Loggregator

Logging in the Clouds

Loggregator is the user application logging subsystem for Cloud Foundry.

Features

Loggregator allows users to:

1. Tail their application logs.
2. Dump a recent set of application logs (where recent is on the order of an hour).
3. Continually drain their application logs to 3rd party log archive and analysis services.

Usage

Proposed syntax:

cf logs [--space] [--app=APP_NAME|] [--tail]

$ cf logs --tail
Started GET "/" for 127.0.0.1 at 2013-04-05 13:14:58 -0700
Processing by Rails::WelcomeController#index as HTML
  Rendered /Users/tsaleh/.rbenv/versions/2.0.0-p0/lib/ruby/gems/2.0.0/gems/railties-4.0.0.beta1/lib/rails/templates/rails/welcome/index.html.erb (1.9ms)
Completed 200 OK in 12ms (Views: 11.3ms | ActiveRecord: 0.0ms)
Started GET "/assets/rails.png" for 127.0.0.1 at 2013-04-05 13:14:58 -0700
...
^C

Constraints

1. Loggregator collects STDOUT & STDERR from the customer's application. This may require configuration on the developer's side.
2. A Loggregator outage must not affect the running application.
3. Loggregator gathers and stores logs in a best-effort manner. While undesirable, losing the current buffer of application logs is acceptable.
4. The 3rd party drain API should mimic Heroku's in order to reduce integration effort for our partners. The Heroku drain API is simply remote syslog over TCP.

Architecture

Loggregator is composed of:

• Sources: Logging agents that run on the Cloud Foundry components. They forward logs to:
• Loggregator Server: Responsible for gathering logs from the sources, and storing in the temporary buffers.
• Loggregator Sink Server: Accepts connections from the cf CLI, allowing users to access their logs.
• Loggregator Drain Server: Implements the Heroku Drain API for 3rd party partners.

Source agents emit the logging data as protocol-buffers, and the data stays in that format throughout the system.

Development

The Cloud Foundry team uses GitHub and accepts contributions via pull request.

Follow these steps to make a contribution to any of our open source repositories:

1. Complete our CLA Agreement for individuals or corporations

2. Set your name and email

   git config --global user.name "Firstname Lastname" git config --global user.email "[email protected]"

3. Fork the repo

4. Make your changes on a topic branch, commit, and push to github and open a pull request.

Once your commits are approved by Travis CI and reviewed by the core team, they will be merged.

Checkout

git clone https://github.com/cloudfoundry/loggregator
cd loggregator
git submodule update --init

Running tests

bin/test

Debugging

Loggregator will dump information about the running goroutines to stdout if sent a USR1 signal.

goroutine 1 [running]:
runtime/pprof.writeGoroutineStacks(0xc2000bc3f0, 0xc200000008, 0xc200000001, 0xca0000c2001fcfc0)
	/home/travis/.gvm/gos/go1.1.1/src/pkg/runtime/pprof/pprof.go:511 +0x7a
runtime/pprof.writeGoroutine(0xc2000bc3f0, 0xc200000008, 0x2, 0xca74765c960d5c8f, 0x40bbf7, ...)
	/home/travis/.gvm/gos/go1.1.1/src/pkg/runtime/pprof/pprof.go:500 +0x3a
...

Development binary builds

Note: This is linux amd64 only

• dea_agent
• loggregator