title: Human Guide description: How to use @lastshotlabs/slingshot-infra for platform and deployment configuration

@lastshotlabs/slingshot-infra is the package for describing and operating infrastructure around Slingshot apps. Use it when you want typed config for stacks, shared resources, deployment plans, and environment-specific infrastructure behavior.

When To Use It

Reach for this package when:

• you want slingshot.platform.ts and slingshot.infra.ts instead of ad hoc deployment metadata
• you have multiple services or environments and want the infrastructure shape captured in code
• you want to compute deploy plans, scaffold infra files, or inspect which shared resources an app uses

You probably do not need this package to boot a local app. This is deployment and platform tooling, not runtime request handling.

The Two Files It Centers Around

Most usage comes down to two files:

slingshot.platform.ts

Shared platform definition for the repo or environment family.

This is where you define:

• org and cloud provider
• region
• shared resources
• stages such as dev and prod
• stack presets such as ECS or EC2+Nginx

slingshot.infra.ts

App-level or service-level infrastructure declaration.

This is where you define:

• which stacks the app deploys to
• container size and scaling
• health check behavior
• which shared resources the app consumes
• service splits for multi-service apps

Minimal Platform File

import { definePlatform } from '@lastshotlabs/slingshot-infra';

export default definePlatform({
  org: 'acme',
  provider: 'aws',
  region: 'us-east-1',
  registry: {
    provider: 'local',
    path: '.slingshot/registry.json',
  },
  stages: {
    dev: {
      env: { NODE_ENV: 'development' },
    },
    prod: {
      env: { NODE_ENV: 'production' },
    },
  },
  stacks: {
    main: { preset: 'ecs' },
  },
  defaults: {
    preset: 'ecs',
    scaling: { min: 1, max: 3, cpu: 256, memory: 512 },
    logging: { driver: 'cloudwatch', retentionDays: 30 },
  },
});

Minimal App Infra File

import { defineInfra, deriveUsesFromAppConfig } from '@lastshotlabs/slingshot-infra';

const appConfig: Record<string, unknown> = {
  db: { provider: 'postgres' },
  jobs: {},
};

export default defineInfra({
  stacks: ['main'],
  port: 3000,
  size: 'small',
  uses: deriveUsesFromAppConfig(appConfig),
  healthCheck: '/health',
});

That deriveUsesFromAppConfig() helper is useful when you want infra declarations to stay aligned with the app config instead of hand-maintaining the uses list.

Common Workflows

1. Define infra in code

Use definePlatform() and defineInfra() for typed config with validation and frozen outputs.

2. Load config files

Use loadPlatformConfig() and loadInfraConfig() when a CLI or deployment tool needs to discover slingshot.platform.ts and slingshot.infra.ts.

3. Plan deploys

Use computeDeployPlan() and formatDeployPlan() when you want to show what will happen before a deploy actually runs.

4. Run deploys and rollbacks

Use runDeployPipeline() and runRollback() when you are wiring an operational flow around Slingshot infra config.

5. Start from scaffolds

Use generatePlatformTemplate() and generateInfraTemplate() when you want to create starter files instead of hand-writing them from scratch.

Multi-Service Shape

If one app becomes multiple deployable units, defineInfra() supports services instead of only a single top-level service.

That is the right time to move from:

• one service with stacks, port, and uses

to:

• api, ws, jobs, or other named services with separate stack and scaling settings

What This Package Is Not

This package does not add routes, middleware, auth, or app runtime behavior.

It exists to answer questions like:

• what resources does this app consume?
• which stack should this service deploy to?
• what is the scaling and health-check shape for this stage?
• how do we compute and execute a deploy plan consistently?

Gotchas

• loadPlatformConfig() looks for slingshot.platform.ts upward from the starting directory unless SLINGSHOT_PLATFORM is set.
• loadInfraConfig() looks for slingshot.infra.ts in the target directory.
• TypeScript infra config files require Bun runtime when loaded directly.
• If you only need a single small app locally, this package can be overkill on day one. It starts paying off when shared resources, multiple services, or deployment automation become real concerns.

Key Files

• packages/slingshot-infra/src/index.ts
• packages/slingshot-infra/src/config/platformSchema.ts
• packages/slingshot-infra/src/config/infraSchema.ts
• packages/slingshot-infra/src/config/deriveUsesFromApp.ts
• packages/slingshot-infra/src/deploy/pipeline.ts
• packages/slingshot-infra/src/scaffold/