Gateway
The API Gateway provides an external route into your functions and collects Cloud Native metrics through Prometheus, as well as a UI for creating and invoking functions. The gateway will scale functions according to demand by altering the service replica count in the Docker Swarm or Kubernetes API.
Swagger docs: https://github.com/openfaas/faas/tree/master/api-docs
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 an alternate microservice to manage functions (e.g., Kubernetes). When given, this overrides the default Docker Swarm provider. |
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. |