Table of Contents

Augments

Table of Contents

An augments file can be used to define variables and classes to the execution of all CFEngine components before any parsing or evaluation happen. It's a JSON data file, so you should view and edit it with a JSON-aware editor if possible.This is a convenient way to override defaults defined in the Masterfiles Policy Framework without modifying the shipped policy itself.

The file def.json is found like the policy file to be run:

with no arguments, it's in $(sys.inputdir)/def.json because $(sys.inputdir)/promises.cf is used
with -f /dirname/myfile.cf, it's in /dirname/def.json
with -f myfile.cf, it's in ./def.json

Values will be expanded, so you can use the variables from Special Variables.

Currently the augments file can contain three keys:

inputs: any filenames you put here will appear in the def.augments_inputs variable. The standard set of masterfiles refers to this variable and will autoload those files.
vars: any variables you put here will be put in the def scope. Thus:
```
"vars":
{
"phone": "22-333-4444",
"myplatform": "$(sys.os)",
}
```
results in the variable def.phone with value 22-333-4444 being defined, and def.myplatform with the value of your current OS. Again, note that this happens before policy is parsed or evaluated.

You can see the list of variables thus defined in the output of cf-promises --show-vars (see Components and Common Control). They will be tagged with the tag source=augments_file. For instance, the above two variables (assuming you placed the data in $(sys.inputdir)/def.json) result in
```
cf-promises --show-vars
...
default:def.myplatform                   linux                                                        source=augments_file
default:def.phone                        22-333-4444                                                  source=augments_file
```
classes: any class names you put here will be evaluated and installed as hard classes if they match as a class name or a regular expression. Thus:
```
"classes":
{
"my_always": "any",
"my_other_apache": [ "server[34]", "debian.*" ],
}
```
results in my_always being always defined. my_other_apache will be defined if the classes server3 or server4 are defined, or if any class starting with debian is defined. You can use any hard classes listed in Hard and Soft Classes with the exception of am_policy_hub and policy_server.

You can see the list of classes thus defined through def.json in the output of cf-promises --show-classes (see Components and Common Control). They will be tagged with the tags source=augments_file,hardclass. For instance, the above two classes result in:
```
% cf-promises --show-classes
...
my_always                                                    source=augments_file,hardclass
my_other_apache                                              source=augments_file,hardclass
```

History: Introduced into the Masterfiles Policy Framework with CFEngine 3.7.0, the file def.json in the root of the policy directory was processed by policy. In CFEngine 3.8.1 def.json parsing was moved from a policy level feature into the core agent to address usability issues. It was also possible to use inputs to autoload inputs without referencing the def.augments_inputs variable. This would happen before all evaluation stages. However, this functionality turned out to be problematic and was removed in later versions. Pre-parsing of def.cf was introduced to the 3.7.x series in 3.7.3. In 3.7.3, 3.8.2 and later def.json is looked for next to the policy entry file.