confd

• IRC: #confd on Freenode
• Mailing list: Google Groups

confd is a lightweight configuration management tool focused on:

• keeping local configuration files up-to-date by polling etcd and processing template resources.
• reloading applications to pick up new config file changes

Getting Started

Installing confd

Download the latest binary from Github.

Building

You can build confd from source:

git clone https://github.com/kelseyhightower/confd.git
cd confd
go build

This will produce the confd binary in the current directory.

Usage

The following commands will process all the template resources found under /etc/confd/conf.d.

Poll the etcd cluster in 30 second intervals

The "/production" string will be prefixed to keys when querying etcd at http://127.0.0.1:4001.

confd -i 30 -p '/production' -n 'http://127.0.0.1:4001'

Single run without polling

Using default settings run one time and exit.

confd -onetime

Client authentication

Same as above but authenticate with client certificates.

confd -onetime -key /etc/confd/ssl/client.key -cert /etc/confd/ssl/client.crt

Configuration

The confd configuration file is written in TOML and loaded from /etc/confd/confd.toml by default.

Optional:

• confdir (string) - The path to confd configs. The default is /etc/confd.
• etcd_nodes (array of strings) - An array of etcd cluster nodes. The default is ["http://127.0.0.1:4001"].
• interval (int) - The number of seconds to wait between calls to etcd. The default is 600.
• prefix (string) - The prefix string to prefix to keys when making calls to etcd. The default is "/".
• client_cert (string) The cert file of the client.
• client_key (string) The key file of the client.

Example:

[confd]
confdir  = "/etc/confd"
interval = 600
prefix   = "/"
etcd_nodes = [
  "http://127.0.0.1:4001",
]
client_cert = "/etc/confd/ssl/client.crt"
client_key  = "/etc/confd/ssl/client.key"

Template Resources

Template resources are written in TOML and define a single template resource. Template resources are stored under the confdir/conf.d directory.

Required:

• dest (string) - output file where the template should be rendered.
• keys (array of strings) - An array of etcd keys. Keys will be looked up with the configured prefix.
• src (string) - relative path of a the configuration template.

Optional:

• group (string) - name of the group that should own the file.
• mode (string) - mode the file should be in.
• owner (string) - name of the user that should own the file.
• reload_cmd (string) - command to reload config.
• check_cmd (string) - command to check config. Use {{ .src }} to reference the rendered source template.

Example:

[template]
src   = "nginx.conf.tmpl"
dest  = "/etc/nginx/nginx.conf"
owner = "root"
group = "root"
mode  = "0644"
keys = [
  "/nginx",
]
check_cmd  = "/usr/sbin/nginx -t -c {{ .src }}"
reload_cmd = "/usr/sbin/service nginx restart"

Templates

Templates define a single application configration template. Templates are stored under the confdir/templates directory.

Templates are written in Go's text/template.

Etcd keys are treated as paths and automatically transformed into keys for retrieval in templates. Underscores are used in place of forward slashes. Values retrived from Etcd are never modified.
For example /foo/bar becomes foo_bar.

foo_bar is accessed as {{ .foo_bar }}

Example:

$ etcdctl set /nginx/domain 'example.com'
$ etcdctl set /nginx/root '/var/www/example_dotcom'
$ etcdctl set /nginx/worker_processes '2'

$ cat /etc/confd/templates/nginx.conf.tmpl:

worker_processes {{ .nginx_worker_processes }};

server {
    listen 80;
    server_name www.{{ .nginx_domain }};
    access_log /var/log/nginx/{{ .nginx_domain }}.access.log;
    error_log /var/log/nginx/{{ .nginx_domain }}.log;

    location / {
        root   {{ .nginx_root }};
        index  index.html index.htm;
    }
}

Will produce /etc/nginx/nginx.conf:

worker_processes 2;

server {
    listen 80;
    server_name www.example.com;
    access_log /var/log/nginx/example.com.access.log;
    error_log /var/log/nginx/example.com.error.log;

    location / {
        root   /var/www/example_dotcom;
        index  index.html index.htm;
    }
}

Go's text/template package is very powerful. For more details on it's capabilities see its documentation.

Extras

Configuration Management

• confd-cookbook