how-to-configure-module-build-options.md

title	description	author	ms.author	ms.date	ms.topic	ms.service	services
Configure module build options	Learn how to use the module.json file to configure build and deployment options for a module	PatAltimore	patricka	03/11/2022	how-to	iot-edge	iot-edge

Configure IoT Edge module build options

[!INCLUDE iot-edge-version-all-supported]

The module.json file controls how modules are built and deployed. IoT Edge module Visual Studio and Visual Studio Code projects include the module.json file. The file contains IoT Edge module configuration details including the version and platform that is used when building an IoT Edge module.

module.json settings

The module.json file includes the following settings:

Setting	Description
image.repository	The repository of the module.
image.tag.version	The version of the module.
image.tag.platforms	A list of supported platforms and their corresponding dockerfile. Each entry is a platform key and dockerfile pair <platform key>:<dockerfile>.
image.buildOptions	The build arguments used when running docker build.
image.contextPath	The context path used when running docker build. By default, it's the current folder of the module.json file. If your Docker build needs files not included in the current folder such as a reference to an external package or project, set the contextPath to the root path of all necessary files. Verify the files are copied in the dockerfile.
language	The programming language of the module.

For example, the following module.json file is for a C# IoT Edge module:

{
    "$schema-version": "0.0.1",
    "description": "",
    "image": {
        "repository": "localhost:5000/edgemodule",
        "tag": {
            "version": "0.0.1",
            "platforms": {
                "amd64": "./Dockerfile.amd64", 
                "amd64.debug": "./Dockerfile.amd64.debug",
                "arm32v7": "./Dockerfile.arm32v7",
                "arm32v7.debug": "./Dockerfile.arm32v7.debug",
                "arm64v8": "./Dockerfile.arm64v8",
                "arm64v8.debug": "./Dockerfile.arm64v8.debug",
                "windows-amd64": "./Dockerfile.windows-amd64"
            }
        },
        "buildOptions": ["--add-host=docker:10.180.0.1"],
        "contextPath": "./"
    },
    "language": "csharp"
}

Once the module is built, the final tag of the image is combined with both version and platform as <repository>:<version>-<platform key>. For this example, the image tag for amd64.debug is localhost:5000/csharpmod:0.0.1-amd64.debug.

Next steps

Understand the requirements and tools for developing IoT Edge modules