Writing file templates
BundleWrap can use Mako or Jinja2 for file templating. This enables you to dynamically contruct your config files. Templates reside in the files
subdirectory of a bundle and are bound to a file item using the source
attribute. This page explains how to get started with Mako.
The most basic example would be:
Hello, this is ${node.name}!
After template rendering, it would look like this::
Hello, this is myexamplenodename!
As you can see, ${...}
can be used to insert the value of a context variable into the rendered file. By default, you have access to two variables in every template: node
and repo
. They are bundlewrap.node.Node
and bundlewrap.repo.Repository
objects, respectively. You can learn more about the attributes and methods of these objects in the API docs, but here are a few examples:
Examples
inserts the DNS hostname of the current node
${node.hostname}
a list of all nodes in your repo
% for node in repo.nodes:
${node.name}
% endfor
make exceptions for certain nodes
% if node.name == "node1":
option = foo
% elif node.name in ("node2", "node3"):
option = bar
% else:
option = baz
% endif
check for group membership
% if node.in_group("sparkle"):
enable_sparkles = 1
% endif
check for membership in any of several groups
% if node.in_any_group(("sparkle", "shiny")):
enable_fancy = 1
% endif
check for bundle
% if node.has_bundle("sparkle"):
enable_sparkles = 1
% endif
check for any of several bundles
% if node.has_any_bundle(("sparkle", "shiny")):
enable_fancy = 1
% endif
list all nodes in a group
% for gnode in repo.get_group("mygroup").nodes:
${gnode.name}
% endfor
Working with node metadata
Quite often you will attach custom metadata to your nodes in nodes.py
, e.g.:
nodes = {
"node1": {
"metadata": {
"interfaces": {
"eth0": "10.1.1.47",
"eth1": "10.1.2.47",
},
},
},
}
You can easily access this information in templates:
% for interface, ip in sorted(node.metadata["interfaces"].items()):
interface ${interface}
ip = ${ip}
% endfor
This template will render to:
interface eth0
ip = 10.1.1.47
interface eth1
ip = 10.1.2.47