Fix fabric8io#1060: Smarter API version handling

Send a test request to the Daemon, and check whether it succeeds. In the return response
there's a header Api-Version: which holds the actual Docker daemon version. If this test
request because of a too low version, we can just pick up that version and use it as
minimal version for us.

src/main/java/io/fabric8/maven/docker/access/UrlBuilder.java

@@ -187,7 +187,7 @@ private static String encode(String param) {
         }
     }
 
-    private String stripSlash(String url) {
+    public static String stripSlash(String url) {
         String ret = url;
         while (ret.endsWith("/")) {
             ret = ret.substring(0, ret.length() - 1);

src/main/java/io/fabric8/maven/docker/access/hc/DockerAccessWithHcClient.java

@@ -5,6 +5,7 @@
 import com.google.gson.JsonObject;
 
 import org.apache.commons.io.IOUtils;
+import org.apache.http.HttpHeaders;
 import org.apache.http.HttpResponse;
 import org.apache.http.client.HttpResponseException;
 import org.apache.http.client.ResponseHandler;
@@ -58,6 +59,8 @@
 import io.fabric8.maven.docker.util.ImageName;
 import io.fabric8.maven.docker.util.Logger;
 import io.fabric8.maven.docker.util.Timestamp;
+import org.apache.http.client.methods.CloseableHttpResponse;
+import org.apache.http.client.methods.HttpGet;
 
 import static java.net.HttpURLConnection.HTTP_CREATED;
 import static java.net.HttpURLConnection.HTTP_INTERNAL_ERROR;
@@ -105,26 +108,25 @@ public class DockerAccessWithHcClient implements DockerAccess {
      * @param log      a log handler for printing out logging information
      * @paran usePool  whether to use a connection bool or not
      */
-    public DockerAccessWithHcClient(String apiVersion,
-                                    String baseUrl,
+    public DockerAccessWithHcClient(String baseUrl,
                                     String certPath,
                                     int maxConnections,
                                     Logger log) throws IOException {
-        this.log = log;
         URI uri = URI.create(baseUrl);
         if (uri.getScheme() == null) {
             throw new IllegalArgumentException("The docker access url '" + baseUrl + "' must contain a schema tcp://, unix:// or npipe://");
         }
         if (uri.getScheme().equalsIgnoreCase("unix")) {
             this.delegate = createHttpClient(new UnixSocketClientBuilder(uri.getPath(), maxConnections, log));
-            this.urlBuilder = new UrlBuilder(UNIX_URL, apiVersion);
+            baseUrl = UNIX_URL;
         } else if (uri.getScheme().equalsIgnoreCase("npipe")) {
-        	this.delegate = createHttpClient(new NamedPipeClientBuilder(uri.getPath(), maxConnections, log), false);
-            this.urlBuilder = new UrlBuilder(NPIPE_URL, apiVersion);
+            this.delegate = createHttpClient(new NamedPipeClientBuilder(uri.getPath(), maxConnections, log), false);
+            baseUrl = NPIPE_URL;
         } else {
             this.delegate = createHttpClient(new HttpClientBuilder(isSSL(baseUrl) ? certPath : null, maxConnections));
-            this.urlBuilder = new UrlBuilder(baseUrl, apiVersion);
         }
+        this.urlBuilder = new UrlBuilder(baseUrl, "v" + fetchApiVersionFromServer(UrlBuilder.stripSlash(baseUrl), this.delegate));
+        this.log = log;
     }
 
     /** {@inheritDoc} */
@@ -685,7 +687,7 @@ private void logRemoveResponse(JsonArray logElements) {
         }
     }
 
-    private boolean isSSL(String url) {
+    private static boolean isSSL(String url) {
         return url != null && url.toLowerCase().startsWith("https");
     }
 
@@ -707,4 +709,13 @@ public Object handleResponse(HttpResponse response) throws IOException {
             return null;
         }
     }
+
+    public String fetchApiVersionFromServer(String baseUrl, ApacheHttpClientDelegate delegate) throws IOException {
+        HttpGet get = new HttpGet(baseUrl + "/version");
+        get.addHeader(HttpHeaders.ACCEPT, "*/*");
+        get.addHeader(HttpHeaders.CONTENT_TYPE, "application/json");
+        CloseableHttpResponse response = delegate.getHttpClient().execute(get);
+
+        return response.getFirstHeader("Api-Version") != null ? response.getFirstHeader("Api-Version").getValue() : null;
+    }
 }

src/main/java/io/fabric8/maven/docker/service/DockerAccessFactory.java

@@ -36,7 +36,7 @@ public DockerAccess createDockerAccess(DockerAccessContext dockerAccessContext)
             DockerConnectionDetector.ConnectionParameter connectionParam =
                     dockerConnectionDetector.detectConnectionParameter(dockerAccessContext.getDockerHost(), dockerAccessContext.getCertPath());
             String version = dockerAccessContext.getMinimalApiVersion() != null ? dockerAccessContext.getMinimalApiVersion() : API_VERSION;
-            DockerAccess access = new DockerAccessWithHcClient("v" + version, connectionParam.getUrl(),
+            DockerAccess access = new DockerAccessWithHcClient(connectionParam.getUrl(),
                     connectionParam.getCertPath(),
                     dockerAccessContext.getMaxConnections(),
                     dockerAccessContext.getLog());

src/test/java/integration/DockerAccessIT.java

@@ -17,7 +17,6 @@
 import io.fabric8.maven.docker.config.Arguments;
 import io.fabric8.maven.docker.config.DockerMachineConfiguration;
 import io.fabric8.maven.docker.model.Container.PortBinding;
-import io.fabric8.maven.docker.service.DockerAccessFactory;
 import io.fabric8.maven.docker.util.AnsiLogger;
 import io.fabric8.maven.docker.util.Logger;
 
@@ -110,7 +109,7 @@ public void testLoadImage() throws DockerAccessException {
     private DockerAccessWithHcClient createClient(String baseUrl, Logger logger) {
         try {
             String certPath = createDockerConnectionDetector(logger).detectConnectionParameter(null,null).getCertPath();
-            return new DockerAccessWithHcClient("v" + DockerAccessFactory.API_VERSION, baseUrl, certPath, 20, logger);
+            return new DockerAccessWithHcClient(baseUrl, certPath, 20, logger);
         } catch (@SuppressWarnings("unused") IOException e) {
             // not using ssl, so not going to happen
             logger.error(e.getMessage());

src/test/java/integration/DockerAccessWinIT.java

@@ -16,7 +16,6 @@
 import io.fabric8.maven.docker.access.hc.DockerAccessWithHcClient;
 import io.fabric8.maven.docker.config.Arguments;
 import io.fabric8.maven.docker.model.Container.PortBinding;
-import io.fabric8.maven.docker.service.DockerAccessFactory;
 import io.fabric8.maven.docker.util.AnsiLogger;
 import io.fabric8.maven.docker.util.Logger;
 
@@ -98,7 +97,7 @@ public void testPullStartStopRemove() throws DockerAccessException {
     private DockerAccessWithHcClient createClient(String baseUrl, Logger logger) {
         try {
             String certPath = createDockerConnectionDetector(logger).detectConnectionParameter(null, null).getCertPath();
-            return new DockerAccessWithHcClient("v" + DockerAccessFactory.API_VERSION, baseUrl, certPath, 1, logger);
+            return new DockerAccessWithHcClient(baseUrl, certPath, 1, logger);
         } catch (@SuppressWarnings("unused") IOException e) {
             // not using ssl, so not going to happen
             logger.error(e.getMessage());

src/test/java/io/fabric8/maven/docker/access/hc/DockerAccessWithHcClientTest.java

@@ -45,7 +45,7 @@ public class DockerAccessWithHcClientTest {
 
     @Before
     public void setup() throws IOException {
-        client = new DockerAccessWithHcClient("v1.20", "tcp://1.2.3.4:2375", null, 1, mockLogger) {
+        client = new DockerAccessWithHcClient("tcp://1.2.3.4:2375", null, 1, mockLogger) {
             @Override
             ApacheHttpClientDelegate createHttpClient(ClientBuilder builder) throws IOException {
                 return mockDelegate;