gateway

README

Gateway

The API Gateway provides an external route into your functions and collects Cloud Native metrics through Prometheus. The gateway also has a UI built-in which can be used to deploy your own functions or functions from the OpenFaaS Function Store then invoke them.

The gateway will scale functions according to demand by altering the service replica count in the Docker Swarm or Kubernetes API. Custom alerts generated by AlertManager are received on the /system/alert endpoint.

In summary:

• Built-in UI Portal
• Deploy functions from the Function Store or deploy your own
• Instrumentation via Prometheus
• Auto-scaling via AlertManager and Prometheus
• Scaling up from zero
• REST API available documented with Swagger

Pictured: conceptual architecture when Kubernetes is used as the orchestration provider

Function Providers

Providers for functions can be written using the faas-provider interface in Golang which provides the REST API for interacting with the gateway. The gateway originally interacted with Docker Swarm directly and anything else via a Function Provider - this support was moved into a separate project faas-swarm.

REST API

Swagger docs: https://github.com/openfaas/faas/tree/master/api-docs

CORS

By default the only CORS path allowed is for the Function Store which is served from the GitHub RAW CDN.

UI Portal

The built-in UI Portal is served through static files bound at the /ui/ path.

The UI was written in Angular 1.x and makes uses of jQuery for interactions and the Angular Material theme for visual effects and components.

View the source in the assets folder.

Function Store

The Function Store is rendered through a static JSON file served by the GitHub RAW CDN. The Function Store can also be used via the OpenFaaS CLI.

See the openfaas/store repo for more.

Logs

Logs are available at the function level and can be accessed through Swarm or Kubernetes using native tooling. You can also install a Docker logging driver to aggregate your logs. By default functions will not write the request and response bodies to stdout. You can toggle this behaviour by setting read_debug for the request and write_debug for the response.

Tracing

An "X-Call-Id" header is applied to every incoming call through the gateway and is usable for tracing and monitoring calls. We use a UUID for this string.

Header:

X-Call-Id

Within a function this is available as Http_X_Call_Id.

Environmental overrides

The gateway can be configured through the following environment variables:

Option	Usage
write_timeout	HTTP timeout for writing a response body from your function (in seconds). Default: 8
read_timeout	HTTP timeout for reading the payload from the client caller (in seconds). Default: 8
functions_provider_url	URL of upstream functions provider - i.e. Swarm, Kubernetes, Nomad etc
faas_nats_address	Address of NATS service. Required for asynchronous mode
faas_nats_port	Port for NATS service. Requrired for asynchronous mode
faas_prometheus_host	Host to connect to Prometheus. Default: "prometheus"
faas_promethus_port	Port to connect to Prometheus. Default: 9090
direct_functions	true or false - functions are invoked directly over overlay network by DNS name without passing through the provider
direct_functions_suffix	Provide a DNS suffix for invoking functions directly over overlay network
basic_auth	Set to true or false to enable embedded basic auth on the /system and /ui endpoints (recommended)
secret_mount_path	Set a location where you have mounted basic-auth-user and basic-auth-password, default: /run/secrets/.
scale_from_zero	Enables an intercepting proxy which will scale any function from 0 replicas to the desired amount