Topic enforcer to generate Strimzi KafkaTopic resources.

kafka_topic_enforcer/README.md

@@ -9,6 +9,8 @@ Kafka topic enforcer's goal is to automate Kafka topic management & hence remove
 * Self service, removed dependency on a human
 * Simple configuration
 
+If you choose to use Strimzi Kafka operator, this command can also generate Strimzi KafkaTopic CRDs.
+
 ## Dependencies
 
 * JVM 
@@ -51,6 +53,9 @@ Usage: <main class> [options] [command] [command options]
     enforce      Enforce given configuration
       Usage: enforce [options] path to a configuration file
         Options:
+          --cluster
+            a cluster name, if specified, consolidated (multi-cluster)
+            configuration file is expected
           --continuous, -c
             run enforcement continuously
             Default: false
@@ -63,6 +68,16 @@ Usage: <main class> [options] [command] [command options]
           --unsafemode
             run in unsafe mode, topic deletion is _only_ allowed in this mode
             Default: false
+    strimzi      Generate the Strimzi KafkaTopic resources YAML on stdout from
+            the topic config. Certain information such as topic tags and
+            config comments would be missed.
+      Usage: strimzi [options] /path/to/a/configuration/file
+        Options:
+          --cluster
+            a cluster name, if specified, consolidated (multi-cluster)
+            configuration file is expected
+        * --kafka_name, -k
+            the name of the Strimzi Kafka cluster to be generated for
 ```
 
 ## Configuration

kafka_topic_enforcer/src/main/java/com/tesla/data/topic/enforcer/BUILD

@@ -10,8 +10,13 @@ java_library(
         "//3rdparty/jvm/com/fasterxml/jackson/core:jackson_databind",
         "//3rdparty/jvm/com/fasterxml/jackson/dataformat:jackson_dataformat_yaml",
         "//3rdparty/jvm/com/fasterxml/jackson/module:jackson_module_parameter_names",
+        "//3rdparty/jvm/com/google/guava",
+        "//3rdparty/jvm/io/fabric8:kubernetes_client_api",
+        "//3rdparty/jvm/io/fabric8:kubernetes_model_common",
+        "//3rdparty/jvm/io/fabric8:kubernetes_model_core",
         "//3rdparty/jvm/io/prometheus:simpleclient",
         "//3rdparty/jvm/io/prometheus:simpleclient_httpserver",
+        "//3rdparty/jvm/io/strimzi:api",
         "//3rdparty/jvm/org/apache/kafka:kafka_clients",
         "//3rdparty/jvm/org/slf4j:slf4j_api",
         "//3rdparty/jvm_shaded/com/google/guava_shaded",

kafka_topic_enforcer/src/main/java/com/tesla/data/topic/enforcer/Main.java

@@ -48,6 +48,7 @@ public static void main(String[] args) {
     final Main main = new Main();
     final Map<String, BaseCommand<ConfiguredTopic>> commands = new HashMap<>();
     commands.put("validate", new BaseCommand<>());
+    commands.put("strimzi", new StrimziCommand());
     commands.put("dump", new DumpCommand());
     commands.put("enforce", new TopicEnforceCommand());
 

kafka_topic_enforcer/src/main/java/com/tesla/data/topic/enforcer/StrimziCommand.java

@@ -0,0 +1,95 @@
+/*
+ * Copyright (C) 2024 Tesla Motors, Inc. All rights reserved.
+ */
+
+package com.tesla.data.topic.enforcer;
+
+import com.tesla.data.enforcer.BaseCommand;
+
+import com.beust.jcommander.Parameter;
+import com.beust.jcommander.Parameters;
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.dataformat.yaml.YAMLFactory;
+import com.fasterxml.jackson.dataformat.yaml.YAMLGenerator;
+import com.google.common.base.CaseFormat;
+import com.google.common.hash.Hashing;
+import io.strimzi.api.kafka.model.topic.KafkaTopic;
+import io.strimzi.api.kafka.model.topic.KafkaTopicBuilder;
+
+import java.nio.charset.StandardCharsets;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+@Parameters(commandDescription = "Generate the Strimzi KafkaTopic resources YAML on stdout from the topic config. " +
+    "Certain information such as topic tags and config comments would be missed.")
+public class StrimziCommand extends BaseCommand<ConfiguredTopic> {
+
+  @Parameter(
+      names = {"--kafka_name", "-k"},
+      description = "the name of the Strimzi Kafka cluster to be generated for",
+      required = true)
+  protected String kafkaName;
+
+  @Override
+  public int run() {
+    List<ConfiguredTopic> configuredTopics = configuredEntities(ConfiguredTopic.class, "topics", "topicsFile");
+
+    ObjectMapper yamlMapper = new ObjectMapper(new YAMLFactory()
+        .configure(YAMLGenerator.Feature.WRITE_DOC_START_MARKER, true)
+        .configure(YAMLGenerator.Feature.LITERAL_BLOCK_STYLE, true)
+        .configure(YAMLGenerator.Feature.MINIMIZE_QUOTES, true)
+        .configure(YAMLGenerator.Feature.INDENT_ARRAYS, false)
+        .configure(YAMLGenerator.Feature.SPLIT_LINES, false)
+    );
+
+    try {
+      for (ConfiguredTopic topic : configuredTopics) {
+        System.out.println(yamlMapper.writeValueAsString(getKafkaTopic(topic)));
+      }
+    } catch (JsonProcessingException e) {
+      LOG.error("Failed to dump config", e);
+      return FAILURE;
+    }
+
+    return SUCCESS;
+  }
+
+  /**
+   * Takes the best effort to convert the topic names to a resource name compatible format. We are not aiming at perfect
+   * correctness for mixed cases. Instead, we take some heuristics to get some good enough results.
+   */
+  private String toResourceName(String s) {
+    // If the topic name contains an underscore, we assume it follows underscore case.
+    if (s.contains("_")) {
+      return CaseFormat.LOWER_UNDERSCORE.to(CaseFormat.LOWER_HYPHEN, s.toLowerCase()).replaceAll("[^-.a-z0-9]","");
+    }
+    // We assume the original name is upper camel case and take the best effort, even if it's not.
+    return CaseFormat.UPPER_CAMEL.to(CaseFormat.LOWER_HYPHEN, s).replaceAll("[^-.a-z0-9]","");
+  }
+
+  private KafkaTopic getKafkaTopic(ConfiguredTopic enforcerTopic) {
+    // Kubernetes resources follow RFC 1123 naming convention, so we have to remove the unsupported characters. To avoid
+    // duplications, we are appending a short hash string of the original topic name.
+    String topicHash = Hashing.sha256().hashString(enforcerTopic.getName(), StandardCharsets.UTF_8)
+        .toString().substring(0, 6);
+    // There could be some Kafka topics under the same names but for different Kafka clusters. To avoid ambiguity,
+    // we prepend the Kafka cluster names in the KafkaTopic metadata name.
+    String resourceName = kafkaName + "." + toResourceName(enforcerTopic.getName()) + "-" + topicHash;
+
+    return new KafkaTopicBuilder()
+        .withNewMetadata()
+          .withName(resourceName)
+          .withLabels(Map.of("strimzi.io/cluster", kafkaName))
+        .endMetadata()
+        .withNewSpec()
+          .withTopicName(enforcerTopic.getName())
+          .withPartitions(enforcerTopic.getPartitions())
+          .withReplicas((int) enforcerTopic.getReplicationFactor())
+          .withConfig(new HashMap<>(enforcerTopic.getConfig()))
+        .endSpec().build();
+  }
+}
+
+