kbendick commented on a change in pull request #4184: URL: https://github.com/apache/iceberg/pull/4184#discussion_r814262754
########## File path: core/src/main/java/org/apache/iceberg/rest/responses/RESTCatalogConfigResponse.java ########## @@ -0,0 +1,154 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you under the Apache License, Version 2.0 (the + * "License"); you may not use this file except in compliance + * with the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, + * software distributed under the License is distributed on an + * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY + * KIND, either express or implied. See the License for the + * specific language governing permissions and limitations + * under the License. + */ + +package org.apache.iceberg.rest.responses; + +import java.util.Collections; +import java.util.Map; +import org.apache.iceberg.relocated.com.google.common.base.MoreObjects; +import org.apache.iceberg.relocated.com.google.common.base.Preconditions; +import org.apache.iceberg.relocated.com.google.common.collect.Maps; + +/** + * Represents a response to requesting server-side provided configuration for the REST catalog. + * This allows client provided values to be overridden by the server or defaulted if not provided by the client. + * <p> + * This configuration should be fetched with a one time initial HTTP request during the REST catalog initialization. + * The connection used to fetch the configuration should then be disposed and a new http client should be + * created for use with the catalog. + * <p> + * Configuration from the server consists of two sets of key/value pairs. + * <ul> + * <li> defaults - properties that should be used as default configuration </li> + * <li> overrides - properties that should be used to override client configuration </li> + * </ul> + */ +public class RESTCatalogConfigResponse { + + private Map<String, String> defaults; + private Map<String, String> overrides; + + public RESTCatalogConfigResponse() { + // Required for Jackson deserialization + } + + private RESTCatalogConfigResponse(Map<String, String> defaults, Map<String, String> overrides) { + this.defaults = defaults; + this.overrides = overrides; + validate(); + } + + RESTCatalogConfigResponse validate() { + return this; + } + + /** + * Properties that should be used as default configuration. {@code defaults} have the lowest priority + * and should be applied before the client provided configuration. + * + * @return properties that should be used as default configuration + */ + public Map<String, String> defaults() { + return defaults != null ? Maps.newHashMap(defaults) : Collections.emptyMap(); + } + + /** + * Properties that should be used to override client configuration. {@code overrides} have the highest priority + * and should be applied after defaults and any client-provided configuration properties. + * + * @return properties that should be given higher precedence than any client provided input + */ + public Map<String, String> overrides() { + return overrides != null ? Maps.newHashMap(overrides) : Collections.emptyMap(); + } + + /** + * Merge client-provided config with server side provided configuration to return a single + * properties map which will be used for instantiating and configuring the REST catalog. + * + * @param clientProperties - Client provided configuration + * @return Merged configuration, with precedence in the order overrides, then client properties, and then defaults. + */ + public Map<String, String> merge(Map<String, String> clientProperties) { + Preconditions.checkNotNull(clientProperties, + "Cannot merge client properties with server-provided properties. Invalid client configuration: null"); + Map<String, String> merged = Maps.newHashMap(defaults); + merged.putAll(clientProperties); + merged.putAll(overrides); + return merged; + } + + @Override + public String toString() { + return MoreObjects.toStringHelper(this) + .add("defaults", defaults) + .add("overrides", overrides) + .toString(); + } + + public static Builder builder() { + return new Builder(); + } + + public static class Builder { + private final Map<String, String> defaults; + private final Map<String, String> overrides; + + private Builder() { + this.defaults = Maps.newHashMap(); + this.overrides = Maps.newHashMap(); Review comment: Using immutable builders makes it so that a `null` value can't be set. Which people might want to do for `overrides` as one example to explicitly disable some configuration . For example, if an operator wanted to remove all client provided values for a given setting across all jobs for something temporarily, to maybe investigate too many connections to the catalog service or something. They could remove the clients configuration by placing `clients: null` into `overrides` and then setting `clients: 2` in their defaults. Somewhat of a contrived example, but at scale when operators and users are two separate groups, I think this could very much have a practical use case. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
