Using dependencies in your functions

All Functional Web Apps have project level dependencies and function level dependencies. Project level dependencies are defined at the root of the project. Lambda functions within a project are deployed individually and subsequently need to package their own dependencies. Different deployment frameworks handle this in different ways depending on the runtime; Architect projects encourage single responsibility functions with the minimum number of dependencies. This intentional isolation leads to easier debugging, faster coldstart and least privilege security.

Node.js

If there is a package.json in the Lambda function folder it will be used. If there is no package.json in the function folder Architect will statically analyze the code and transparently tree shake an optimal node_modules folder for that specific Lambda function. Imported code must be in a package.json file or relative to the root of the function and or the module will not load once it has been deployed!

For example, assuming the current directory is src/http/get-index:

// this is ok if it exists in package.json
let arc = require('@architect/functions')

// this will fail
let foo = require('../foo')

// this will work
let foo = require('./foo')

// this is also ok (if foo exists in @shared)
let foo = require('@architect/shared/foo')

Recommended additional reading for working with the Node runtime:

Ruby

Architect uses Gemfile and Gemfile.lock with bundle to ensure Lambda function dependencies are deterministic. Code must be relative to the root of Lambda function directory.

require 'bundler/setup' # initialize Bundler

require 'architect/functions' # is ok if it is vendored in the Lambda folder
require '../foo' # this will fail
require './foo' # this will work
require './vendor/shared/foo' # this is also ok (if foo exists in @shared)

Install runtime helpers for Ruby:

cd path/to/lambda
bundle init
bundle config set --local path 'vendor/bundle'
bundle add architect-functions

Deployment Configuration

Prior to deploying, it is recommended to configure Bundler to work in a Lambda environment.

You’ll need to let Bundler know about Lambda’s platform architecture by adding an entry to the Gemfile.lock. Additionally, Bundler often tries to write to the filesystem at runtime. Freeze the bundle by setting the BUNDLE_FROZEN environment variable to 1.

bundle lock --add-platform x86_64-linux # declare Lambda's platform
npx arc env staging BUNDLE_FROZEN 1 # use arc to set an env var
npx arc env production BUNDLE_FROZEN 1 # do the same for production

Python

Architect uses requirements.txt with pip3 to ensure Lambda function dependencies are deterministic. Code must be relative to the root of Lambda function directory.

import arc # is ok if it is vendored in the Lambda folder
import ..foo # this will fail
import .foo # this will work
import vendor.shared.foo # this is also ok (if foo exists in @shared)

Install runtime helpers for Python:

cd path/to/lambda
pip install --target ./vendor architect-functions
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