Configuring Lambda Function Services with flightcontrol.json

In addition to the Service Configuration attributes that are common to all services, the following attributes are specific to lambda function services.

Lambda Function Service Attributes

The type for all private web services is lambda-function, and should be specified like the following:

type: 'lambda-function'

Lambda Config

lambda: object

• Example:

"lambda": {
  "memory": 128,
  "storage": 512,
  "cpuArchitecture": "x86_64",
  "packageType": "zip",
  "fnUrl": {
    "enabled": false,
  },
  "timeoutSecs": 3,
  "tracing": true
}

Memory

lambda.memory: number

• Example: "lambda": {"memory": "512"}
• The memory configuration for lambda, supports values in MB only.
• Supported values are between 128 - 10,240 (10GB).

Storage

lambda.storage: number

• Example: "lambda": {"storage": "512"}
• The storage available in the /tmp directory to Lambda runtime in MB.
• This storage is cleared out after the function execution.
• Supported values between 512 and 10,240 (10GB).

CPU Architecture

lambda.cpuArchitecture: 'x86_64' | 'arm64'

• Example: "lambda": {"cpuArchitecture": "x86_64"}
• Depending on your dependency, arm64 is probably the right choice, as it offers better performance for general workloads and lower pricing.

Package Type

lambda.packageType: "zip" | "docker"

• Example: "lambda": {"packageType": "zip"}
• Lambda zip supports a maximum of 250MB of unzipped code including depdencies and layers, cold starts increases with package size.
• Lambda container (docker) supports up to 10GB images, docker lambda has slower cold starts compared to zip but usually consistent even with bigger images.

Timeout

lambda.timeoutSecs: number

• Example: "lambda": {"timeoutSecs": 600}
• The timeout in seconds for each execution.
• Supported values between 1 and 900 (15 minutes).

Reserved Concurrency

lambda.reservedConcurrency: number

• Example: "lambda": {"reservedConcurrency": 1}
• Reserved maximum concurrency allocated to Lambda. Taken from total concurrency units allowed for Lambdas across the region, which by default is 1000.
• A low number can cause throttling, a high number can cause other Lambdas to be throttled. For example if your quota is 1,000 and you set one Lambda reserved concurrency to 1,000, no other Lambdas will be able to run.
• Supported values between 0 and 900, 0 meaning no traffic allowed.

Tracing

lambda.tracing: boolean

• Example: "lambda": {"tracing": true}
• Enables AWS X-Ray tracing for the lambda function.
• Required to see advanced metrics in AWS console like cold start statistics

VPC

lambda.vpc: boolean

• Example: "lambda": {"vpc": true}
• Places the Lambda function inside the environment VPC
• Will incur +$32/mo for a NAT gateway if the environment doesn’t already have one

Function URL

lambda.fnUrl: object

• Example: "lambda": {"fnUrl": {"enabled": false}}
• The configuration related to the lambda function URL.

Extra options for fnURL

• Example:

"fnUrl": {
  "enabled": true,
  "invokeMode": "ResponseStream",
  "authType": "None",
  "cors": {
    "allowCredentials": false,
    "allowHeaders": [],
    "allowMethods": ["*"],
    "allowOrigin": ["*"],
    "maxAge": 0,
    "exposedHeaders": [],
  }
}

• enabled - Boolean, whether the function URL is enabled or not.
• invokeMode - Whether Lambda streams the response ResponseStream back to requestor, or buffers Buffered the whole response till the end of execution. Optional, with default value Buffered.
• authType - Whether the requestor should authenticate with IAM Iam or not None. Optional, with default value None.
• cors.allowCredentials - Boolean, whether to allow cookies or other credentials in requests or not. Optional, default is false.
• cors.allowHeaders - Array of HTTP headers that requestor can include in the request to Lambda. Optional, with default value [].
• cors.allowMethods - Array of HTTP methods that the requestor can use while triggering the lambda. Optional with default value to allow methods ["*"].
• cors.allowOrigin - Array of origins that can request the Lambda. Optional, with default value to allow all origins ["*"].
• cors.maxAge - maxAge in seconds that the browsers can cache the response from Lambda. Optional, with default value to disable cache 0.
• cors.exposedHeaders - Array of HTTP headers that are allowed to be exposed while responding to the origin. Optional, with default value of empty array, not allowing any headers [].

Extra options

versionHistoryCount: number

• Example: "versionHistoryCount": 15
• Optional with default: 10, maximum value: 75
• The number of versions to keep in the version history for rollback

Extra options for Nixpacks & Legacy Node.js

basePath?: string (only supported when buildType: nixpacks)

• Allows you to specify in which folder the commands should run
• Example: "basePath": "./apps"
• Optional, defaults to ”./”

installCommand: string

• Example: "installCommand": "./install.sh"
• Optional, intelligent default based on your language and framework detected at the basePath
• What we use to install dependencies for your build

buildCommand: string

• Example: "buildCommand": "blitz build"
• Optional, intelligent default based on your language and framework detected at the basePath
• What we use to build your app

postBuildCommand: string

• Example: "postBuildCommand": "./postBuildCommand.sh"
• Optional, Empty by Default
• Used as a build hook to run any operation after your build is complete

preDeployCommand: Array<string>

• Example: "preDeployCommand": ["bundle", "exec", "rails", "db:prepare"],
• Optional
• A command that runs after successful build and before starting the deploy (more information).
• If configured, a dedicated container is started to run the command and shuts down on completion.
• The command must be split into array parts because this is used to override the Docker CMD, and if passed as a single string runc counts it as a single command instead of a command + arguments.
• Note: using this for database migrations will add 2-3 minutes to your deploy time because of the time it takes this temporary container to boot and run.

outputDirectory: string

• Example: "outputDirectory": "./dist"
• Required when package type is zip. Ignored when package type is image. This entire directory will be zipped and deployed to the Lambda.
• If build type is Nixpacks:
  • Set to relative path from configured base path to the directory of the Lambda handler file
• If build type is Dockerfile:
  • Set to absolute path of the Lambda handler directory within the built image. If WORKDIR is set to /app and the Lambda handler is in dist, then set to /app/dist.

startCommand: string

• Example: "startCommand": "blitz start"
• Optional, intelligent default based on your language and framework detected at the basePath
• What we use to start your app

postDeployCommand: Array<string>

• Example: "postDeployCommand": ["node", "script.js"]
• Optional
• A command that runs after successful deploy (more information).
• If configured, a dedicated container is started to run the command and shuts down on completion.
• The command must be split into array parts because this is used to override the Docker CMD, and if passed as a single string runc counts it as a single command instead of a command + arguments.

Extra options for custom Dockerfile only

dockerfilePath: string

• Example: "dockerfilePath": "packages/private web/Dockerfile"
• Relative path to the Dockerfile from your repo root
• It’s recommended to use ENTRYPOINT instead of CMD for your start command
• You can authenticate with Docker Hub by adding your Docker Hub credentials as DOCKER_USERNAME and DOCKER_PASSWORD environment variables. If these env variables are present, we’ll run docker login with them. This will prevent Docker Hub rate limit issues.

dockerContext: string

• Example: "dockerContext": "packages/private web"
• Optional with default: "." (repo root)
• Relative path to the docker context from the repo root
• It’s recommended to use ENTRYPOINT instead of CMD for your start command

injectEnvVariablesInDockerfile: boolean

• Example: "injectEnvVariablesInDockerfile": false
• Optional with default: true
• Whether to inject environment variables automatically into Dockerfile or not
• It’s recommended to use Docker build secrets to control how environment variable are used during build, check the guide here