will be deployed
• sets parameters for the Cloudformation stacks

You can also factor common configuration into separate YAML files and include them into one another using the !Include YAML tag:

  - name: centralservices-iam-set
    type: stackset                                       # set type to stackset
    template: sets/iam.cf.yaml
    parameters:                                          # parameters to the StackSet
      SSMLogsLambdaS3Key: !LambdaZip ssmLogsConfig.zip
      SAMLUsername: *SAML_USERNAME
      SAMLProviderName: *SAML_PROVIDER_NAME
    pilot:                                               # when StackSet is updated only update instances in these accounts
      accounts:
        - '000000000000'
    rollout: !Include rollout.yaml                       # manage StackSet instances

The runtime environment contains two sections:

common-parameters

In this section you can specify Cloudformation parameters that will be picked up by every stack in the deployment as a default value (i.e. if a stack has the same parameter on it it will take precedence)

Example:

common-parameters:
  VpcId: vpc-00000000

You can use !StackOutput (read below) in common-parameters and it will work as expected.

Instead of common-parameters you can also use YAML anchors like this:

SAMLUsername: &SAML_USERNAME okta_sso

stacks:
  - name: centralservices-iam-set
    type: stackset
    template: sets/iam.cf.yaml
    parameters:
      SSMLogsLambdaS3Key: !LambdaZip ssmLogsConfig.zip
      SAMLUsername: *SAML_USERNAME

You can also tag your stacks/stacksets by defining your tags as a dictionary and referencing them using the YAML anchors within your stacks like this:

tags_a: &TAGSA
  testkey1: testvalue1
  testkey2: testvalue2

tags_b: &TAGSB
  testkey3: testvalue3

  stacks:
    - name: example-stackset-template
      type: stackset
      template: sets/example-stackset-template.cf.yaml
      rollout:
        - account: '000000000000'
      tags: *TAGSA

    - name: my-project-kms-decrypt-lambda
      template: support/kms-parameters-lambda.cf.yaml
      parameters:
        LambdaSourceS3Key: !LambdaZip kmsParameters.zip
      tags: *TAGSB

stacks

Main configuration where you describe the Cloudformation stacks you want to deploy.

Example:

stacks:
  - name: in-cld-managed-zone                            # name of the CF stack, INSTALLATION_NAME will be prepended
    template: centralservices/r53-zone.cf.yaml           # CF template relative to cloudformation directory
    parameters:                                          # Parameters to the CF stack
      ManagedZoneDomainName: in.cld
      ManagingAccountArns:                               # List parameters turn into comma-separated values
        - arn:aws:iam::000000000000:root
        - arn:aws:iam::111111111111:root
        - arn:aws:iam::222222222222:root

  - name: in-cld-provisioning                            # name of CF stack, INSTALLATION_NAME will be prepended
    template: centralservices/r53-provisioning.cf.yaml   # CF template relative to cloudformation directory
    parameters:
      LambdaSourceS3Key: !LambdaZip provisionR53.zip     # points to the lambda function under src/provisionR53 (read below)
      SharedServiceR53ZoneRoleArn: !StackOutput in-cld-managed-zone.ManagedZoneCrossAccountRole    # will take the output called ManagedZoneCrossAccountRole from the above stack called in-cld-managed-zone
      Route53DomainName: !StackOutput in-cld-managed-zone.ManagedZoneDomainName
      ExportOutputs: 'false'                             # put numbers and booleans in quotes

  # Self-managed stackset

  - name: centralservices-iam-set
    type: stackset                                       # set type to stackset
    template: sets/iam.cf.yaml
    parameters:                                          # parameters to the StackSet
      SSMLogsLambdaS3Key: !LambdaZip ssmLogsConfig.zip
      SAMLUsername: *SAML_USERNAME
      SAMLProviderName: *SAML_PROVIDER_NAME
    pilot:                                               # when StackSet is updated only update instances in these accounts
      accounts:
        - '000000000000'
    rollout_strategy: accounts                           # set to organization for AWS Organisation-managed stackset
    rollout:                                             # manage StackSet instances
      - account: '000000000000'
        override:                                        # parameter override
          Route53ZoneDomain: prod.innablr.lan
      - account: '111111111111'
        regions:                                         # in this account it goes into two regions
          - ap-southeast-2
          - eu-west-1
        override:
          Route53ZoneDomain: preprod.innablr.lan
      - account: '222222222222'
        override:
          Route53ZoneDomain: dev.innablr.lan
      - account: '999999999999'
        regions: []                                      # this is how you delete an instance
        override:
          Route53ZoneDomain: dontwant.innablr.lan

  # Stackset managed by the AWS Organization

  - name: centralservices-org-iam-set
    type: stackset                                       # set type to stackset
    template: sets/iam.cf.yaml
    parameters:                                          # parameters to the StackSet
      SSMLogsLambdaS3Key: !LambdaZip ssmLogsConfig.zip
      SAMLUsername: *SAML_USERNAME
      SAMLProviderName: *SAML_PROVIDER_NAME
    call_as: self                                        # delegated_admin is also supported
    rollout_strategy: organization
    rollout_autodeploy:
      enable: true
      retain_on_removal: false
    rollout:                                             # manage StackSet instances
      - ou: ou-xxxx-xw09483h
        override:                                        # parameter override
          Route53ZoneDomain: prod.innablr.lan
      - ou: ou-xxxx-u49ogrw9
        regions:                                         # in this account it goes into two regions
          - ap-southeast-2
          - eu-west-1
        override:
          Route53ZoneDomain: preprod.innablr.lan
      - ou: ou-xxxx-rj3kl2ur
        override:
          Route53ZoneDomain: dev.innablr.lan
      - ou: ou-xxxx-h3kj57gk
        regions: []                                      # this is how you delete an instance
        override:
          Route53ZoneDomain: dontwant.innablr.lan

Automated Lambda functions

If your deployment contains Lambda function they can be handled by the Seed automatically. In the examples directory you can find an example of a Lambda function called kmsParameters

1. Create a directory under src for your Lambda, say kmsParameters
2. Do the development
3. Create a Makefile in the directory you have created and make sure that the default target of the Makefile produces a zip-file, say kmsParameters.zip
4. In your runtime environment configuration use !LambdaZip kmsParameters.zip to pass the zip-file name to the CloudFormation template (see the example above)

If your Lambda function is used in a StackSet and needs to be available from other AWS accounts make sure that you give access to the Seed bucket from those accounts. Refer to the stack bucket-policy.cf.yaml that is included in the examples.

Instead you can specify your AWS Organization ARN on the Seed command line using the -o parameter and the bucket will be shared to the entire AWS Organization automatically.

Arbitrary artifacts

If you want to include any configuration objects for your software or other relatively lightweight artifacts you can create a directory called config/<runtime_environment> under the root of your project and anything you put in this directory will be uploaded in the Seed S3 bucket under a key called config.

Let's say you have config/dev/myapp_cert.pem and you deploy a runtime configuration called dev. The file will be uploaded in the bucket as config/myapp_cert.pem.

Configuration tags

In the environment configuration you can use the following tags in stack parameters specification:

1. !IncludeAll [concat, tenants/*.yaml] - will include all files by the specified wildcard. You may either choose to concat and you will get a list as a result, or merge and get a dict

2. !ObjectPath [*CONFIG_OBJECT, '$.stacks."test-stack"'] - runs an ObjectPath expression on the specified data structure

3. !LambdaZip kmsParameters.zip - will pass the correct S3 key to the uploaded kmsParameters.zip, so you can use it in your Lambda resources together with TemplatesS3Bucket

4. !CloudformationTemplateS3Key support/bucket-policy.cf.yaml - works very similar to !Lambdazip but for Cloudformation templates. Will pass down the correct S3 key to the specified CloudFormation stack. You can use it for managing nested stacks.

5. !CloudformationTemplateS3Url support/bucket-policy.cf.yaml - similar to the above, but contains the full S3 URL of the specified template.

6. !StackOutput stack-name.OutputName - will read the corresponding output from the specified stack and pass it down here. The stack needs to have been created above in the sequence.

7. !Builtin TemplatesS3Bucket - returns the value of a builtin parameter. This allows you to pass the builtin Seed parameters like TemplatesS3Bucket as different Cloudformation parameter names should you need to do so.

8. !EnvironmentVariable DOMAIN_NAME - returns the value of an environment variable. If the variable is not set the deployment will abort.

9. !SSMParameterDirect - reads the value of the specified SSM parameter prefixed with /product_name/installation_name/ from SSM and pushes it into the Cloudformation stack

10. !SSMParameterDeclared - instead of reading the SSM parameter value this directive will construct its name prefixed with /product_name/installation_name/ and pass it down to the Cloudformation stack, so you can use Cloudformation native SSM parameter handling

11. !ArtifactVersion, !ArtifactRepo and !ArtifactImage - these three tags are used together with a release manifest in release management

Release management

cloudformation-seed also can read a release manifest file if you specify it in the -m commandline argument. Release manifest contains artifact names, their versions and other information about the software that is being deployed by the Seed. You can then inform your Cloudformation stacks about the versions and images you are deploying using the !ArtifactVersion, !ArtifactRepo and !ArtifactImage tags in the runtime environment configuration.

More documentation about release management is coming soon.