How do you read appSettings variables from azure-maven-plugin in Java code?

Is there a way to read the <appSettings> property values in java code ?

https://github.com/microsoft/azure-maven-plugins/wiki/Azure-Functions:-Configuration-Details

I have tried to use System.getProperty but it is not set.

This is not a Spring Boot project.

Is there a way to set environment variables in the azure-maven-plugin ?

My azure-maven-plugin is the following:

       <plugin>
                <groupId>com.microsoft.azure</groupId>
                <artifactId>azure-functions-maven-plugin</artifactId>
                <version>${azure.functions.maven.plugin.version}</version>
                <configuration>
                    <!-- function app name -->
                    <appName>${functionAppName}</appName>
                    <!-- function app resource group -->
                    <resourceGroup>${resourceGroupName}</resourceGroup>
                    <!-- function app service plan name -->
                    <appServicePlanName>${appServicePlanName}</appServicePlanName>
                    <!-- function app region-->
                    <!-- refers https://github.com/microsoft/azure-maven-plugins/wiki/Azure-Functions:-Configuration-Details#supported-regions for all valid values -->
                    <region>${azure.region}</region>
                    <!-- function pricingTier, default to be consumption if not specified -->
                    <!-- refers https://github.com/microsoft/azure-maven-plugins/wiki/Azure-Functions:-Configuration-Details#supported-pricing-tiers for all valid values -->
                    <!-- <pricingTier></pricingTier> -->

                    <!-- Whether to disable application insights, default is false -->
                    <!-- refers https://github.com/microsoft/azure-maven-plugins/wiki/Azure-Functions:-Configuration-Details for all valid configurations for application insights-->
                    <!-- <disableAppInsights></disableAppInsights> -->
                    <runtime>
                        <!-- runtime os, could be windows, linux or docker-->
                        <os>Linux</os>
                        <javaVersion>11</javaVersion>
                        <!-- for docker function, please set the following parameters -->
                        <!-- <image>[hub-user/]repo-name[:tag]</image> -->
                        <!-- <serverId></serverId> -->
                        <!-- <registryUrl></registryUrl>  -->
                    </runtime>
                    <appSettings>
                        <property>
                            <name>FUNCTIONS_EXTENSION_VERSION</name>
                            <value>~4</value>
                        </property>
                    </appSettings>
                </configuration>
                <executions>
                    <execution>
                        <id>package-functions</id>
                        <goals>
                            <goal>package</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>

In an Azure Function App, these application settings are set as environment variables. Therefore, in Java, you can access these settings using System.getenv() rather than System.getProperty().

Here's how you would do it for the FUNCTIONS_EXTENSION_VERSION setting:

String functionsExtensionVersion = System.getenv("FUNCTIONS_EXTENSION_VERSION");
System.out.println("FUNCTIONS_EXTENSION_VERSION: " + functionsExtensionVersion);

When you define settings in the azure-functions-maven-plugin, those settings are applied during the deployment process to Azure. Therefore, when you're running the function locally, the settings you've defined in the Maven configuration won't automatically apply to your local environment. You can either manually set the environment variables on your local machine or If you're using the Azure Functions Core Tools or the Visual Studio/VS Code Azure Functions extension, you can manually add the required application settings (environment variables) to the local.settings.json file

You can use azure cli to set the app configuration value after deploying azure function.

az functionapp config appsettings set --name acmefunction2 --resource-group acmeapp --settings FUNCTIONS_WORKER_RUNTIME=node WEBSITE_RUN_FROM_PACKAGE=1 SCM_DO_BUILD_DURING_DEPLOYMENT=true