latest 0.7.3 Build Status License MIT

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

It 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..

===

There are three common ways to run docker-gen:

• on the host
• bundled in a container with another application
• separate standalone containers

Linux/OSX binaries for release 0.7.3

• amd64
• i386
• alpine-linux

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

$ wget https://github.com/jwilder/docker-gen/releases/download/0.7.3/docker-gen-linux-amd64-0.7.3.tar.gz
$ tar xvzf docker-gen-linux-amd64-0.7.3.tar.gz
$ ./docker-gen

Docker-gen can be bundled inside of a container along-side applications.

jwilder/nginx-proxy trusted build is an example of running docker-gen within a container along-side nginx. jwilder/docker-register is an example of running docker-gen within a container to do service registration with etcd.

It can also be run as two separate containers using the jwilder/docker-gen image, together with virtually any other image.

This is how you could run the official nginx image and have docker-gen generate a reverse proxy config in the same way that nginx-proxy works. You may want to do this to prevent having the docker socket bound to a publicly exposed container service.

Start nginx with a shared volume:

$ docker run -d -p 80:80 --name nginx -v /tmp/nginx:/etc/nginx/conf.d -t nginx

Fetch the template and start the docker-gen container with the shared volume:

$ mkdir -p /tmp/templates && cd /tmp/templates
$ curl -o nginx.tmpl https://raw.githubusercontent.com/jwilder/docker-gen/master/templates/nginx.tmpl
$ docker run -d --name nginx-gen --volumes-from nginx \
 -v /var/run/docker.sock:/tmp/docker.sock:ro \
 -v /tmp/templates:/etc/docker-gen/templates \
 -t jwilder/docker-gen -notify-sighup nginx -watch -only-exposed /etc/docker-gen/templates/nginx.tmpl /etc/nginx/conf.d/default.conf

===

$ docker-gen
Usage: docker-gen [options] template [dest]
Generate files from docker container meta-data
Options:
 -config value
 config files with template directives. Config files will be merged if this option is specified multiple times. (default [])
 -endpoint string
 docker api endpoint (tcp|unix://..). Default unix:///var/run/docker.sock
 -interval int
 notify command interval (secs)
 -keep-blank-lines
 keep blank lines in the output file
 -notify restart xyz
 run command after template is regenerated (e.g restart xyz)
 -notify-output
 log the output(stdout/stderr) of notify command
 -notify-sighup container-ID
 send HUP signal to container. Equivalent to 'docker kill -s HUP container-ID'
 -only-exposed
 only include containers with exposed ports
 -only-published
 only include containers with published ports (implies -only-exposed)
 -include-stopped
 include stopped containers
 -tlscacert string
 path to TLS CA certificate file (default "/Users/jason/.docker/machine/machines/default/ca.pem")
 -tlscert string
 path to TLS client certificate file (default "/Users/jason/.docker/machine/machines/default/cert.pem")
 -tlskey string
 path to TLS client key file (default "/Users/jason/.docker/machine/machines/default/key.pem")
 -tlsverify
 verify docker daemon's TLS certicate (default true)
 -version
 show version
 -watch
 watch for container changes
 -wait
 minimum (and/or maximum) duration to wait after each container change before triggering
Arguments:
 template - path to a template to generate
 dest - path to a write the template. If not specfied, STDOUT is used
Environment Variables:
 DOCKER_HOST - default value for -endpoint
 DOCKER_CERT_PATH - directory path containing key.pem, cert.pm and ca.pem
 DOCKER_TLS_VERIFY - enable client TLS verification]

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

Using the -config flag from above you can tell docker-gen to 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.

An example configuration file, docker-gen.cfg can be found in the examples folder.

[[config]]
Starts a configuration section
dest = "path/to/a/file"
path to a write the template. If not specfied, STDOUT is used
notifycmd = "/etc/init.d/foo reload"
run command after template is regenerated (e.g restart xyz)
onlyexposed = true
only include containers with exposed ports
template = "/path/to/a/template/file.tmpl"
path to a template to generate
watch = true
watch for container changes
wait = "500ms:2s"
debounce changes with a min:max duration. Only applicable if watch = true
[config.NotifyContainers]
Starts a notify container section
containername = 1
container name followed by the signal to send
container_id = 1
or the container id can be used followed by the signal to send

Putting it all together here is an example configuration file.

[[config]]
template = "/etc/nginx/nginx.conf.tmpl"
dest = "/etc/nginx/sites-available/default"
onlyexposed = true
notifycmd = "/etc/init.d/nginx reload"
[[config]]
template = "/etc/logrotate.conf.tmpl"
dest = "/etc/logrotate.d/docker"
watch = true
[[config]]
template = "/etc/docker-gen/templates/nginx.tmpl"
dest = "/etc/nginx/conf.d/default.conf"
watch = true
wait = "500ms:2s"
[config.NotifyContainers]
nginx = 1 # 1 is a signal number to be sent; here SIGHUP
e75a60548dc9 = 1 # a key can be either container name (nginx) or ID

===

The templates used by docker-gen are written using the Go text/template language. In addition to the built-in functions supplied by Go, docker-gen provides a number of additional functions to make it simpler (or possible) to generate your desired output.

Within the templates, the object emitted by docker-gen will be a structure consisting of following Go structs:

type RuntimeContainer struct {
 ID string
 Addresses []Address
 Networks []Network
 Gateway string
 Name string
 Hostname string
 Image DockerImage
 Env map[string]string
 Volumes map[string]Volume
 Node SwarmNode
 Labels map[string]string
 IP string
 IP6LinkLocal string
 IP6Global string
 Mounts []Mount
 State State
}
type Address struct {
 IP string
 IP6LinkLocal string
 IP6Global string
 Port string
 HostPort string
 Proto string
 HostIP string
}
type Network struct {
 IP string
 Name string
 Gateway string
 EndpointID string
 IPv6Gateway string
 GlobalIPv6Address string
 MacAddress string
 GlobalIPv6PrefixLen int
 IPPrefixLen int
}
type DockerImage struct {
 Registry string
 Repository string
 Tag string
}
type Mount struct {
 Name string
 Source string
 Destination string
 Driver string
 Mode string
 RW bool
}
type Volume struct {
 Path string
 HostPath string
 ReadWrite bool
}
type SwarmNode struct {
 ID string
 Name string
 Address Address
}
type State struct {
 Running bool
}
// Accessible from the root in templates as .Docker
type Docker struct {
 Name string
 NumContainers int
 NumImages int
 Version string
 ApiVersion string
 GoVersion string
 OperatingSystem string
 Architecture string
 CurrentContainerID string
}
// Host environment variables accessible from root in templates as .Env

For example, this is a JSON version of an emitted RuntimeContainer struct:

{
 "ID":"71e9768075836eb38557adcfc71a207386a0c597dbeda240cf905df79b18cebf",
 "Addresses":[
 {
 "IP":"172.17.0.4",
 "Port":"22",
 "Proto":"tcp",
 "HostIP":"192.168.10.24",
 "HostPort":"2222"
 }
 ],
 "Gateway":"172.17.42.1",
 "Node": {
 "ID":"I2VY:P7PF:TZD5:PGWB:QTI7:QDSP:C5UD:DYKR:XKKK:TRG2:M2BL:DFUN",
 "Name":"docker-test",
 "Address": {
 "IP":"192.168.10.24"
 }
 },
 "Labels": {
 "operatingsystem":"Ubuntu 14.04.2 LTS",
 "storagedriver":"devicemapper",
 "anything_foo":"something_bar"
 },
 "IP":"172.17.0.4",
 "Name":"docker_register",
 "Hostname":"71e976807583",
 "Image":{
 "Registry":"jwilder",
 "Repository":"docker-register"
 },
 "Env":{
 "ETCD_HOST":"172.17.42.1:4001",
 "PATH":"/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin",
 "DOCKER_HOST":"unix:///var/run/docker.sock",
 "HOST_IP":"172.17.42.1"
 },
 "Volumes":{
 "/mnt":{
 "Path":"/mnt",
 "HostPath":"/Users/joebob/tmp",
 "ReadWrite":true
 }
 }
}

• closest $array $value: Returns the longest matching substring in $array that matches $value
• coalesce ...: Returns the first non-nil argument.
• contains $map $key: Returns true if $map contains $key. Takes maps from string to string.
• dict $key $value ...: Creates a map from a list of pairs. Each $key value must be a string, but the $value can be any type (or nil). Useful for passing more than one value as a pipeline context to subtemplates.
• dir $path: Returns an array of filenames in the specified $path.
• exists $path: Returns true if $path refers to an existing file or directory. Takes a string.
• first $array: Returns the first value of an array or nil if the arry is nil or empty.
• groupBy $containers $fieldPath: Groups an array of RuntimeContainer instances based on the values of a field path expression $fieldPath. A field path expression is a dot-delimited list of map keys or struct member names specifying the path from container to a nested value, which must be a string. Returns a map from the value of the field path expression to an array of containers having that value. Containers that do not have a value for the field path in question are omitted.
• groupByKeys $containers $fieldPath: Returns the same as groupBy but only returns the keys of the map.
• groupByMulti $containers $fieldPath $sep: Like groupBy, but the string value specified by $fieldPath is first split by $sep into a list of strings. A container whose $fieldPath value contains a list of strings will show up in the map output under each of those strings.
• groupByLabel $containers $label: Returns the same as groupBy but grouping by the given label's value.
• hasPrefix $prefix $string: Returns whether $prefix is a prefix of $string.
• hasSuffix $suffix $string: Returns whether $suffix is a suffix of $string.
• intersect $slice1 $slice2: Returns the strings that exist in both string slices.
• json $value: Returns the JSON representation of $value as a string.
• keys $map: Returns the keys from $map. If $map is nil, a nil is returned. If $map is not a map, an error will be thrown.
• last $array: Returns the last value of an array.
• parseBool $string: parseBool returns the boolean value represented by the string. It accepts 1, t, T, TRUE, true, True, 0, f, F, FALSE, false, False. Any other value returns an error. Alias for strconv.ParseBool
• replace $string $old $new $count: Replaces up to $count occurences of $old with $new in $string. Alias for strings.Replace
• sha1 $string: Returns the hexadecimal representation of the SHA1 hash of $string.
• split $string $sep: Splits $string into a slice of substrings delimited by $sep. Alias for strings.Split
• splitN $string $sep $count: Splits $string into a slice of substrings delimited by $sep, with number of substrings returned determined by $count. Alias for strings.SplitN
• trimPrefix $prefix $string: If $prefix is a prefix of $string, return $string with $prefix trimmed from the beginning. Otherwise, return $string unchanged.
• trimSuffix $suffix $string: If $suffix is a suffix of $string, return $string with $suffix trimmed from the end. Otherwise, return $string unchanged.
• trim $string: Removes whitespace from both sides of $string.
• when $condition $trueValue $falseValue: Returns the $trueValue when the $condition is true and the $falseValue otherwise
• where $items $fieldPath $value: Filters an array or slice based on the values of a field path expression $fieldPath. A field path expression is a dot-delimited list of map keys or struct member names specifying the path from container to a nested value. Returns an array of items having that value.
• whereNot $items $fieldPath $value: Filters an array or slice based on the values of a field path expression $fieldPath. A field path expression is a dot-delimited list of map keys or struct member names specifying the path from container to a nested value. Returns an array of items not having that value.
• whereExist $items $fieldPath: Like where, but returns only items where $fieldPath exists (is not nil).
• whereNotExist $items $fieldPath: Like where, but returns only items where $fieldPath does not exist (is nil).
• whereAny $items $fieldPath $sep $values: Like where, but the string value specified by $fieldPath is first split by $sep into a list of strings. The comparison value is a string slice with possible matches. Returns items which OR intersect these values.
• whereAll $items $fieldPath $sep $values: Like whereAny, except all $values must exist in the $fieldPath.
• whereLabelExists $containers $label: Filters a slice of containers based on the existence of the label $label.
• whereLabelDoesNotExist $containers $label: Filters a slice of containers based on the non-existence of the label $label.
• whereLabelValueMatches $containers $label $pattern: Filters a slice of containers based on the existence of the label $label with values matching the regular expression $pattern.

===

• Automated Nginx Reverse Proxy for Docker
• Docker Log Management With Fluentd
• Docker Service Discovery Using Etcd and Haproxy

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 ...

If you wanted to run docker-gen directly on the host, you could do it with:

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

This template generate a fluentd.conf file used by fluentd. It would then ship log files off the host.

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

This template is an example of generating a script that is then executed. This template generates a python script that is then executed which register containers in Etcd using its HTTP API.

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

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

$ git clone <your fork>
$ cd <your fork>
$ make get-deps
$ make

• Add event status for handling start and stop events differently

MIT