Shorten fallback to another strategy (#4386)

* Removed double check of configured Docker client strategy.
* Shortened the ping timeout (when choosing docker client) to 5 seconds.
* Added `client.ping.timeout` configuration option.
* Made relevant change in the docs.

Author: pioorg

core/src/main/java/org/testcontainers/dockerclient/DockerClientProviderStrategy.java

@@ -111,10 +111,11 @@ public static DockerClientProviderStrategy getFirstValidStrategy(List<DockerClie
 
         List<String> configurationFailures = new ArrayList<>();
 
+        String dockerClientStrategyClassName = TestcontainersConfiguration.getInstance().getDockerClientStrategyClassName();
         return Stream
                 .concat(
                         Stream
-                                .of(TestcontainersConfiguration.getInstance().getDockerClientStrategyClassName())
+                                .of(dockerClientStrategyClassName)
                                 .filter(Objects::nonNull)
                                 .flatMap(it -> {
                                     try {
@@ -136,6 +137,7 @@ public static DockerClientProviderStrategy getFirstValidStrategy(List<DockerClie
                                 .peek(strategy -> log.info("Loaded {} from ~/.testcontainers.properties, will try it first", strategy.getClass().getName())),
                         strategies
                                 .stream()
+                                .filter(it -> !it.getClass().getCanonicalName().equals(dockerClientStrategyClassName))
                                 .filter(DockerClientProviderStrategy::isApplicable)
                                 .sorted(Comparator.comparing(DockerClientProviderStrategy::getPriority).reversed())
                 )
@@ -145,7 +147,7 @@ public static DockerClientProviderStrategy getFirstValidStrategy(List<DockerClie
 
                         Info info;
                         try {
-                            info = Unreliables.retryUntilSuccess(30, TimeUnit.SECONDS, () -> {
+                            info = Unreliables.retryUntilSuccess(TestcontainersConfiguration.getInstance().getClientPingTimeout(), TimeUnit.SECONDS, () -> {
                                 return strategy.PING_RATE_LIMITER.getWhenReady(() -> {
                                     log.debug("Pinging docker daemon...");
                                     return dockerClient.infoCmd().exec();

core/src/main/java/org/testcontainers/utility/TestcontainersConfiguration.java

@@ -210,6 +210,10 @@ public String getImageSubstitutorClassName() {
         return getEnvVarOrProperty("image.substitutor", null);
     }
 
+    public Integer getClientPingTimeout() {
+        return Integer.parseInt(getEnvVarOrProperty("client.ping.timeout", "5"));
+    }
+
     @Nullable
     @Contract("_, !null, _ -> !null")
     private String getConfigurable(@NotNull final String propertyName, @Nullable final String defaultValue, Properties... propertiesSources) {

docs/features/configuration.md

@@ -94,6 +94,11 @@ but does not allow starting privileged containers, you can turn off the Ryuk con
 > **pull.pause.timeout = 30**
 > By default Testcontainers will abort the pull of an image if the pull appears stalled (no data transferred) for longer than this duration (in seconds).
 
+## Customizing client ping behaviour
+
+> **client.ping.timeout = 5**
+> Specifies for how long Testcontainers will try to connect to the Docker client to obtain valid info about the client before giving up and trying next strategy, if applicable (in seconds).
+
 ## Customizing Docker host detection
 
 Testcontainers will attempt to detect the Docker environment and configure everything to work automatically.