MILV

Overview

MILV stands for "Markdown internal and external links validation." It is a tool that parses, checks, and validates internal and external URL links in Markdown files. You can use it either for verifying pull requests or as a standalone library.

Prerequisites

To use MILV, you must have GoLang in version 1.15 or higher installed.

Installation

Build a binary

Run the following commands to get the source code, resolve external dependencies, and build the project. The output binary named milv will be created in the project directory.

git clone https://github.com/kyma-incubator/milv.git
cd milv
make build

Build a Docker image

Build a Docker image out of MILV to use it in a continuous integration pipeline.

make build-image

You can use the Docker image in the same way as the MILV binary. To do that, mount a directory that MILV should validate.

cd ..
docker run -v $PWD:/milv milv -base-path milv

Usage

Definitions

MILV's logic is based on this basic distinction:

• Internal link is the link to the local resource, header, or any other file.
• External link is the link to the HTTP resource.

Command line parameters

You can use the following parameters when using the MILV binary:

Name	Description	Default Value
-base-path	Root directory of the repository	""
-backoff	Backoff timeout	"1s"
-config-file	Configuration file for the bot. See the Configuration file for more details.	milv.config.yaml
-external-links-to-ignore	Comma-separated external links which MILV must not check	[]
-internal-links-to-ignore	Comma-separated internal links which MILV must not check	[]
-files-to-ignore	Comma-separated files which MILV must not check	[]
-allow-redirect	Redirects should be allowed	false
-request-repeats	Number of repeated request	1
-allow-code-blocks	Validating links in code blocks should be allowed	false
-timeout	Connection timeout (in seconds)	30
-ignore-external	External links that MILV must ignore	false
-ignore-internal	Internal links that MILV must ignore	false
-v	Verbose logging	false
-help or -h	Available parameters	n/a

Files to be checked are given as free parameters.

See these examples:

• Use this command to check all links except for the vendor directory in the project and external links containing the github.com address.

  milv -files-to-ignore="vendor" -external-links-to-ignore="github.com"

• Use this command to check all links in the ./README.md and ./foo/bar.md files:

  milv ./README.md ./foo/bar.md

Configuration file

MILV relies on the milv.config.yaml configuration file in which you define rules and exceptions for MILV, stating which files and types of links it should validate or ignore. See the Configuration file document for a sample milv.config.yaml and a list of parameters you can use to configure it.

Typical errors

The table describes types of errors MILV can return while checking the links and sample solutions to these issues:

Error	Solution example
404 Not Found	This page doesn't exist. Change the external link to the correct one.
Error with link formatting	Correct the link. If the link contains variables or is used as an example, add it to the external-links-to-ignore or internal-links-to-ignore list.
The specified file doesn't exist	Change the relative path to the file to the correct one. Alternatively, use an absolute path.
The specified header doesn't exist in this file	Change the anchor link in the MD file to the correct one. MILV sometimes gives a hint (Did you mean {similar header}?) and points to an existing header in the file that is very similar to the one provided.
The specified anchor doesn't exist or The specified anchor doesn't exist on the website	Check which anchors are on the external website and correct the specified anchor or remove the redirection to the given anchor. MILV sometimes gives a hint (Did you mean {similar anchor}?) and points to an existing header in the file that is very similar to the one provided.
Get {external link}: net/http: request canceled (Client.Timeout exceeded while awaiting headers)	Increase net timeout for all files, a specific file, or a specific link. Alternatively, increase the the value for request-repeats. See the Configuration file for more details.
Get {external link}: EOF	Follow the already mentioned steps. You can also change the link to another one as it is possible that the website doesn't exist.
Other types of errors, such as errors that contain the no such host or timeout words	It means that the website doesn't exist or you don't have access to it. You can change the link to another one, correct, or remove it. Alternatively, add the link to the external-links-to-ignore or internal-links-to-ignore list.

It is considered a good practice to add external local links (in the local network) to the global ignore list of external links, such as http://localhost.

Development

If you want to contribute to this project, read the CONTRIBUTING.md file for hints on how to submit pull requests.