Make Quarkus restart when a change to Flyway scripts is made

Adds watches to any existing Flyway migration scripts. This doesn't yet fully address #25256 (as this issue primarily is about the use case of adding new migration scripts), but at least the developer can now continue editing existing migration scripts.

Related issue: #25256

(cherry picked from commit 913308b)

docs/src/main/asciidoc/flyway.adoc

@@ -15,7 +15,7 @@ Quarkus provides first class support for using Flyway as will be explained in th
 
 == Setting up support for Flyway
 
-To start using Flyway with your project, you just need to:
+As shown in the <<developing-with-flyway>> section, to start using Flyway with your project, you just need to:
 
 * add your migrations to the `{migrations-path}` folder as you usually do with Flyway
 * activate the `migrate-at-start` option to migrate the schema automatically or inject the `Flyway` object and run
@@ -77,6 +77,7 @@ Also, you can customize the Flyway behaviour by using the following properties:
 
 include::{generated-dir}/config/quarkus-flyway.adoc[opts=optional, leveloffset=+1]
 
+== Developing with Flyway
 
 The following is an example for the `{config-file}` file:
 
@@ -88,10 +89,10 @@ quarkus.datasource.username=sarah
 quarkus.datasource.password=connor
 quarkus.datasource.jdbc.url=jdbc:postgresql://localhost:5432/mydatabase
 
-# Flyway minimal config properties
+# Run Flyway migrations automatically
 quarkus.flyway.migrate-at-start=true
 
-# Flyway optional config properties
+# More Flyway configuration options
 # quarkus.flyway.baseline-on-migrate=true
 # quarkus.flyway.baseline-version=1.0.0
 # quarkus.flyway.baseline-description=Initial version
@@ -116,7 +117,12 @@ INSERT INTO quarkus(id, name)
 VALUES (1, 'QUARKED');
 ----
 
-Now you can start your application and Quarkus will run the Flyway's migrate method according to your config:
+Now you can start your application and Quarkus will run the Flyway's
+migrate method according to your config.
+
+NOTE: With `quarkus.flyway.migrate-at-start=true`, as in the example
+above, Quarkus will execute the Flyway migration as part of the
+xref:lifecycle.adoc[application startup].
 
 [source,java]
 ----
@@ -132,9 +138,14 @@ public class MigrationService {
     }
 }
 ----
-
 <1> Inject the Flyway object if you want to use it directly
 
+TIP: In dev-mode Quarkus will automatically restart the application if
+any of the existing migration scripts get modified. If you want to take
+advantage of this while developing and testing new migration scripts,
+you will want to set `%dev.quarkus.flyway.clean-at-start=true`, so that
+Flyway actually runs the modified migration.
+
 == Multiple datasources
 
 Flyway can be configured for multiple datasources.
@@ -182,9 +193,6 @@ NOTE: Without configuration, Flyway is set up for every datasource using the def
 
 In case you are interested in using the `Flyway` object directly, you can inject it as follows:
 
-NOTE: If you enabled the `quarkus.flyway.migrate-at-start` property, by the time you use the Flyway instance,
-Quarkus will already have run the migrate operation
-
 [source,java]
 ----
 @ApplicationScoped

docs/src/main/asciidoc/hibernate-orm.adoc

@@ -555,7 +555,7 @@ link in the Flyway pane. Hit the `Create Initial Migration` button and the follo
 - A `db/migration/V1.0.0__\{appname\}.sql` file will be created, containing the SQL Hibernate is running to generate the schema
 - `quarkus.flyway.baseline-on-migrate` will be set, telling Flyway to automatically create its baseline tables
 - `quarkus.flyway.migrate-at-start` will be set, telling Flyway to automatically apply migrations on application startup
-- `%dev.quarkus.flyway.clean-at-start` and ``%test.quarkus.flyway.clean-at-start` will be set, to clean the DB after reload in dev/test mode
+- `%dev.quarkus.flyway.clean-at-start` and `%test.quarkus.flyway.clean-at-start` will be set, to clean the DB after reload in dev/test mode
 
 WARNING: This button is simply a convenience to quickly get you started with Flyway, it is up to you to determine how you want to
 manage your database schemas in production. In particular the `migrate-at-start` setting may not be right for all environments.

extensions/flyway/deployment/src/main/java/io/quarkus/flyway/FlywayProcessor.java

@@ -45,6 +45,7 @@
 import io.quarkus.deployment.annotations.Record;
 import io.quarkus.deployment.builditem.CombinedIndexBuildItem;
 import io.quarkus.deployment.builditem.FeatureBuildItem;
+import io.quarkus.deployment.builditem.HotDeploymentWatchedFileBuildItem;
 import io.quarkus.deployment.builditem.IndexDependencyBuildItem;
 import io.quarkus.deployment.builditem.ServiceStartBuildItem;
 import io.quarkus.deployment.builditem.nativeimage.NativeImageResourceBuildItem;
@@ -81,6 +82,7 @@ IndexDependencyBuildItem indexFlyway() {
     MigrationStateBuildItem build(BuildProducer<FeatureBuildItem> featureProducer,
             BuildProducer<NativeImageResourceBuildItem> resourceProducer,
             BuildProducer<ReflectiveClassBuildItem> reflectiveClassProducer,
+            BuildProducer<HotDeploymentWatchedFileBuildItem> hotDeploymentProducer,
             FlywayRecorder recorder,
             RecorderContext context,
             CombinedIndexBuildItem combinedIndexBuildItem,
@@ -107,6 +109,9 @@ MigrationStateBuildItem build(BuildProducer<FeatureBuildItem> featureProducer,
 
         Collection<String> applicationMigrations = applicationMigrationsToDs.values().stream().collect(HashSet::new,
                 AbstractCollection::addAll, HashSet::addAll);
+        for (String applicationMigration : applicationMigrations) {
+            hotDeploymentProducer.produce(new HotDeploymentWatchedFileBuildItem(applicationMigration));
+        }
         recorder.setApplicationMigrationFiles(applicationMigrations);
 
         Set<Class<? extends JavaMigration>> javaMigrationClasses = new HashSet<>();

extensions/flyway/deployment/src/test/java/io/quarkus/flyway/test/FlywayDevModeModifyMigrationTest.java

@@ -0,0 +1,58 @@
+package io.quarkus.flyway.test;
+
+import static org.hamcrest.Matchers.is;
+
+import java.sql.Connection;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.sql.Statement;
+import java.util.function.Function;
+
+import javax.inject.Inject;
+import javax.ws.rs.GET;
+import javax.ws.rs.Path;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.RegisterExtension;
+
+import io.agroal.api.AgroalDataSource;
+import io.quarkus.test.QuarkusDevModeTest;
+import io.restassured.RestAssured;
+
+public class FlywayDevModeModifyMigrationTest {
+
+    @RegisterExtension
+    static final QuarkusDevModeTest config = new QuarkusDevModeTest()
+            .withApplicationRoot((jar) -> jar
+                    .addClasses(RowCountEndpoint.class)
+                    .addAsResource("db/migration/V1.0.0__Quarkus.sql")
+                    .addAsResource("clean-and-migrate-at-start-config.properties", "application.properties"));
+
+    @Test
+    public void testModifyingExistingMigrationScriptCausesRestart() {
+        RestAssured.get("/row-count").then().statusCode(200).body(is("0"));
+        config.modifyResourceFile("db/migration/V1.0.0__Quarkus.sql", new Function<String, String>() {
+            @Override
+            public String apply(String s) {
+                return s + '\n' + "INSERT INTO quarked_flyway VALUES (1001, 'test')";
+            }
+        });
+        RestAssured.get("/row-count").then().statusCode(200).body(is("1"));
+    }
+
+    @Path("/row-count")
+    public static class RowCountEndpoint {
+
+        @Inject
+        AgroalDataSource dataSource;
+
+        @GET
+        public int rowCount() throws SQLException {
+            try (Connection connection = dataSource.getConnection(); Statement stat = connection.createStatement()) {
+                try (ResultSet countQuery = stat.executeQuery("select count(1) from quarked_flyway")) {
+                    return countQuery.first() ? countQuery.getInt(1) : 0;
+                }
+            }
+        }
+    }
+}