Docker Label Inspector is a tool to help ensure you're providing your Docker images with the metadata they will need out in the wilds of the internet.

It provides two useful tools; a label linter and a label validator.

Usage

The package includes a single executable, called dli. You can pass --help to individual commands for additional instructions and options.

$ dli
Usage: dli [OPTIONS] COMMAND [ARGS]...

  Utilities for ensuring LABELS in Dockerfiles are well maintained

Options:
  --help  Show this message and exit.

Commands:
  lint      Check for common issues with Dockerfile...
  validate  Validate Dockerfile LABELS based on a JSON...

Linter

The linter checks your labels against the official LABEL guidelines. By default dli will check the file called Dockerfile in the present working directory. You can pass a path via the --dockerfile option.

$ dli lint
========> Check all labels have namespaces
   [WARN] Label 'vendor' should use a namespace based on reverse DNS notation
========> Check labels don't use reserved namespaces
========> Check labels only use valid characters
========> Check labels start and end with alpanumeric characters
========> Check labels for double dots and dashes

dli lint will return a non-zero exit code if it finds any errors. This should make it useful for integrating into pipelines.

Validator

The validator validates the labels against a provided JSON Schema. The idea being you can use a custom schema for your organisation or, eventually, community provided schemas.

dli validate
========> Check labels based on schema in 'schema.json'

You can see a working example in the example directory. This includes a sample schema and Dockerfile. You can see sample output from an invalid Dockerfile below, in this case missing a required parameter.

$ dli validate
========> Check labels based on schema in 'schema.json'
  [ERROR] u'com.example.is-beta' is a required property

Failed validating u'required' in schema:
    {u'properties': {u'com.example.is-beta': {u'type': u'string'},
                     u'com.example.release-date': {u'type': u'string'},
                     u'com.example.version': {u'description':
u'Version',
                                              u'minimum': 0,
                                              u'type': u'integer'}},
     u'required': [u'com.example.is-beta', u'com.example.version'],
     u'title': u'Dockerfile schema',
     u'type': u'object'}

On instance:
    {u'com.example.release-date': u'2015-02-12',
     u'com.example.version': 1,
     u'vendor': u'ACME Incorporated'}

Installation

For the moment you can install from this repository using pip.

git clone git@github.com:garethr/docker-label-inspector.git
cd docker-label-inspector
pip install .