docker-gen

docker-gen is a file generator that renders templates using docker container meta-data.

docker-gen can be used to generate various kinds of files for:

• Centralized logging - fluentd, logstash or other centralized logging tools that tail the containers JSON log file or files within the container.
• Log Rotation - logrotate files to rotate container JSON log files
• Reverse Proxy Configs - nginx, haproxy, etc. reverse proxy configs to route requests from the host to containers
• Service Discovery - Scripts (python, bash, etc..) to register containers within etcd, hipache, etc..

===

Installation

Host Install

Linux binaries for release 0.3.3

• amd64
• i386

Download the version you need, untar, and install to your PATH.

$ wget https://github.com/jwilder/docker-gen/releases/download/0.3.3/docker-gen-linux-amd64-0.3.3.tar.gz
$ tar xvzf docker-gen-linux-amd64-0.3.3.tar.gz
$ ./docker-gen

Container Install

See jwilder/nginx-proxy trusted build as an example of running docker-gen within a container.

Usage

$ docker-gen
Usage: docker-gen [options] <template> [<dest>]

[-config file] [-watch=false] [-notify="restart xyz"] [-interval=0] [-endpoint tcp|unix://..]

Options:

  -config="": Use the specified config file instead of command-line options.  Multiple templates can be defined and 
              they will be executed in the order that they appear in the config file.
  -endpoint="": docker api endpoint [tcp|unix://..]. This can also be set w/ a `DOCKER_HOST` environment.
  -interval=0:run notify command interval (s). Useful for service registration use cases.
  -notify="": run command after template is regenerated ["restart xyz"]. Useful for restarting nginx,
              reloading haproxy, etc..
  -only-exposed=false: only include containers with exposed ports
  -only-published=false: only include containers with published ports (implies -only-exposed)
  -version=false: show version
  -watch=false: run continuously and monitors docker container events.  When containers are started
                or stopped, the template is regenerated.

If no <dest> file is specified, the output is sent to stdout. Mainly useful for debugging.

Examples

NGINX Reverse Proxy Config

Containerized

jwilder/nginx-proxy trusted build.

Start nginx-proxy:

$ docker run -d -p 80:80 -v /var/run/docker.sock:/tmp/docker.sock -t jwilder/nginx-proxy

Then start containers with a VIRTUAL_HOST env variable:

$ docker run -e VIRTUAL_HOST=foo.bar.com -t ...

Host Install

$ docker-gen -only-exposed -watch -notify "/etc/init.d/nginx reload" templates/nginx.tmpl /etc/nginx/sites-enabled/default

Automated Nginx Reverse Proxy for Docker

Fluentd Log Management

$ docker-gen -watch -notify "restart fluentd" templates/fluentd.tmpl /etc/fluent/fluent.conf

Docker Log Management With Fluentd

Register Containers in Etcd

$ docker-gen -notify "/bin/bash /tmp/etcd.sh" -interval 10 templates/etcd.tmpl /tmp/etcd.sh

Development

This project uses godep for managing 3rd party dependencies. You'll need to install godep into your workspace before hacking on docker-gen.

$ git clone <your fork>
$ godep restore
$ make

TODO

• Add event status for handling start and stop events differently
• Add a way to filter out containers in templates