allow to set initial and max RAM percentage usage

README.md

@@ -103,6 +103,23 @@ KeycloakContainer keycloak = new KeycloakContainer()
     .withContextPath("/auth");
 ```
 
+### Memory Settings
+
+As of Keycloak 24 the container doesn't use an absolute amount of memory, but a relative percentage of the overall available memory to the container, [see also here](https://www.keycloak.org/server/containers#_specifying_different_memory_settings).
+
+This testcontainer has an initial memory setting of
+
+    JAVA_OPTS_KC_HEAP="-XX:InitialRAMPercentage=1 -XX:MaxRAMPercentage=5"
+
+to not overload your environment.
+You can override this settng with the `withRamPercentage(initial, max)` method:
+
+```java
+@Container
+KeycloakContainer keycloak = new KeycloakContainer()
+    .withRamPercentage(50, 70);
+```
+
 ## TLS (SSL) Usage
 
 You have three options to use HTTPS/TLS secured communication with your Keycloak Testcontainer.

src/main/java/dasniko/testcontainers/keycloak/ExtendableKeycloakContainer.java

@@ -64,6 +64,8 @@ public abstract class ExtendableKeycloakContainer<SELF extends ExtendableKeycloa
     private static final int KEYCLOAK_PORT_HTTPS = 8443;
     private static final int KEYCLOAK_PORT_DEBUG = 8787;
     private static final Duration DEFAULT_STARTUP_TIMEOUT = Duration.ofMinutes(2);
+    private static final int DEFAULT_INITIAL_RAM_PERCENTAGE = 1;
+    private static final int DEFAULT_MAX_RAM_PERCENTAGE = 5;
 
     private static final String KEYCLOAK_ADMIN_USER = "admin";
     private static final String KEYCLOAK_ADMIN_PASSWORD = "admin";
@@ -79,6 +81,8 @@ public abstract class ExtendableKeycloakContainer<SELF extends ExtendableKeycloa
     private String adminUsername = KEYCLOAK_ADMIN_USER;
     private String adminPassword = KEYCLOAK_ADMIN_PASSWORD;
     private String contextPath = KEYCLOAK_CONTEXT_PATH;
+    private int initialRamPercentage = DEFAULT_INITIAL_RAM_PERCENTAGE;
+    private int maxRamPercentage = DEFAULT_MAX_RAM_PERCENTAGE;
 
     private final Set<String> importFiles;
     private String tlsCertificateFilename;
@@ -151,6 +155,7 @@ protected void configure() {
 
         withEnv("KEYCLOAK_ADMIN", adminUsername);
         withEnv("KEYCLOAK_ADMIN_PASSWORD", adminPassword);
+        withEnv("JAVA_OPTS_KC_HEAP", "-XX:InitialRAMPercentage=%d -XX:MaxRAMPercentage=%d".formatted(initialRamPercentage, maxRamPercentage));
 
         if (useTls && isNotBlank(tlsCertificateFilename)) {
             String tlsCertFilePath = "/opt/keycloak/conf/tls.crt";
@@ -303,6 +308,12 @@ public SELF withContextPath(String contextPath) {
         return self();
     }
 
+    public SELF withRamPercentage(int initialRamPercentage, int maxRamPercentage) {
+        this.initialRamPercentage = initialRamPercentage;
+        this.maxRamPercentage = maxRamPercentage;
+        return self();
+    }
+
     /**
      * Exposes the given classes location as an exploded providers.jar.
      *

src/test/resources/junit-platform.properties

@@ -1,3 +1,4 @@
-junit.jupiter.execution.parallel.enabled = true
+junit.jupiter.execution.parallel.enabled = false
+junit.jupiter.execution.parallel.config.fixed.parallelism = 5
 junit.jupiter.execution.parallel.mode.default = concurrent
 junit.jupiter.execution.parallel.mode.classes.default = same_thread