Read all YAML files in a directory and merge them
Latest commit 31b1adc Jan 18, 2017 @mriehl mriehl better fix for #9


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Merge YAML data from a directory, a list of files or a file glob. With a directory, the YAML files (*.yaml) are sorted alphabetically. The YAML files are expected to contain a complex key-value structure and merged with the following rules:

  • lists get appended
  • hashes get merged by key
  • scalars (numbers, strings) are overwritten
  • everything else will fail

The purpose is to allow several YAML files instead of a single YAML file. We use it to help our software read configuration data from an arbitrary amount of YAML files instead of a single YAML file.

Read the unit test to see some examples.

Building and Installation

Using pip

yamlreader is available with pip:

pip install yamlreader

Manual build and installation

If you want to make changes or use e.g. fpm for packaging this, you need to prepare the development environment to make further steps.

Prepare the source
git clone
cd yamlreader
virtualenv venv
source venv/bin/activate
pip install pybuilder
pyb install_dependencies
Running tests
pyb verify
Generating a
cd target/dist/yamlreader-<VERSION>
./ <whatever you want>


The package installs a command line script yamlreader that can be used to read one or many YAML files and dump the merge result as a YAML document.

Use it in your software

Wherever you had been using the safe_load function of PyYAML to read a single YAML file you can use the yamlreader.yaml_load function as a replacement to read all *.yaml files in a directory:

from yamlreader import yaml_load

defaultconfig = {
        "loglevel" : "error",
        "some" : "value"

config = yaml_load("/etc/myapp", defaultconfig)


def yaml_load(source,defaultdata=None):
    """merge YAML data from files found in source

    Always returns a dict. The YAML files are expected to contain some kind of
    key:value structures, possibly deeply nested. When merging, lists are
    appended and dict keys are replaced. The YAML files are read with the
    yaml.safe_load function.

    source can be a file, a dir, a list/tuple of files or a string containing
    a glob expression (with ?*[]).

    For a dir all *.yaml files will be read in alphabetical order.

    defaultdata can be used to initialize the data.