trafficcontroller

README

Traffic Controller

Traffic Controller is a Cloud Foundry component that handles client requests for logs and metrics. It gathers and collates messages from all Doppler servers, and provides an external API and message translation.

Traffic Controller handles inbound HTTP and WebSocket requests for log and metric data. It does this by proxying the request to all Dopplers (regardless of AZ). Since an application can be deployed to multiple AZs, its logs can potentially end up on Dopplers in multiple AZs. This is why the traffic controller will attempt to connect to Dopplers in each AZ and will collate the data into a single stream for the web socket client.

The Traffic Controller itself is stateless; an incoming request can be handled by any instance in any AZ. As such, Traffic Controller is horizontally scalable.

Traffic Controllers also expose a firehose web socket endpoint. Connecting to this endpoint establishes connections to all Dopplers, and streams logs and metrics for all applications and CF components. There are firehose examples within the NOAA library.

Architecture Within Loggregator

Logging data passes through the system as protocol-buffers, using Dropsonde.

Usage

trafficcontoller [--logFile <path to log file>] [--config <path to config file>] \
    [--cpuprofile <path to desired CPU profile>] \
    [--memprofile <path to desired memory profile>]

Flag	Required	Description
--logFile	No, default: STDOUT	The agent log file.
--config	No, default: config/loggregator_trafficcontroller.json	Location of the Traffic Controller configuration JSON file.
--cpuprofile	No, default: no CPU profiling	Write CPU profile to a file.
--memprofile	No, default: no memory profiling	Write memory profile to a file.
--disableAccessControl	No, default: false	All clients' access to app logs

Editing Manifest Templates

The up-to-date Traffic-Controller configuration can be found in the Traffic-Controller spec file. You can see a list of available configurable properties, their defaults and descriptions in that file.

Endpoints

Traffic Controller exposes a few endpoints from which clients like NOAA use to obtain logs and metrics.

Endpoint	Description
/apps/APP_ID/stream	Opens a websocket connection that streams metrics and logs for the specified app ID. The types of available metrics are specified by this function. Any metric or log that has an app ID will be sent.
/apps/APP_ID/recentlogs	Returns an HTTP response with the most recent logs for the specified application. The number of logs returned can be configured via the Doppler property doppler.maxRetainedLogMessages.
/apps/APP_ID/containermetrics	Returns an HTTP response with the latest container metrics for the specified application.
/firehose/SUBSCRIPTION_ID	Opens a websocket connection that streams the firehose. Connections with the same subscription id will get an equal portion of the firehose data.
/set-cookie	Sets a cookie with name and value obtained from FormValues CookieName and CookieValue. It also sets the headers Access-Control-Allow-Credentials and Access-Control-Allow-Origin.