Add a quick and dirty 'docker context' reader implementation

engine/src/main/java/de/gesellix/docker/authentication/AuthConfigReader.java

@@ -1,14 +1,11 @@
 package de.gesellix.docker.authentication;
 
-import com.squareup.moshi.Moshi;
+import de.gesellix.docker.engine.DockerConfigReader;
 import de.gesellix.docker.engine.DockerEnv;
-import okio.Okio;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 import java.io.File;
-import java.text.MessageFormat;
-import java.util.Collections;
 import java.util.Map;
 
 import static de.gesellix.docker.authentication.AuthConfig.EMPTY_AUTH_CONFIG;
@@ -17,21 +14,21 @@ public class AuthConfigReader {
 
   private final static Logger log = LoggerFactory.getLogger(AuthConfigReader.class);
 
-  private final Moshi moshi = new Moshi.Builder().build();
-
   private final DockerEnv env;
+  private DockerConfigReader dockerConfigReader;
 
   public AuthConfigReader() {
     this(new DockerEnv());
   }
 
   public AuthConfigReader(DockerEnv env) {
     this.env = env;
+    this.dockerConfigReader = env.getDockerConfigReader();
   }
 
   //  @Override
   public AuthConfig readDefaultAuthConfig() {
-    return readAuthConfig(null, env.getDockerConfigFile());
+    return readAuthConfig(null, dockerConfigReader.getDockerConfigFile());
   }
 
   //  @Override
@@ -42,7 +39,7 @@ public AuthConfig readAuthConfig(String hostname, File dockerCfg) {
       hostname = env.getIndexUrl_v1();
     }
 
-    Map parsedDockerCfg = readDockerConfigFile(dockerCfg);
+    Map parsedDockerCfg = dockerConfigReader.readDockerConfigFile(dockerCfg);
     if (parsedDockerCfg == null || parsedDockerCfg.isEmpty()) {
       return EMPTY_AUTH_CONFIG;
     }
@@ -51,24 +48,6 @@ public AuthConfig readAuthConfig(String hostname, File dockerCfg) {
     return credsStore.getAuthConfig(hostname);
   }
 
-  public Map readDockerConfigFile(File dockerCfg) {
-    if (dockerCfg == null) {
-      dockerCfg = env.getDockerConfigFile();
-    }
-    if (dockerCfg == null || !dockerCfg.exists()) {
-      log.info("docker config '${dockerCfg}' doesn't exist");
-      return Collections.emptyMap();
-    }
-    log.debug("reading auth info from {}", dockerCfg);
-    try {
-      return moshi.adapter(Map.class).fromJson(Okio.buffer(Okio.source(dockerCfg)));
-    }
-    catch (Exception e) {
-      log.debug(MessageFormat.format("failed to read auth info from {}", dockerCfg), e);
-      return Collections.emptyMap();
-    }
-  }
-
   public CredsStore getCredentialsStore(Map parsedDockerCfg) {
     return getCredentialsStore(parsedDockerCfg, "");
   }

engine/src/main/java/de/gesellix/docker/context/ContextStore.java

@@ -0,0 +1,32 @@
+package de.gesellix.docker.context;
+
+import de.gesellix.docker.engine.DockerEnv;
+
+import java.io.File;
+import java.util.Objects;
+
+public class ContextStore {
+
+  private final MetadataStore metadataStore;
+
+  public ContextStore(File dockerContextStoreDir) {
+    File metaRoot = new File(dockerContextStoreDir, MetadataStore.metadataDir);
+//    final String tlsDir = "tls";
+//    File tlsRoot = new File(env.getDockerContextStoreDir(), tlsDir);
+    metadataStore = new MetadataStore(metaRoot);
+  }
+
+  public Metadata getMetadata(String contextName) {
+    if (Objects.equals(contextName, DockerEnv.dockerDefaultContextName)) {
+      // should return the equivalent metadata of `docker context inspect default`
+      Metadata metadata = new Metadata(DockerEnv.dockerDefaultContextName);
+      metadata.setMetadata(new DockerContext(""));
+      metadata.getEndpoints().put(
+          DockerEnv.dockerEndpointDefaultName,
+          new EndpointMetaBase(DockerEnv.getDockerHostFromSystemPropertyOrEnvironment(), false));
+      return metadata;
+    }
+
+    return metadataStore.getMetadata(contextName);
+  }
+}

engine/src/main/java/de/gesellix/docker/context/DockerContext.java

@@ -0,0 +1,14 @@
+package de.gesellix.docker.context;
+
+import java.util.Map;
+
+public class DockerContext {
+  String description;
+
+  // e.g. `"StackOrchestrator": "swarm"`
+  Map<String, Object> additionalFields;
+
+  public DockerContext(String description) {
+    this.description = description;
+  }
+}

engine/src/main/java/de/gesellix/docker/context/DockerContextResolver.java

@@ -0,0 +1,48 @@
+package de.gesellix.docker.context;
+
+import de.gesellix.docker.engine.DockerConfigReader;
+import de.gesellix.docker.engine.DockerEnv;
+
+import java.util.Map;
+
+public class DockerContextResolver {
+
+  // see the original implementation at https://github.com/docker/cli/blob/de6020a240ff95c97150f07d7a0dd59981143868/cli/command/cli.go#L448
+  public String resolveDockerContextName(DockerConfigReader dockerConfigReader) {
+    String dockerHost = DockerEnv.getDockerHostFromSystemPropertyOrEnvironment();
+    String dockerContext = DockerEnv.getDockerContextFromSystemPropertyOrEnvironment();
+//    if (dockerContext != null && dockerHost != null) {
+//      throw new IllegalStateException("Conflicting options: either specify --host or --context, not both");
+//    }
+    if (dockerContext != null) {
+      return dockerContext;
+    }
+    if (dockerHost != null) {
+      return DockerEnv.dockerDefaultContextName;
+    }
+    Map<String, Object> configFile = dockerConfigReader.readDockerConfigFile();
+    if (configFile != null && configFile.containsKey("currentContext")) {
+      // TODO ensure `currentContext` to be valid
+      // _, err := contextstore.GetMetadata(config.CurrentContext)
+      // if errdefs.IsNotFound(err) {
+      //   return "", errors.Errorf("current context %q is not found on the file system, please check your config file at %s", config.CurrentContext, config.Filename)
+      // }
+      return (String) configFile.get("currentContext");
+    }
+    return DockerEnv.dockerDefaultContextName;
+  }
+
+  // see the original implementation at https://github.com/docker/cli/blob/de6020a240ff95c97150f07d7a0dd59981143868/cli/command/cli.go#L278
+  public EndpointMetaBase resolveDockerEndpoint(ContextStore store, String contextName) {
+    Metadata metadata = store.getMetadata(contextName);
+    if (metadata == null || metadata.getEndpoints() == null || !metadata.getEndpoints().containsKey(DockerEnv.dockerEndpointDefaultName)) {
+      throw new IllegalStateException("cannot find docker endpoint in context " + contextName);
+    }
+    if (!(metadata.getEndpoints().get(DockerEnv.dockerEndpointDefaultName) instanceof EndpointMetaBase)) {
+      throw new IllegalStateException("endpoint " + DockerEnv.dockerEndpointDefaultName + " is not of type EndpointMetaBase");
+//      throw new IllegalStateException("endpoint " + DockerEnv.dockerEndpointDefaultName + " is not of type EndpointMeta");
+    }
+    // TODO TLSData
+    return (EndpointMetaBase) metadata.getEndpoints().get(DockerEnv.dockerEndpointDefaultName);
+  }
+}

engine/src/main/java/de/gesellix/docker/context/EndpointMetaBase.java

@@ -0,0 +1,34 @@
+package de.gesellix.docker.context;
+
+import java.util.Objects;
+
+public class EndpointMetaBase {
+  private String host;
+  private Boolean skipTLSVerify;
+
+  public EndpointMetaBase(String host, Boolean skipTLSVerify) {
+    this.host = host;
+    this.skipTLSVerify = skipTLSVerify;
+  }
+
+  public String getHost() {
+    return host;
+  }
+
+  public Boolean getSkipTLSVerify() {
+    return skipTLSVerify;
+  }
+
+  @Override
+  public boolean equals(Object o) {
+    if (this == o) return true;
+    if (o == null || getClass() != o.getClass()) return false;
+    EndpointMetaBase that = (EndpointMetaBase) o;
+    return Objects.equals(getHost(), that.getHost()) && Objects.equals(getSkipTLSVerify(), that.getSkipTLSVerify());
+  }
+
+  @Override
+  public int hashCode() {
+    return Objects.hash(getHost(), getSkipTLSVerify());
+  }
+}

engine/src/main/java/de/gesellix/docker/context/Metadata.java

@@ -0,0 +1,32 @@
+package de.gesellix.docker.context;
+
+import java.util.HashMap;
+import java.util.Map;
+
+public class Metadata {
+  private String name;
+
+  private Object metadata;
+
+  private Map<String, Object> endpoints = new HashMap<>();
+
+  public Metadata(String name) {
+    this.name = name;
+  }
+
+  public String getName() {
+    return name;
+  }
+
+  public Object getMetadata() {
+    return metadata;
+  }
+
+  public void setMetadata(Object metadata) {
+    this.metadata = metadata;
+  }
+
+  public Map<String, Object> getEndpoints() {
+    return endpoints;
+  }
+}

engine/src/main/java/de/gesellix/docker/context/MetadataStore.java

@@ -0,0 +1,84 @@
+package de.gesellix.docker.context;
+
+import com.squareup.moshi.Moshi;
+import de.gesellix.docker.engine.DockerEnv;
+import okio.Okio;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.math.BigInteger;
+import java.nio.charset.StandardCharsets;
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+import java.text.MessageFormat;
+import java.util.Collections;
+import java.util.Map;
+
+public class MetadataStore {
+  private final static Logger log = LoggerFactory.getLogger(MetadataStore.class);
+
+  public final static String metadataDir = "meta";
+  final String metaFile = "meta.json";
+
+  private final Moshi moshi = new Moshi.Builder().build();
+
+  File root;
+//  Config config;
+
+  public MetadataStore(File root) {
+    this.root = root;
+  }
+
+  public Metadata getMetadata(String contextName) {
+    return getByID(getContextDir(contextName));
+  }
+
+  public Metadata getByID(String contextDirectory) {
+    Map payload = getMetadataPayload(contextDirectory);
+    Metadata metadata = new Metadata((String) payload.get("Name"));
+    // TODO `metadata` should be read type safe
+    // see https://github.com/docker/cli/blob/09c94c1c21cb2ed02d347934de85b6163dc62ddf/cli/context/store/metadatastore.go#L83
+    metadata.setMetadata(payload.get("Metadata"));
+    // TODO each `endpoint` should be read type safe
+    // see https://github.com/docker/cli/blob/09c94c1c21cb2ed02d347934de85b6163dc62ddf/cli/context/store/metadatastore.go#L87
+    metadata.getEndpoints().putAll((Map<String, Object>) payload.get("Endpoints"));
+    if (metadata.getEndpoints().containsKey(DockerEnv.dockerEndpointDefaultName)) {
+      Map<String, Object> endpointMeta = (Map<String, Object>) metadata.getEndpoints().get(DockerEnv.dockerEndpointDefaultName);
+      metadata.getEndpoints().put(
+          DockerEnv.dockerEndpointDefaultName,
+          new EndpointMetaBase((String) endpointMeta.get("Host"), false));
+    }
+    return metadata;
+  }
+
+  // Code taken from https://stackoverflow.com/a/62401723/372019
+  // SHA256 ist the current implementation in the docker/cli,
+  // see https://github.com/docker/cli/blob/cd7c493ea2cfb8c6db0beb65cf9830c8df23a9f9/cli/context/store/store.go#L8
+  public String getContextDir(String contextName) {
+    MessageDigest messageDigest;
+    try {
+      messageDigest = MessageDigest.getInstance("SHA-256");
+    } catch (NoSuchAlgorithmException e) {
+      throw new RuntimeException(e);
+    }
+    byte[] hashBytes = messageDigest.digest(contextName.getBytes(StandardCharsets.UTF_8));
+    BigInteger noHash = new BigInteger(1, hashBytes);
+    String hashStr = noHash.toString(16);
+    return hashStr;
+  }
+
+  private Map getMetadataPayload(String contextDirectory) {
+    File contextMetadata = new File(new File(root, contextDirectory), metaFile);
+    if (!contextMetadata.exists()) {
+      throw new IllegalStateException("context does not exist", new FileNotFoundException(contextMetadata.getAbsolutePath()));
+    }
+    try {
+      return moshi.adapter(Map.class).fromJson(Okio.buffer(Okio.source(contextMetadata)));
+    } catch (Exception e) {
+      log.debug(MessageFormat.format("failed to read metadata from {}", contextMetadata), e);
+      return Collections.emptyMap();
+    }
+  }
+}