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CF syslog drain release is a Bosh release that works in conjunction with Loggregator to bind applications to syslog readers. It can be independently scaled to support large numbers of User Provided syslog drains.

The Loggregator Design Notes present an overview of Loggregator components and architecture.

Supported Features and Release

This release is tested to work with cf-deployment only and is currently included in cf-deployment by default. Syslog drains in cf-release are still handled by Dopplers.

Drain Types (Experimental)

Syslog drains now support an experimental feature that you can opt into by downloading the cf-drain-cli plugin. and setting a feature flag. This plugin allows you to specify the following "drain types".

  • logs - this is the default behavior and will deliver all application logs
  • metrics - this will deliver any metric for an application every 15 seconds
  • all - this will deliver both metrics and logs for an application

This sample drain application can be used to demo this functionality with Datadog. Note This requires setting the property scalablesyslog.adapter.metrics_to_syslog_enabled to true.

Log Ordering

Ensuring log ordering in drains can be an important consideration for both operators and developers. Diego uses a nanosecond based timestamp that can be ingested properly by Splunk with the instructions linked.

ELK can ingest the nanosecond timestamps but only supports millisecond precision so timestamps will be truncated. See ELK's date type and the relevant issue.

Additionally a workaround exists specifically for Java stack traces and ELK.

Configuring CF Syslog Drain Components

The cf syslog drain release contains three components.


This component handles communication with the Cloud Controller to receive new bindings. It uses a deterministic algorithm to schedule drains and should be scaled to a single instance per zone.

Reverse Log Proxy (RLP)

This component scales in conjunction with your overall log volume. We recommend no less than 2 instances for High Availability and 1/2 your number of Traffic Controllers. Note that RLP is a component of the Loggregator release.

Syslog Adapter

This component manages the connections to external log storage systems and enforces a hard limit of 500 streams. Since each syslog-drain creates 2 streams to provide a highly available stream distribution we recommend the following metric and formula to determine number of adapters and allow for headroom for new bindings.

Num of Adapters = (cf-syslog-drain.scheduler.drains / 250) + 2

Operator Metrics

The following new metrics are emitted:

  • loggregator.rlp.ingress - ingress into reverse log proxy
  • loggregator.rlp.egress - egress out of reverse log proxy
  • cf-syslog-drain.adapter.ingress - ingress into adapters (these are tagged by index and drain protocol)
  • cf-syslog-drain.adapter.engress - engress out of adapters (these are tagged by index and drain protocol)
  • cf-syslog-drain.adapter.dropped - dropped messages on adapters (these are tagged by index and drain protocol)
  • cf-syslog-drain.scheduler.drains- total number of syslog drain bindings

Other Configurations

Note: The default behavior for syslog-drain cert verification has changed with this release. It now will validate certificates by default. To override this setting you can set the property: scalablesyslog.adapter.syslog_skip_cert_verify.

Deploying CF Syslog Drain Release (standalone)

The release is built to be deployed independently. It can also be used as a composite release within cf-deployment. The following steps are for deploying it independently.

The provided manifest is setup to use the common cloud config.

To deploy to bosh-lite run the following commands:

bosh -e lite upload-release
bosh -e lite update-cloud-config $HOME/workspace/bosh-deployment/warden/cloud-config.yml
cd $HOME/workspace/cf-syslog-drain-release
bosh create-release --force
bosh -e lite upload-release --rebase
bosh -e lite -d cf-syslog-drain deploy manifests/cf-syslog-drain.yml -o manifests/fake-ops.yml --vars-store=/tmp/bosh-lite-ss.yml

Generating Certificates

To deploy the cf syslog drain release, you will need three sets of certificates for the following connections:

  • The scheduler to Cloud Controller
  • The scheduler to the adapters
  • The adapters to the reverse log proxies

To generate these certs, you will need the CA used within Loggregator, as well as the CA used to sign the Cloud Controller certificate. This is typically the diego BBS CA.

Assuming you have these two CAs, run the following commands:

./scripts/generate-certs bbs-ca.crt bbs-ca.key loggregator-ca.crt loggregator-ca.key