Ensure that an uppercase username doesn't break container-image building

extensions/container-image/container-image-jib/deployment/src/main/java/io/quarkus/container/image/jib/deployment/JibProcessor.java

@@ -189,7 +189,7 @@ private ImageReference getImageReference(ContainerImageConfig containerImageConf
             throw new IllegalArgumentException("The supplied container-image registry '" + registry + "' is invalid");
         }
 
-        String repository = (containerImageConfig.group.map(s -> s + "/").orElse(""))
+        String repository = (containerImageConfig.getEffectiveGroup().map(s -> s + "/").orElse(""))
                 + containerImageConfig.name.orElse(applicationInfo.getName());
         if (!ImageReference.isValidRepository(repository)) {
             throw new IllegalArgumentException("The supplied container-image repository '" + repository + "' is invalid");

extensions/container-image/deployment/pom.xml

@@ -21,6 +21,12 @@
             <groupId>io.quarkus</groupId>
             <artifactId>quarkus-container-image-spi</artifactId>
         </dependency>
+
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter</artifactId>
+            <scope>test</scope>
+        </dependency>
     </dependencies>
 
     <build>

extensions/container-image/deployment/src/main/java/io/quarkus/container/image/deployment/ContainerImageConfig.java

@@ -61,4 +61,20 @@ public class ContainerImageConfig {
      */
     @ConfigItem
     public boolean push;
+
+    /**
+     * Since user.name which is default value can be uppercase and uppercase values are not allowed
+     * in the repository part of image references, we need to make the username lowercase.
+     *
+     * We purposely don't change the value of an explicitly set group.
+     */
+    public Optional<String> getEffectiveGroup() {
+        if (group.isPresent()) {
+            String originalGroup = group.get();
+            if (originalGroup.equals(System.getProperty("user.name"))) {
+                return Optional.of(originalGroup.toLowerCase());
+            }
+        }
+        return group;
+    }
 }

extensions/container-image/deployment/src/main/java/io/quarkus/container/image/deployment/ContainerProcessor.java

@@ -14,7 +14,7 @@ public ContainerImageInfoBuildItem publishImageInfo(ApplicationInfoBuildItem app
         ensureSingleContainerImageExtension(capabilities);
 
         return new ContainerImageInfoBuildItem(containerImageConfig.registry,
-                containerImageConfig.group,
+                containerImageConfig.getEffectiveGroup(),
                 containerImageConfig.name.orElse(app.getName()),
                 containerImageConfig.tag.orElse(app.getVersion()));
     }

extensions/container-image/deployment/src/test/java/io/quarkus/container/image/deployment/ContainerImageConfigEffectiveGroupTest.java

@@ -0,0 +1,47 @@
+package io.quarkus.container.image.deployment;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.util.Optional;
+
+import org.junit.jupiter.api.Test;
+
+class ContainerImageConfigEffectiveGroupTest {
+
+    public static final String USER_NAME_SYSTEM_PROPERTY = "user.name";
+
+    private ContainerImageConfig sut = new ContainerImageConfig();
+
+    @Test
+    void testFromLowercaseUsername() {
+        testWithNewUsername("test", () -> {
+            sut.group = Optional.of(System.getProperty(USER_NAME_SYSTEM_PROPERTY));
+            assertEquals(sut.getEffectiveGroup(), Optional.of("test"));
+        });
+    }
+
+    @Test
+    void testFromUppercaseUsername() {
+        testWithNewUsername("TEST", () -> {
+            sut.group = Optional.of(System.getProperty(USER_NAME_SYSTEM_PROPERTY));
+            assertEquals(sut.getEffectiveGroup(), Optional.of("test"));
+        });
+    }
+
+    @Test
+    void testFromOther() {
+        testWithNewUsername("WhateveR", () -> {
+            sut.group = Optional.of("OtheR");
+            assertEquals(sut.getEffectiveGroup(), Optional.of("OtheR"));
+        });
+    }
+
+    private void testWithNewUsername(String newUserName, Runnable test) {
+        String previousUsernameValue = System.getProperty(USER_NAME_SYSTEM_PROPERTY);
+        System.setProperty(USER_NAME_SYSTEM_PROPERTY, newUserName);
+
+        test.run();
+
+        System.setProperty(USER_NAME_SYSTEM_PROPERTY, previousUsernameValue);
+    }
+}