Make it possible to turn off Ryuk with an environment variable (#1181)

* Make it possible to turn off Ryuk with an environment variable

* Reverse the condition

* Document how to disable the Ryuk

Author: bsideup

core/src/main/java/org/testcontainers/DockerClientFactory.java

@@ -119,17 +119,35 @@ public DockerClient client() {
                     "  Operating System: " + dockerInfo.getOperatingSystem() + "\n" +
                     "  Total Memory: " + dockerInfo.getMemTotal() / (1024 * 1024) + " MB");
 
-            boolean checksEnabled = !TestcontainersConfiguration.getInstance().isDisableChecks();
-
-            String ryukContainerId = ResourceReaper.start(hostIpAddress, client, checksEnabled);
-            log.info("Ryuk started - will monitor and terminate Testcontainers containers on JVM exit");
+            String ryukContainerId = null;
+            boolean useRyuk = !Boolean.parseBoolean(System.getenv("TESTCONTAINERS_RYUK_DISABLED"));
+            if (useRyuk) {
+                ryukContainerId = ResourceReaper.start(hostIpAddress, client);
+                log.info("Ryuk started - will monitor and terminate Testcontainers containers on JVM exit");
+            }
 
             VisibleAssertions.info("Checking the system...");
 
             checkDockerVersion(version.getVersion());
 
+            boolean checksEnabled = !TestcontainersConfiguration.getInstance().isDisableChecks();
             if (checksEnabled) {
-                checkDiskSpace(client, ryukContainerId);
+                if (ryukContainerId != null) {
+                    checkDiskSpace(client, ryukContainerId);
+                } else {
+                    runInsideDocker(
+                        client,
+                        createContainerCmd -> {
+                            createContainerCmd.withName("testcontainers-checks-" + SESSION_ID);
+                            createContainerCmd.getHostConfig().withAutoRemove(true);
+                            createContainerCmd.withCmd("tail", "-f", "/dev/null");
+                        },
+                        (__, containerId) -> {
+                            checkDiskSpace(client, containerId);
+                            return "";
+                        }
+                    );
+                }
             }
 
             initialized = true;

docs/features/configuration.md

@@ -42,11 +42,20 @@ Some companies disallow the usage of Docker Hub, but you can override `*.image`
 > **kafka.container.image = confluentinc/cp-kafka**  
 > Used by KafkaContainer 
 
-## Customizing ryuk resource reaper
+## Customizing Ryuk resource reaper
 
 > **ryuk.container.image = quay.io/testcontainers/ryuk:0.2.2**
 > The resource reaper is responsible for container removal and automatic cleanup of dead containers at JVM shutdown
 
 > **ryuk.container.privileged = false**
 > In some environments ryuk must be started in privileged mode to work properly (--privileged flag)
 
+### Disabling Ryuk
+Ryuk must be started as a privileged container.  
+If your environment already implements automatic cleanup of containers after the execution,
+but does not allow starting privileged containers, you can turn off the Ryuk container by setting
+`TESTCONTAINERS_RYUK_DISABLED` **environment variable** to `true`.
+
+!!!tip
+    Note that Testcontainers will continue doing the cleanup at JVM's shutdown, unless you `kill -9` your JVM process.
+