Fix the Rootless Docker CI job

.github/workflows/ci-rootless.yml

@@ -7,24 +7,37 @@ on:
 jobs:
   test:
     runs-on: ubuntu-18.04
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - { XDG_RUNTIME_DIR: "" }
+          - { XDG_RUNTIME_DIR: "/tmp/docker-testcontainers/" }
+    env:
+      XDG_RUNTIME_DIR: ${{ matrix.XDG_RUNTIME_DIR }}
     steps:
       - uses: actions/checkout@v2
       - name: debug
         run: id -u; whoami
       - name: uninstall rootful Docker
         run: sudo apt-get -q -y --purge remove moby-engine moby-buildx && sudo rm -rf /var/run/docker.sock
       - name: install rootless Docker
-        run: curl -fsSL https://get.docker.com/rootless | sh
-      - name: start rootless Docker
-        run: PATH=$HOME/bin:$PATH XDG_RUNTIME_DIR=/tmp/docker-$(id -u) dockerd-rootless.sh --experimental --storage-driver vfs &
+        run: |
+          mkdir -p $XDG_RUNTIME_DIR || true
+          curl -fsSL https://get.docker.com/rootless | sh > init.sh
+          cat init.sh
+          source <(grep '^export' init.sh)
+          PATH=$HOME/bin:$PATH dockerd-rootless.sh --experimental --storage-driver vfs &
+          sleep 1
+          DOCKER_HOST=unix://$XDG_RUNTIME_DIR/docker.sock docker info || ls -la $XDG_RUNTIME_DIR
       - name: Build with Gradle
-        run: XDG_RUNTIME_DIR=/tmp/docker-$(id -u) ./gradlew --no-daemon --scan testcontainers:test
+        run: ./gradlew --no-daemon --scan testcontainers:test
       - name: aggregate test reports with ciMate
         if: always()
         continue-on-error: true
         env:
           CIMATE_PROJECT_ID: 2348n4vl
-          CIMATE_CI_KEY: "CI / rootless Docker"
+          CIMATE_CI_KEY: "CI / rootless Docker (${{ matrix.XDG_RUNTIME_DIR }})"
         run: |
           wget -q https://get.cimate.io/release/linux/cimate
           chmod +x cimate

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

@@ -2,28 +2,72 @@
 
 import com.sun.jna.Library;
 import com.sun.jna.Native;
+import lombok.Getter;
+import lombok.extern.slf4j.Slf4j;
+import org.apache.commons.lang.StringUtils;
 import org.apache.commons.lang.SystemUtils;
+import org.jetbrains.annotations.Nullable;
 
 import java.net.URI;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.Paths;
+import java.util.Optional;
 
 /**
  *
  * @deprecated this class is used by the SPI and should not be used directly
  */
 @Deprecated
+@Slf4j
 public final class RootlessDockerClientProviderStrategy extends DockerClientProviderStrategy {
 
     public static final int PRIORITY = UnixSocketClientProviderStrategy.PRIORITY + 1;
 
-    private Path getSocketPath() {
+    @Getter(lazy = true)
+    @Nullable
+    private final Path socketPath = resolveSocketPath();
+
+    private Path resolveSocketPath() {
+        return tryEnv().orElseGet(() -> {
+            Path homePath = Paths.get(System.getProperty("user.home")).resolve(".docker").resolve("run");
+            return tryFolder(homePath).orElseGet(() -> {
+                Path implicitPath = Paths.get("/run/user/" + LibC.INSTANCE.getuid());
+                return tryFolder(implicitPath).orElse(null);
+            });
+        });
+    }
+
+    private Optional<Path> tryEnv() {
         String xdgRuntimeDir = System.getenv("XDG_RUNTIME_DIR");
-        if (xdgRuntimeDir == null) {
-            xdgRuntimeDir = "/run/user/" + LibC.INSTANCE.getuid();
+        if (StringUtils.isBlank(xdgRuntimeDir)) {
+            log.debug("$XDG_RUNTIME_DIR is not set.");
+            return Optional.empty();
+        }
+        Path path = Paths.get(xdgRuntimeDir);
+        if (!Files.exists(path)) {
+            log.debug("$XDG_RUNTIME_DIR is set to '{}' but the folder does not exist.", path);
+            return Optional.empty();
+        }
+        Path socketPath = path.resolve("docker.sock");
+        if (!Files.exists(socketPath)) {
+            log.debug("$XDG_RUNTIME_DIR is set but '{}' does not exist.", socketPath);
+            return Optional.empty();
+        }
+        return Optional.of(socketPath);
+    }
+
+    private Optional<Path> tryFolder(Path path) {
+        if (!Files.exists(path)) {
+            log.debug("'{}' does not exist.", path);
+            return Optional.empty();
+        }
+        Path socketPath = path.resolve("docker.sock");
+        if (!Files.exists(socketPath)) {
+            log.debug("'{}' does not exist.", socketPath);
+            return Optional.empty();
         }
-        return Paths.get(xdgRuntimeDir).resolve("docker.sock");
+        return Optional.of(socketPath);
     }
 
     @Override
@@ -35,7 +79,7 @@ public TransportConfig getTransportConfig() throws InvalidConfigurationException
 
     @Override
     protected boolean isApplicable() {
-        return SystemUtils.IS_OS_LINUX && Files.exists(getSocketPath());
+        return SystemUtils.IS_OS_LINUX && getSocketPath() != null && Files.exists(getSocketPath());
     }
 
     @Override