Azure function: confusion about remote build and run from package

Reading through the documents of Azure function:

Deployment options

Run from package file

I have some confusions that need to be clarified:

In Remote build, it says:

> When apps are built remotely on Linux, they run from the deployment package.

To Enable functions to run from a package:

> To enable your function app to run from a package, add a
> WEBSITE_RUN_FROM_PACKAGE setting to your function app settings. The
> WEBSITE_RUN_FROM_PACKAGE setting can have one of the following values:
>
> and 1 is recommended for premium plan

And in general considerations, it says in the last bullet point:

> If your project needs to use remote build, don't use the
> WEBSITE_RUN_FROM_PACKAGE app setting. Instead add the
> SCM_DO_BUILD_DURING_DEPLOYMENT=true deployment customization app
> setting. For Linux, also add the ENABLE_ORYX_BUILD=true setting.

Isn't there a contradiction?

1. In Linux, when remote build, they run from deployment package.

2. To enable to run from package, we need WEBSITE_RUN_FROM_PACKAGE=1

3. But, If your project needs to use remote build, don't use the WEBSITE_RUN_FROM_PACKAGE app setting.

I must have got my concepts wrong. Could someone offer some clarification?

To sort things out, I want to clarify a few questions:

1. When Azure performs remote build, what is the resultant file of the build process? What is the format of the file? Where exactly is this file stored?

Remote build while doing the zip deployment refers to building the function app's code on a remote build server.

This is used in case if you any dependencies in your function app which needs to be compiled or requires additional build steps before getting deployed.

Remote build with SCM_DO_BUILD_DURING_DEPLOYMENT=true and ENABLE_ORYX_BUILD=true:

1. When you deploy your function to Azure, it uses a remote build server to build your function app which is equipped with the required build tools, runtime environments, and dependencies to compile and package your code correctly.

2. The remote build server compiles the code by installing required dependencies and packages into a deployment package and deploy the package to your Azure Function App runtime environment.

3. When your function app is invoked, it runs directly from the deployment package that was built on the remote server with all the dependencies and compiled code to execute the function properly.

As the app is built remotely and deployed as a package, it already runs from the deployment package. So, adding the setting WEBSITE_RUN_FROM_PACKAGE manually isn't required.

WEBSITE_RUN_FROM_PACKAGE(without remote build):

Running from a package refers to the function app's use of the deployment package's contents during runtime in both cases. However, the way the deployment package is created and managed differs between remote build and zip deployment scenarios.

1. While deploying the function using zip deployment, the function app's source code, dependencies, and al the required files will be packaged into a zip file. Then, the zip file is uploaded to the Function's target environment in Azure. After that, Azure deploys the contents to your function app's runtime environment.

2. Generally, Azure Functions tries to run directly from the source code location(site/wwwroot).

3. The setting WEBSITE_RUN_FROM_PACKAGE=1 in function app=>settings=>configuration lets Azure to run the app from the uploaded deployment package which was uploaded through zip deployment instead of source code.

>1. When Azure performs remote build, what is the resultant file of the build process? What is the format of the file? Where exactly is this file stored?

To check the files of your function app after remote build:

• Go to KUDU site of your function app, Debug Console=>Bash
• Navigate to the path data\SitePackages as shown below:
• The function related zip files will be available along with the packagename.txt.

To check the files of your function app(without remote build/ Zip deployment):