Support loading auth config for repos with no scheme in their URL

src/main/java/com/spotify/docker/client/DockerConfigReader.java

@@ -31,9 +31,12 @@
 import com.spotify.docker.client.messages.RegistryConfigs;
 import java.io.File;
 import java.io.IOException;
+import java.net.URI;
+import java.net.URISyntaxException;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.Paths;
+import java.util.Arrays;
 import java.util.Map;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -73,9 +76,6 @@ private RegistryAuth parseDockerConfig(final Path configPath, final String serve
     checkNotNull(configPath);
 
     final Map<String, RegistryAuth> configs = parseDockerConfig(configPath).configs();
-    if (serverAddress != null && configs.containsKey(serverAddress)) {
-      return configs.get(serverAddress);
-    }
 
     if (isNullOrEmpty(serverAddress)) {
       if (configs.isEmpty()) {
@@ -86,6 +86,27 @@ private RegistryAuth parseDockerConfig(final Path configPath, final String serve
       return configs.values().iterator().next();
     }
 
+    if (configs.containsKey(serverAddress)) {
+      return configs.get(serverAddress);
+    }
+
+    // If the given server address didn't have a protocol try adding a protocol to the address.
+    // This handles cases where older versions of Docker included the protocol when writing
+    // auth tokens to config.json.
+    try {
+      final URI serverAddressUri = new URI(serverAddress);
+      if (serverAddressUri.getScheme() == null) {
+        for (String proto : Arrays.asList("https://", "http://")) {
+          final String addrWithProto = proto + serverAddress;
+          if (configs.containsKey(addrWithProto)) {
+            return configs.get(addrWithProto);
+          }
+        }
+      }
+    } catch (URISyntaxException e) {
+      // Nothing to do, just let this fall through below
+    }
+
     throw new IllegalArgumentException(
         "serverAddress=" + serverAddress + " does not appear in config file at " + configPath);
   }

src/test/java/com/spotify/docker/client/DockerConfigReaderTest.java

@@ -47,6 +47,7 @@
 import com.spotify.docker.client.messages.RegistryAuth;
 import com.spotify.docker.client.messages.RegistryConfigs;
 import java.io.FileNotFoundException;
+import java.io.IOException;
 import java.net.URL;
 import java.nio.file.Path;
 import java.nio.file.Paths;
@@ -160,6 +161,23 @@ public void testFromDockerConfig_MultiConfig() throws Exception {
     assertThat(dockerIoParsed, equalTo(DOCKER_AUTH_CONFIG));
   }
 
+  @Test
+  public void testFromDockerConfig_AddressProtocol() throws IOException {
+    final Path path = getTestFilePath("dockerConfig/protocolMissing.json");
+
+    // Server address matches exactly what's in the config file
+    final RegistryAuth noProto = reader.fromConfig(path, "docker.example.com");
+    assertThat(noProto.serverAddress(), equalTo("docker.example.com"));
+
+    // Server address doesn't have a protocol but the entry in the config file does (https)
+    final RegistryAuth httpsProto = reader.fromConfig(path, "repo.example.com");
+    assertThat(httpsProto.serverAddress(), equalTo("https://repo.example.com"));
+
+    // Server address doesn't have a protocol but the entry in the config file does (http)
+    final RegistryAuth httpProto = reader.fromConfig(path, "local.example.com");
+    assertThat(httpProto.serverAddress(), equalTo("http://local.example.com"));
+  }
+
   private static Path getTestFilePath(final String path) {
     if (OsUtils.isLinux() || OsUtils.isOsX()) {
       return getLinuxPath(path);

src/test/resources/dockerConfig/protocolMissing.json

@@ -0,0 +1,13 @@
+{
+  "auths": {
+    "docker.example.com": {
+      "auth": "ZG9ja2VybWFuOnN3NGd5MGxvCg=="
+    },
+    "https://repo.example.com": {
+      "auth": "ZG9ja2VybWFuOnN3NGd5MGxvCg=="
+    },
+    "http://local.example.com": {
+      "auth": "ZG9ja2VybWFuOnN3NGd5MGxvCg=="
+    }
+  }
+}