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:
- UI built-in
- Deploy your own functions or from the Function Store
- Instrumentation via Prometheus
- Autoscaling via AlertManager
- REST API available
Pictured: conceptual architecture when Kubernetes is used as the orchestration provider
REST 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-IdWithin 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. |