nodes.py

This file lets you specify or dynamically build a list of nodes in your environment.

All you have to do here is define a Python dictionary called nodes. It should look something like this:

nodes = {
    "node-1": {
        'hostname': "node-1.example.com",
    },
}

With BundleWrap, the DNS name and the internal identifier for a node ("node-1" in this case) are two separate things.

All fields for a node (including hostname) are optional. If you don't give one, BundleWrap will attempt to use the internal identifier to connect to a node:

nodes = {
    "node-1.example.com": {},
}

Dynamic node list

You are not confined to the static way of defining a node list as shown above. You can also assemble the nodes dictionary dynamically:

def get_my_nodes_from_ldap():
    [...]
    return ldap_nodes

nodes = get_my_nodes_from_ldap()

One file per node

Especially in larger installations, a single nodes.py can become inconvenient to work with. This example reads nodes from a nodes/ directory.

from glob import glob
from os.path import join

nodes = {}
for node in glob(join(repo_path, "nodes", "*.py")):
    with open(node, 'r') as f:
        exec(f.read())

Node files would then append nodes, like this:

# nodes/node-1.py
nodes['node-1'] = {
    'hostname': "node-1.example.com",
}

Node attribute reference

This section is a reference for all possible attributes you can define for a node:

nodes = {
    'node-1': {
        # THIS PART IS EXPLAINED HERE
    },
}

All attributes can also be set at the group level, unless noted otherwise.

Regular attributes

bundles

A list of bundle names to be assigned to this node. Bundles set at group level will be added.

dummy

Set this to True to prevent BundleWrap from creating items for and connecting to this node. This is useful for unmanaged nodes because you can still assign them bundles and metadata like regular nodes and access that from managed nodes (e.g. for monitoring).

hostname

A string used as a DNS name when connecting to this node. May also be an IP address.

Cannot be set at group level.

metadata

This can be a dictionary of arbitrary data (some type restrictions apply). You can access it from your templates as node.metadata. Use this to attach custom data (such as a list of IP addresses that should be configured on the target node) to the node. Note that you can also define metadata at the group level, but node metadata has higher priority.

You are restricted to using only the following types in metadata:

• dict
• list
• tuple
• set
• bool
• text / unicode
• bytes / str (only if decodable into text using UTF-8)
• int
• None
• bundlewrap.utils.Fault

os

Defaults to "linux".

A list of supported OSes can be obtained with bw debug -n ANY_NODE_NAME -c "print(node.OS_KNOWN)".

os_version

Set this to your OS version. Note that it must be a tuple of integers, e.g. if you're running Ubuntu 16.04 LTS, it should be (16, 4).

Tuples of integers can be used for easy comparison of versions: (12, 4) < (16, 4)

template_node

Copy all attributes and merge all metadata from this node. This is useful for temporary clones of single specific nodes, where you don't want to create a group to deduplicate all the node-level configuration.

Cannot be set at group level.

OS compatibility overrides

cmd_wrapper_outer

Used whenever a command needs to be run on a node. Defaults to "sudo sh -c {}". {} will be replaced by the quoted command to be run (after cmd_wrapper_inner has been applied).

You will need to override this if you're not using sudo to gain root privileges (e.g. doas) on the node.

cmd_wrapper_inner

Used whenever a command needs to be run on a node. Defaults to "export LANG=C; {}". {} will be replaced by the command to be run.

You will need to override this if the shell on your node sets environment variables differently.

use_shadow_passwords

This setting will affect how the user item item operates. If set to False, password hashes will be written directly to /etc/passwd and thus be accessible to any user on the system. If the OS of the node is set to "openbsd", this setting has no effect as master.shadow is always used.