feature(ui): service/cluster information and status page

.gitignore

@@ -31,6 +31,7 @@ docs/book
 docs/mdbook
 
 hs_err*.log
+replay_pid*.log
 /data/
 /metrics/
-docker/**/*.jar
+docker/**/*.jar

CONTRIBUTING.md

@@ -100,3 +100,34 @@ type ```text``` in PostgreSQL. This type needs some special treatment.
 you will see just some 5-digit numbers.\
 **Solution**: you need to convert the large object like this\
 ```SELECT convert_from(lo_get(value_::oid), 'UTF8') FROM variable```
+
+### Known Issue: Application Failed To Start, required bean 'BuildProperties' could not be found 
+
+If you're about to run the application locally (e.g. via IntelliJ 'run'),
+you might run into the issue
+
+```
+***************************
+APPLICATION FAILED TO START
+***************************
+
+Description:
+
+Field buildProperties in io.zeebe.monitor.rest.ServiceStatusViewController required a bean of type 'org.springframework.boot.info.BuildProperties' that could not be found.
+```
+
+#### Solution
+
+Simply compile the application via maven command.
+```shell
+mvn -DskipTests compile
+```
+
+#### Root cause
+
+The Spring framework supports injecting build information at runtime.
+This requires a file ```META-INF/build-info.properties``` to be present in the classpath.
+This file is created by Maven during the compile phase, via ```spring-boot-maven-plugin``` (see pom.xml).
+When using e.g. IntelliJ 'run' command, Maven is not used by default, to build the application,
+and thus, the file is missing and the bean can't be created.
+The error message is completely miss-leading.

pom.xml

@@ -236,7 +236,14 @@
             <plugin>
                 <groupId>org.springframework.boot</groupId>
                 <artifactId>spring-boot-maven-plugin</artifactId>
+                <version>2.5.2</version>
                 <executions>
+                    <execution>
+                        <id>build-info</id>
+                        <goals>
+                            <goal>build-info</goal>
+                        </goals>
+                    </execution>
                     <execution>
                         <goals>
                             <goal>repackage</goal>

src/main/java/io/zeebe/monitor/ZeebeSimpleMonitorApp.java

@@ -36,6 +36,8 @@
 @EnableSpringDataWebSupport
 public class ZeebeSimpleMonitorApp {
 
+  public static final String REPLACEMENT_CHARACTER_QUESTIONMARK = "\u2370"; // == ⍰ character
+
   public static void main(final String... args) {
     SpringApplication.run(ZeebeSimpleMonitorApp.class, args);
   }
@@ -58,6 +60,9 @@ public Executor asyncExecutor() {
   @Bean
   public Mustache.Compiler configureFallbackValueForMissingVariablesInMustacheTemplates(
       Mustache.TemplateLoader templateLoader) {
-    return Mustache.compiler().defaultValue("⍰").withLoader(templateLoader);
+    return Mustache.compiler()
+        .defaultValue(REPLACEMENT_CHARACTER_QUESTIONMARK)
+        .withLoader(templateLoader);
   }
+
 }

src/main/java/io/zeebe/monitor/rest/ServiceStatusViewController.java

@@ -0,0 +1,62 @@
+package io.zeebe.monitor.rest;
+
+import io.camunda.zeebe.client.api.response.BrokerInfo;
+import io.camunda.zeebe.client.api.response.PartitionInfo;
+import io.camunda.zeebe.client.api.response.Topology;
+import io.zeebe.monitor.rest.dto.BrokerDto;
+import io.zeebe.monitor.rest.dto.PartitionInfoDto;
+import io.zeebe.monitor.rest.dto.StatusDto;
+import io.zeebe.monitor.zeebe.ZeebeStatusService;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.info.BuildProperties;
+import org.springframework.data.domain.Pageable;
+import org.springframework.stereotype.Controller;
+import org.springframework.web.bind.annotation.GetMapping;
+
+import java.util.Map;
+
+@Controller
+public class ServiceStatusViewController extends AbstractViewController {
+
+  @Autowired private ZeebeStatusService zeebeStatusService;
+  @Autowired BuildProperties buildProperties;
+
+  @GetMapping("/views/service-status")
+  public String index(final Map<String, Object> model, final Pageable pageable) {
+    addDefaultAttributesToModel(model);
+
+    final Topology topology = zeebeStatusService.getTopology();
+    model.put("status", toDto(topology, buildProperties));
+
+    return "service-status-view";
+  }
+
+  private StatusDto toDto(Topology topology, BuildProperties buildProperties) {
+    final StatusDto statusDto = new StatusDto();
+    statusDto.setClusterSize(topology.getClusterSize());
+    statusDto.setGatewayVersion(topology.getGatewayVersion());
+    statusDto.setPartitionsCount(topology.getPartitionsCount());
+    statusDto.setReplicationFactor(topology.getReplicationFactor());
+    statusDto.setSimpleMonitorVersion(buildProperties.getVersion());
+    statusDto.setSimpleMonitorBuildTime(buildProperties.getTime().toString());
+    for (BrokerInfo broker : topology.getBrokers()) {
+      final BrokerDto brokerDto = new BrokerDto();
+      brokerDto.setAddress(broker.getAddress());
+      brokerDto.setHost(broker.getHost());
+      brokerDto.setNodeId(broker.getNodeId());
+      brokerDto.setPort(broker.getPort());
+      brokerDto.setVersion(broker.getVersion());
+      for (PartitionInfo partition : broker.getPartitions()) {
+        final PartitionInfoDto partitionInfoDto = new PartitionInfoDto();
+        partitionInfoDto.setPartitionId(partition.getPartitionId());
+        partitionInfoDto.setRole(String.valueOf(partition.getRole()));
+        partitionInfoDto.setHealth(String.valueOf(partition.getHealth()));
+        partitionInfoDto.setLeader(partition.isLeader());
+        brokerDto.addPartitionInfo(partitionInfoDto);
+      }
+      statusDto.addBroker(brokerDto);
+    }
+    return statusDto;
+  }
+
+}

src/main/java/io/zeebe/monitor/rest/dto/BrokerDto.java

@@ -0,0 +1,61 @@
+package io.zeebe.monitor.rest.dto;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class BrokerDto {
+  private int nodeId;
+  private String address;
+  private String host;
+  private int port;
+  private String version;
+  private List<PartitionInfoDto> partitionInfos = new ArrayList<>();
+
+  public void setAddress(String address) {
+    this.address = address;
+  }
+
+  public String getAddress() {
+    return address;
+  }
+
+  public void setHost(String host) {
+    this.host = host;
+  }
+
+  public String getHost() {
+    return host;
+  }
+
+  public void setNodeId(int nodeId) {
+    this.nodeId = nodeId;
+  }
+
+  public int getNodeId() {
+    return nodeId;
+  }
+
+  public void setPort(int port) {
+    this.port = port;
+  }
+
+  public int getPort() {
+    return port;
+  }
+
+  public void setVersion(String version) {
+    this.version = version;
+  }
+
+  public String getVersion() {
+    return version;
+  }
+
+  public void addPartitionInfo(PartitionInfoDto partitionInfoDto) {
+    this.partitionInfos.add(partitionInfoDto);
+  }
+
+  public List<PartitionInfoDto> getPartitionInfos() {
+    return partitionInfos;
+  }
+}

src/main/java/io/zeebe/monitor/rest/dto/PartitionInfoDto.java

@@ -0,0 +1,41 @@
+package io.zeebe.monitor.rest.dto;
+
+public class PartitionInfoDto {
+
+  private int partitionId;
+  private String role;
+  private String health;
+  private boolean leader;
+
+  public void setPartitionId(int partitionId) {
+    this.partitionId = partitionId;
+  }
+
+  public int getPartitionId() {
+    return partitionId;
+  }
+
+  public void setRole(String role) {
+    this.role = role;
+  }
+
+  public String getRole() {
+    return role;
+  }
+
+  public void setHealth(String health) {
+    this.health = health;
+  }
+
+  public String getHealth() {
+    return health;
+  }
+
+  public void setLeader(boolean leader) {
+    this.leader = leader;
+  }
+
+  public boolean getLeader() {
+    return leader;
+  }
+}

src/main/java/io/zeebe/monitor/rest/dto/StatusDto.java

@@ -0,0 +1,71 @@
+package io.zeebe.monitor.rest.dto;
+
+import java.time.Instant;
+import java.util.ArrayList;
+import java.util.List;
+
+public class StatusDto {
+  private String gatewayVersion;
+  private String simpleMonitorVersion;
+  private int clusterSize;
+  private int replicationFactor;
+  private int partitionsCount;
+  private List<BrokerDto> brokers = new ArrayList<>();
+  private String simpleMonitorBuildTime;
+
+  public void setClusterSize(int clusterSize) {
+    this.clusterSize = clusterSize;
+  }
+
+  public int getClusterSize() {
+    return clusterSize;
+  }
+
+  public void setGatewayVersion(String gatewayVersion) {
+    this.gatewayVersion = gatewayVersion;
+  }
+
+  public String getGatewayVersion() {
+    return gatewayVersion;
+  }
+
+  public void setReplicationFactor(int replicationFactor) {
+    this.replicationFactor = replicationFactor;
+  }
+
+  public int getReplicationFactor() {
+    return replicationFactor;
+  }
+
+  public void setPartitionsCount(int partitionsCount) {
+    this.partitionsCount = partitionsCount;
+  }
+
+  public int getPartitionsCount() {
+    return partitionsCount;
+  }
+
+  public void addBroker(BrokerDto brokerDto) {
+    this.brokers.add(brokerDto);
+  }
+
+  public List<BrokerDto> getBrokers() {
+    return brokers;
+  }
+
+  public void setSimpleMonitorVersion(String simpleMonitorVersion) {
+    this.simpleMonitorVersion = simpleMonitorVersion;
+  }
+
+  public String getSimpleMonitorVersion() {
+    return simpleMonitorVersion;
+  }
+
+  public void setSimpleMonitorBuildTime(String simpleMonitorBuildTime) {
+    this.simpleMonitorBuildTime = simpleMonitorBuildTime;
+  }
+
+  public String getSimpleMonitorBuildTime() {
+    return simpleMonitorBuildTime;
+  }
+}

src/main/java/io/zeebe/monitor/zeebe/ZeebeStatusService.java

@@ -0,0 +1,23 @@
+package io.zeebe.monitor.zeebe;
+
+import io.camunda.zeebe.client.ZeebeClient;
+import io.camunda.zeebe.client.api.response.Topology;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Component;
+
+import java.time.Duration;
+
+@Component
+public class ZeebeStatusService {
+
+  @Autowired private ZeebeClient zeebeClient;
+
+  public Topology getTopology() {
+    return zeebeClient.newTopologyRequest()
+        .requestTimeout(Duration.ofSeconds(5))
+        .send()
+        .join();
+  }
+
+
+}