add initial working example

.dockerignore

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+*
+!target/*-runner
+!target/*-runner.jar
+!target/lib/*
+!target/quarkus-app/*

.gitignore

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+#Maven
+target/
+pom.xml.tag
+pom.xml.releaseBackup
+pom.xml.versionsBackup
+release.properties
+.flattened-pom.xml
+
+# Eclipse
+.project
+.classpath
+.settings/
+bin/
+
+# IntelliJ
+.idea
+*.ipr
+*.iml
+*.iws
+
+# NetBeans
+nb-configuration.xml
+
+# Visual Studio Code
+.vscode
+.factorypath
+
+# OSX
+.DS_Store
+
+# Vim
+*.swp
+*.swo
+
+# patch
+*.orig
+*.rej
+
+# Local environment
+.env

.mvn/wrapper/.gitignore

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+maven-wrapper.jar

.mvn/wrapper/MavenWrapperDownloader.java

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+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+import java.net.*;
+import java.io.*;
+import java.nio.channels.*;
+import java.util.Properties;
+
+public class MavenWrapperDownloader
+{
+    private static final String WRAPPER_VERSION = "3.1.1";
+
+    /**
+     * Default URL to download the maven-wrapper.jar from, if no 'downloadUrl' is provided.
+     */
+    private static final String DEFAULT_DOWNLOAD_URL =
+        "https://repo.maven.apache.org/maven2/org/apache/maven/wrapper/maven-wrapper/" + WRAPPER_VERSION
+            + "/maven-wrapper-" + WRAPPER_VERSION + ".jar";
+
+    /**
+     * Path to the maven-wrapper.properties file, which might contain a downloadUrl property to use instead of the
+     * default one.
+     */
+    private static final String MAVEN_WRAPPER_PROPERTIES_PATH = ".mvn/wrapper/maven-wrapper.properties";
+
+    /**
+     * Path where the maven-wrapper.jar will be saved to.
+     */
+    private static final String MAVEN_WRAPPER_JAR_PATH = ".mvn/wrapper/maven-wrapper.jar";
+
+    /**
+     * Name of the property which should be used to override the default download url for the wrapper.
+     */
+    private static final String PROPERTY_NAME_WRAPPER_URL = "wrapperUrl";
+
+    public static void main( String args[] )
+    {
+        System.out.println( "- Downloader started" );
+        File baseDirectory = new File( args[0] );
+        System.out.println( "- Using base directory: " + baseDirectory.getAbsolutePath() );
+
+        // If the maven-wrapper.properties exists, read it and check if it contains a custom
+        // wrapperUrl parameter.
+        File mavenWrapperPropertyFile = new File( baseDirectory, MAVEN_WRAPPER_PROPERTIES_PATH );
+        String url = DEFAULT_DOWNLOAD_URL;
+        if ( mavenWrapperPropertyFile.exists() )
+        {
+            FileInputStream mavenWrapperPropertyFileInputStream = null;
+            try
+            {
+                mavenWrapperPropertyFileInputStream = new FileInputStream( mavenWrapperPropertyFile );
+                Properties mavenWrapperProperties = new Properties();
+                mavenWrapperProperties.load( mavenWrapperPropertyFileInputStream );
+                url = mavenWrapperProperties.getProperty( PROPERTY_NAME_WRAPPER_URL, url );
+            }
+            catch ( IOException e )
+            {
+                System.out.println( "- ERROR loading '" + MAVEN_WRAPPER_PROPERTIES_PATH + "'" );
+            }
+            finally
+            {
+                try
+                {
+                    if ( mavenWrapperPropertyFileInputStream != null )
+                    {
+                        mavenWrapperPropertyFileInputStream.close();
+                    }
+                }
+                catch ( IOException e )
+                {
+                    // Ignore ...
+                }
+            }
+        }
+        System.out.println( "- Downloading from: " + url );
+
+        File outputFile = new File( baseDirectory.getAbsolutePath(), MAVEN_WRAPPER_JAR_PATH );
+        if ( !outputFile.getParentFile().exists() )
+        {
+            if ( !outputFile.getParentFile().mkdirs() )
+            {
+                System.out.println( "- ERROR creating output directory '" + outputFile.getParentFile().getAbsolutePath()
+                    + "'" );
+            }
+        }
+        System.out.println( "- Downloading to: " + outputFile.getAbsolutePath() );
+        try
+        {
+            downloadFileFromURL( url, outputFile );
+            System.out.println( "Done" );
+            System.exit( 0 );
+        }
+        catch ( Throwable e )
+        {
+            System.out.println( "- Error downloading" );
+            e.printStackTrace();
+            System.exit( 1 );
+        }
+    }
+
+    private static void downloadFileFromURL( String urlString, File destination )
+        throws Exception
+    {
+        if ( System.getenv( "MVNW_USERNAME" ) != null && System.getenv( "MVNW_PASSWORD" ) != null )
+        {
+            String username = System.getenv( "MVNW_USERNAME" );
+            char[] password = System.getenv( "MVNW_PASSWORD" ).toCharArray();
+            Authenticator.setDefault( new Authenticator()
+            {
+                @Override
+                protected PasswordAuthentication getPasswordAuthentication()
+                {
+                    return new PasswordAuthentication( username, password );
+                }
+            } );
+        }
+        URL website = new URL( urlString );
+        ReadableByteChannel rbc;
+        rbc = Channels.newChannel( website.openStream() );
+        FileOutputStream fos = new FileOutputStream( destination );
+        fos.getChannel().transferFrom( rbc, 0, Long.MAX_VALUE );
+        fos.close();
+        rbc.close();
+    }
+
+}

.mvn/wrapper/maven-wrapper.properties

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+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+distributionUrl=https://repo.maven.apache.org/maven2/org/apache/maven/apache-maven/3.8.6/apache-maven-3.8.6-bin.zip
+wrapperUrl=https://repo.maven.apache.org/maven2/org/apache/maven/wrapper/maven-wrapper/3.1.1/maven-wrapper-3.1.1.jar

README.md

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+# Quarkus Programmatic Datasource Configuration
+
+I couldn't find any direct examples to how to programmatically configure a datasource with Quarkus in the docs, only
+a reference to [TenantConnectionResolver][0] and a [GitHub issue asking about it][1]. Armed with these helpful, albeit
+vague tips, I figured out how to do it and made this example app to demonstrate it.
+
+Every time a request is made to the `/test` endpoint, the app generates a new H2 database and inserts a `TestEntity` into it.
+
+The Quarkus docs and terminology refer to this capability in the context of multi-tenancy, which makes sense. However, being
+able to programmatically create/resolve datasources is conceivably useful for other purposes as well. For example, the whole
+reason I started researching how to do this was because I wanted to create an app which used sqlite as a datasource, and the sqlite
+file itself could be located in multiple places.
+
+I have tried to annotate the respective configuration and code with comments for specific details of why that code or configuration is
+necessary. If you still have questions after reading through them though, feel free to open up an issue and I will attempt
+to help clarify any confusing parts.
+
+[0]: https://quarkus.io/guides/hibernate-orm#programmatically-resolving-tenants-connections
+[1]: https://github.com/quarkusio/quarkus/issues/7019
+
+## Quarkus auto-generated docs
+
+## quarkus-programmatic-datasource-configuration Project
+
+This project uses Quarkus, the Supersonic Subatomic Java Framework.
+
+If you want to learn more about Quarkus, please visit its website: https://quarkus.io/ .
+
+### Running the application in dev mode
+
+You can run your application in dev mode that enables live coding using:
+```shell script
+./mvnw compile quarkus:dev
+```
+
+> **_NOTE:_**  Quarkus now ships with a Dev UI, which is available in dev mode only at http://localhost:8080/q/dev/.
+
+### Packaging and running the application
+
+The application can be packaged using:
+```shell script
+./mvnw package
+```
+It produces the `quarkus-run.jar` file in the `target/quarkus-app/` directory.
+Be aware that it’s not an _über-jar_ as the dependencies are copied into the `target/quarkus-app/lib/` directory.
+
+The application is now runnable using `java -jar target/quarkus-app/quarkus-run.jar`.
+
+If you want to build an _über-jar_, execute the following command:
+```shell script
+./mvnw package -Dquarkus.package.type=uber-jar
+```
+
+The application, packaged as an _über-jar_, is now runnable using `java -jar target/*-runner.jar`.
+
+### Creating a native executable
+
+You can create a native executable using: 
+```shell script
+./mvnw package -Pnative
+```
+
+Or, if you don't have GraalVM installed, you can run the native executable build in a container using: 
+```shell script
+./mvnw package -Pnative -Dquarkus.native.container-build=true
+```
+
+You can then execute your native executable with: `./target/quarkus-programmatic-datasource-configuration-1.0.0-SNAPSHOT-runner`
+
+If you want to learn more about building native executables, please consult https://quarkus.io/guides/maven-tooling.
+
+### Provided Code
+
+#### RESTEasy Reactive
+
+Easily start your Reactive RESTful Web Services
+
+[Related guide section...](https://quarkus.io/guides/getting-started-reactive#reactive-jax-rs-resources)