Log Providers

OpenFaaS Gateway 0.15.0+ supports pluggable logging providers to support streaming function logs.

A log provider is an HTTP server that provides a /system/logs endpoint that supports a GET request with the following query parameters

• name : the function name and is required
• instance : the optional container name, that allows you to request logs from a specific function instance
• since : the optional datetime value to start the logs from
• tail : sets the maximum number of log messages to return, <=0 means unlimited
• follow : allows the user to request a stream of logs until the timeout

When follow is true, the server must use HTTP chunked-encoding to send a live stream of the logs.

Configure the log provider

The gateway will proxy log requests to the function provider, by default. To use an alternative log provider, simply set the logs_provider_url environment variable in your gateway server. The gateway will then proxy the logs requests to this URL.

Available providers

• faas-netes : the official Kubernetes function provider also provides logs by directly querying the Kubernetes cluster API
• faas-swarm : the official Swarm function provider also provides logs by directly querying the Swarm cluster API
• openfaas-loki : a community-developed provider, uses Grafana Loki to collection and query the function logs

Create a new provider

The github.com/openfaas/faas-provider/logs package provides a Go interface and utilities to simplify the creation of a new log provider. Once you hae implemented the Requester interface the other package utilities can be used to create the required http server. A very simple "static" logs example can be found in the faas-provider repo.