ARM64

skuba templates are configured to be built and run on ARM64 hardware in CI/CD.

This topic provides some context around this decision, then discusses how you can get ready for ARM64 and adopt it across new and existing projects.

Background

SEEK traditionally ran its compute workloads on AMD64 (x86-64) hardware, with Intel as the de facto choice across home and server computing. Our recommendation has since shifted to ARM64 hardware, with the proliferation of ARM-based alternatives in local and cloud environments providing access to greater cost efficiency.

On AWS’ cloud platform, this means Graviton-based instances rather than Intel-based or AMD-based ones.

Getting ready for ARM64

If you’d like to build and run your projects on ARM64 hardware, create a Buildkite cluster with a Graviton-based instance type. In a vCurrent strategy:

  schemaVersion: vCurrent
  clusters:
    - name: cicd # Existing cluster
      
      instanceType: t3.large
      rootVolumeSize: 8
      
      # ...
+   
+   - name: graviton # New cluster; choose a name you like
+     
+     cpuArchitecture: arm64
+     instanceType: t4g.large # Required; g is for Graviton
+     rootVolumeSize: 8 # Optional
+     
+     # ...

Repeat this process for all accounts and strategies under your remit, taking care to right-size instances and volumes in the process. If the existing cluster is already optimised, simply map instanceType to the Graviton equivalent and reuse rootVolumeSize.

This approach allows you to gradually migrate existing projects over to the new clusters, then delete the original clusters once complete:

  schemaVersion: vCurrent
  clusters:
-   - name: cicd
-
-     instanceType: t3.large
-     rootVolumeSize: 8
-
-     # ...
-
    - name: graviton

      cpuArchitecture: arm64
      instanceType: t4g.large
      rootVolumeSize: 8

      # ...

See Builds at SEEK and the Gantry ARM reference for more information.

Creating a new project

Defaulting to ARM64

Let’s start by following the skuba init documentation:

skuba init

and reaching the starter questions:

? For starters, some project details:
⊙          Owner : SEEK-Jobs/my-team
⊙           Repo : my-repo
⊙       Platform : arm64
⊙ Default Branch : main

# ...

Note that new projects default to the arm64 platform; leave this as is.

Continue to follow the prompts. Your Buildkite pipeline should point to the new cluster(s) configured above. After initialising your project, review the agents.queues in .buildkite/pipeline.yml:

agents:
  queue: my-prod-account:graviton # Should be the new name you chose above

steps:
  - label: Prod

  - label: Dev
    agents:
      queue: my-dev-account:graviton # Should be the new name you chose above

At this point, your new project is ready for ARM64.

Reverting to AMD64

If you later realise that you are not ready to build and run on ARM64 hardware, you can revert your project to be compatible with AMD64 hardware.

Point your agents.queues back to the original cluster(s) in pipeline.yml:

  agents:
-   queue: my-prod-account:graviton
+   queue: my-prod-account:cicd

  steps:
    - label: Prod

    - label: Dev
      agents:
-       queue: my-dev-account:graviton
+       queue: my-dev-account:cicd

Replace the relevant --platform flags in your Dockerfile(s):

- FROM --platform=arm64 node:20-alpine AS dev-deps
+ FROM --platform=amd64 node:20-alpine AS dev-deps

- FROM --platform=arm64 gcr.io/distroless/nodejs20-debian12 AS runtime
+ FROM --platform=amd64 gcr.io/distroless/nodejs20-debian12 AS runtime

For a Gantry service, modify cpuArchitecture property on the ContainerImage and Service resources in gantry.build.yml and gantry.apply.yml:

  kind: ContainerImage
  
  schemaVersion: v0.0
  
- cpuArchitecture: arm64
+ cpuArchitecture: amd64
  
  ...

  kind: Service
  
  schemaVersion: v0.0
  
- cpuArchitecture: arm64
+ cpuArchitecture: amd64
  
  ...

For an AWS CDK worker, modify the architecture property on the Lambda function resource in infra/appStack.ts:

  const worker = new aws_lambda.Function(this, 'worker', {
-   architecture: aws_lambda.Architecture.ARM_64,
+   architecture: aws_lambda.Architecture.X86_64,
  });

For a Serverless worker, modify the provider.architecture property in serverless.yml:

  provider:
-   architecture: arm64
+   architecture: x86_64

Migrating an existing project

This guide is targeted at existing TypeScript projects that are looking to migrate from AMD64 to ARM64.

In your Buildkite pipeline(s), point your agents.queues to the new cluster(s) you configured above. Your default pipeline should be defined in .buildkite/pipeline.yml, though you may have auxiliary pipelines under a similar or nested directory.

  agents:
-   queue: my-prod-account:cicd
+   queue: my-prod-account:graviton # Should be the new name you chose above

steps:
  - label: Prod

  - label: Dev
    agents:
-     queue: my-dev-account:cicd
+     queue: my-dev-account:graviton # Should be the new name you chose above

Set the --platform=arm64 flag on each external FROM command in your Dockerfile(s):

- FROM node:20-alpine AS dev-deps
+ FROM --platform=arm64 node:20-alpine AS dev-deps

- FROM gcr.io/distroless/nodejs20-debian12 AS runtime
+ FROM --platform=arm64 gcr.io/distroless/nodejs20-debian12 AS runtime

Review and test the behaviour of your project dependencies that use platform-specific binaries. Common examples include:

Browser-adjacent packages like puppeteer
Cryptographic packages like bcrypt
Low-level tooling like esbuild

Gantry

For a Gantry service, first locate your Gantry resource files. As these have no set naming convention, you can look for:

YAML files that match the following common patterns:
- .gantry/**/*.{yaml,yml}
- gantry.{yaml,yml}
- gantry.apply.yml
- gantry.build.yml
- service.{yaml,yml}

files supplied to the Gantry plugin in your Buildkite pipeline:

steps:
  - label: 📦 Build & Package
    plugins:
      - *aws-sm
      - *private-npm
      - *docker-ecr-cache
      - seek-jobs/gantry#v3.0.0:
          command: build
          file: gantry.build.yml # <-- here
          region: ap-southeast-2
          values: .gantry/common.yml

Once you have located these files, set the cpuArchitecture property on the ContainerImage and Service resources:

  kind: ContainerImage
  
  schemaVersion: v0.0
  
+ cpuArchitecture: arm64
  
  ...

  kind: Service
  
  schemaVersion: v0.0
  
+ cpuArchitecture: arm64
  
  ...

AWS CDK

For an AWS CDK worker, first locate your application stack. This is a TypeScript source file that may be named similar to infra/appStack.ts and contains a class that extends Stack:

export class AppStack extends Stack {
  constructor(scope: Construct, id: string, props?: StackProps) {
    // ...
  }
}

Once you have located this file, set the architecture property on the Lambda function resource:

  const worker = new aws_lambda.Function(this, 'worker', {
+   architecture: aws_lambda.Architecture.ARM_64,
    runtime: aws_lambda.Runtime.NODEJS_20_X,
    // ...
  });

  const worker = new aws_lambda_nodejs.NodejsFunction(this, 'worker', {
+   architecture: aws_lambda.Architecture.ARM_64,
    runtime: aws_lambda.Runtime.NODEJS_20_X,
    // ...
  });

Serverless

For a Serverless worker, set the provider.architecture property in serverless.yml:

  provider:
    name: aws
    
+   architecture: arm64
    runtime: nodejs20.x
    
    ...