Details
The Overview walked through a simple “Hello World” example. In this section we’ll cover how Sparta works in preparation for moving on to more advanced use. Most development will use the provision
command line argument, so this section will outline exactly what that entails.
Provisioning Flow
The provisioning workflow is defined in provision.go, with a goal of marshalling all AWS operations into a CloudFormation template. Where CloudFormation does not support a given service, Sparta falls back to using Lambda-backed Custom Resources in the template definition.
At a high level, provisioning uses the flow below. We’ll dive a bit deeper into each stage in the following sections.
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Verify Static IAM Roles
The HandleAWSLambda
function accepts either a string
or a sparta.IAMRoleDefinition
value type. In the event that a string is passed, this function verifies that the IAM role exists and builds up a cache of IAM role information that can be shared and referenced during template generation. Specifically, a pre-existing IAM Role ARN is cached to minimize AWS calls during template generation.
Compile
The next step is to cross compile the application to a binary that can be executed on an AWS Lambda instance. The default compile flags are:
- TAGS:
-tags lambdabinary
- ENVIRONMENT:
GOOS=linux GOARCH=amd64
The build output is created in the _./.sparta/ working directory. The full set of build flags is available by running the provision workflow with the --level debug
option.
Package
The end result of the package phase is a ZIP archive of your application. You can inspect this archive, as well as any other Sparta artifacts in the ./.sparta directory by supplying the --noop
argument during a provision operation.
Upload Archive To S3
Uploads the archive to S3. There’s not much else to see here.
Generate CloudFormation Template
Uploading the archive produces a valid CodeURI value that can be used for Lambda function creation. The CloudFormation template is generated by marshaling the sparta.LambdaAWSInfo
objects into CloudFormation JSON representations.
The AWS Lambda marshaling is automatically handled. This is also the point at which the optional TemplateDecorator functions are called to annocate the automatically generated template with additional resources.
Upload CloudFormation Template to S3
Uploads the template to S3 to maximize template size. There’s not much else to see here.
Create/Update Stack
Finally, the provisioning workflow determines whether the Sparta serviceName
exists and either creates or updates as appropriate using CloudFormation APIs.
Next Steps
Now that we’ve covered how Sparta handles provisioning your stack, we’re ready to expand functionality to leverge more of the AWS ecosystem in the next section.