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84 lines
4.4 KiB
Markdown
84 lines
4.4 KiB
Markdown
# Gateway
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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.
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The gateway will scale functions according to demand by altering the service replica count in the Kubernetes API. Custom alerts generated by AlertManager are received on the /system/alert endpoint.
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In summary:
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* Built-in UI Portal
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* Deploy functions from the Function Store or deploy your own
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* Instrumentation via Prometheus
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* Auto-scaling via AlertManager and Prometheus
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* Scaling up from zero
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* REST API available documented with Swagger
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*Pictured: conceptual architecture when Kubernetes is used as the orchestration provider*
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## Function Providers
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Providers for functions can be written using the [faas-provider](https://github.com/openfaas/faas-provider/) interface in Golang which provides the REST API for interacting with the gateway.
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## REST API
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Swagger docs: https://github.com/openfaas/faas/tree/master/api-docs
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## CORS
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By default the only CORS path allowed is for the Function Store which is served from the GitHub RAW CDN.
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## UI Portal
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The built-in UI Portal is served through static files bound at the /ui/ path.
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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.
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View the source in the [assets](./assets/) folder.
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### Function Store
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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](https://github.com/openfaas/faas-cli).
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See the [openfaas/store](https://github.com/openfaas/store) repo for more.
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## Logs
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Logs are available at the function level via the API.
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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.
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## Tracing
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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.
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Header:
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```
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X-Call-Id
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```
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Within a function this is available as `Http_X_Call_Id`.
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## Environmental overrides
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The gateway can be configured through the following environment variables:
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| Option | Usage |
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|------------------------|--------------|
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| `write_timeout` | HTTP timeout for writing a response body from your function (in seconds). Default: `8` |
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| `read_timeout` | HTTP timeout for reading the payload from the client caller (in seconds). Default: `8` |
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| `functions_provider_url` | URL of upstream [functions provider](https://github.com/openfaas/faas-provider/) - i.e. Swarm, Kubernetes, Nomad etc |
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| `logs_provider_url` | URL of the upstream function logs api provider, optional, when empty the `functions_provider_url` is used |
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| `faas_nats_address` | The host at which NATS Streaming can be reached. Required for asynchronous mode |
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| `faas_nats_port` | The port at which NATS Streaming can be reached. Required for asynchronous mode |
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| `faas_nats_cluster_name` | The name of the target NATS Streaming cluster. Defaults to `faas-cluster` for backwards-compatibility |
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| `faas_nats_channel` | The name of the NATS Streaming channel to use. Defaults to `faas-request` for backwards-compatibility |
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| `faas_prometheus_host` | Host to connect to Prometheus. Default: `"prometheus"` |
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| `faas_prometheus_port` | Port to connect to Prometheus. Default: `9090` |
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| `direct_functions` | `true` or `false` - functions are invoked directly over overlay network by DNS name without passing through the provider |
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| `direct_functions_suffix` | Provide a DNS suffix for invoking functions directly over overlay network |
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| `basic_auth` | Set to `true` or `false` to enable embedded basic auth on the /system and /ui endpoints (recommended) |
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| `secret_mount_path` | Set a location where you have mounted `basic-auth-user` and `basic-auth-password`, default: `/run/secrets/`. |
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| `scale_from_zero` | Enables an intercepting proxy which will scale any function from 0 replicas to the desired amount |
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