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Overview

Applad functions run in isolated Docker containers and support multiple runtimes: Dart, Node.js, Python, Go, PHP, Ruby, and more. Each function is defined in a single YAML file with a source block pointing to your code.

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Defining Functions

Each function lives in functions/<name>.yaml.

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Basic Function Structure

functions/send-welcome-message.yaml
name: "send-welcome-message"
runtime: "dart"
timeout: 30
memory: "256mb"

source:
  type: "local"
  path: "./src/functions/send-welcome-message/main.dart"

container:
  readonly_filesystem: true
  no_new_privileges: true
  network: "restricted"
  allowed_hosts:
    - "api.resend.com"

triggers:
  - type: "event"
    event: "auth.user.created"

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Supported Runtimes

  • dart
  • node
  • python
  • go
  • php
  • ruby
  • Custom containers via registry source

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Source Configuration

Functions can pull code from three source types:

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Local Source

source:
  type: "local"
  path: "./src/functions/send-welcome-message/main.dart"

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GitHub Repository

source:
  type: "github"
  repo: "myorg/myapp"
  branch: "main"
  path: "src/functions/process-payment/index.js"
  ssh_key: "ci-github-actions"

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Container Registry

source:
  type: "registry"
  image: "ghcr.io/myorg/send-welcome-message:latest"
  credentials: "ghcr-credentials"

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Trigger Types

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HTTP Trigger

triggers:
  - type: "http"
    method: "POST"
    path: "/payments/process"
    auth_required: true
    rate_limit:
      requests: 10
      window: "1m"
      per: "user"

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Event Trigger

triggers:
  - type: "event"
    event: "auth.user.created"
Common events:
  • auth.user.created
  • auth.user.updated
  • auth.user.deleted
  • payment.succeeded
  • payment.failed
  • Custom events from your application

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Scheduled Trigger

triggers:
  - type: "schedule"
    cron: "0 9 * * *"  # Daily at 9am
Cron syntax: minute hour day month weekday

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Webhook Functions

Inbound webhooks from third-party services (Stripe, GitHub, Twilio) use HTTP triggers with signature verification:
functions/handle-stripe-event.yaml
name: "handle-stripe-event"
runtime: "dart"
timeout: 30
memory: "256mb"

source:
  type: "github"
  repo: "myorg/myapp"
  branch: "main"
  path: "src/functions/handle-stripe-event/main.dart"
  ssh_key: "ci-github-actions"

container:
  readonly_filesystem: true
  no_new_privileges: true
  network: "restricted"
  allowed_hosts:
    - "api.stripe.com"

triggers:
  - type: "http"
    method: "POST"
    path: "/webhooks/stripe"
    auth_required: false  # Third-party services can't send session tokens
    verify:
      provider: "stripe"  # Built-in: stripe | github | twilio | generic
      secret: ${STRIPE_WEBHOOK_SECRET}

    # Optional: filter to specific event types
    events:
      - "payment_intent.succeeded"
      - "payment_intent.payment_failed"
      - "customer.subscription.deleted"

environment:
  - key: "STRIPE_WEBHOOK_SECRET"
    value: ${STRIPE_WEBHOOK_SECRET}

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Webhook Verification Providers

# Stripe
verify:
  provider: "stripe"
  secret: ${STRIPE_WEBHOOK_SECRET}

# GitHub
verify:
  provider: "github"
  secret: ${GITHUB_WEBHOOK_SECRET}
  header: "X-Hub-Signature-256"  # Default, can override

# Twilio
verify:
  provider: "twilio"
  secret: ${TWILIO_AUTH_TOKEN}

# Generic HMAC verification
verify:
  provider: "generic"
  secret: ${CUSTOM_WEBHOOK_SECRET}
  header: "X-Webhook-Signature"
  algorithm: "hmac-sha256"  # hmac-sha1 | hmac-sha256 | hmac-sha512

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Container Security

Functions run in hardened containers with security controls: 
container:
  readonly_filesystem: true   # Prevent writes to container filesystem
  no_new_privileges: true     # Prevent privilege escalation
  network: "restricted"       # Only allow specific hosts
  allowed_hosts:
    - "api.stripe.com"
    - "api.resend.com"

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Environment Variables

Pass secrets and configuration to functions: 
environment:
  - key: "STRIPE_SECRET"
    value: ${STRIPE_SECRET}
  - key: "API_ENDPOINT"
    value: "https://api.myapp.com"

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Cloud Burst

For heavy workloads, functions can burst to cloud compute:
functions/daily-report.yaml
name: "daily-report"
runtime: "python"
timeout: 300
memory: "1gb"

source:
  type: "github"
  repo: "myorg/myapp"
  branch: "main"
  path: "src/functions/daily-report/daily.py"
  ssh_key: "ci-github-actions"

cloud_burst:
  enabled: true
  provider: "aws"
  instance_type: "t3.large"
  region: "eu-west-1"
  credentials: "aws-production"
  max_duration: 3600

container:
  readonly_filesystem: false
  no_new_privileges: true
  network: "restricted"
  allowed_hosts:
    - "s3.eu-west-1.amazonaws.com"

triggers:
  - type: "schedule"
    cron: "0 9 * * *"
Applad provisions the VM, runs the container, and tears it down when done.

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Deploying Functions

1

List all functions

applad functions list
Shows runtime, source type, trigger type, and deployment status.
2

Deploy a function

applad functions deploy send-welcome-message
Applad:
  1. Fetches code from source
  2. Builds the container
  3. Scans for vulnerabilities
  4. Deploys to infrastructure
  5. Keeps previous version running until new one is healthy
3

View deployment logs

applad functions logs send-welcome-message
Streams execution logs in real time.

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Deploy all functions

applad functions deploy --all

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Testing Functions

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Invoke manually

applad functions invoke send-welcome-message

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Invoke with payload

applad functions invoke process-payment --data '{"amount": 1000}'
The function receives this as its event/request body.

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Building and Scanning

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Build without deploying

applad functions build send-welcome-message
Useful for catching build errors before deployment.

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Scan for vulnerabilities

applad functions scan send-welcome-message
Reports findings by severity. Runs automatically during deployment.

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Example: Complete Payment Function

functions/process-payment.yaml
name: "process-payment"
runtime: "node"
timeout: 60
memory: "512mb"

source:
  type: "github"
  repo: "myorg/myapp"
  branch: "main"
  path: "src/functions/process-payment/index.js"
  ssh_key: "ci-github-actions"

container:
  readonly_filesystem: true
  no_new_privileges: true
  network: "restricted"
  allowed_hosts:
    - "api.stripe.com"

triggers:
  - type: "http"
    method: "POST"
    path: "/payments/process"
    auth_required: true
    rate_limit:
      requests: 10
      window: "1m"
      per: "user"

environment:
  - key: "STRIPE_SECRET"
    value: ${STRIPE_SECRET}

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Example: Event-Triggered Function

functions/send-welcome-message.yaml
name: "send-welcome-message"
runtime: "dart"
timeout: 30
memory: "256mb"

source:
  type: "local"
  path: "./src/functions/send-welcome-message/main.dart"

container:
  readonly_filesystem: true
  no_new_privileges: true
  network: "restricted"
  allowed_hosts:
    - "api.resend.com"

triggers:
  - type: "event"
    event: "auth.user.created"

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Example: Scheduled Function

functions/daily-report.yaml
name: "daily-report"
runtime: "python"
timeout: 300
memory: "1gb"

source:
  type: "github"
  repo: "myorg/myapp"
  branch: "main"
  path: "src/functions/daily-report/daily.py"
  ssh_key: "ci-github-actions"

container:
  readonly_filesystem: false
  no_new_privileges: true
  network: "restricted"
  allowed_hosts:
    - "s3.eu-west-1.amazonaws.com"

triggers:
  - type: "schedule"
    cron: "0 9 * * *"  # Daily at 9am

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Next Steps

Deployments

Configure deployment pipelines for web, mobile, and desktop

Messaging

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