[
https://issues.apache.org/jira/browse/KNOX-940?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16008836#comment-16008836
]
Mohammad Kamrul Islam commented on KNOX-940:
--------------------------------------------
I need recommendations for the implementation.
Knox currently utilizes dropwizard to support metrics collection and reporting.
Dropwizard also supports framework to publish the metrics through REST , in
addition of other important endpoints.
Key part is to add
[AdminServlet|http://metrics.dropwizard.io/3.1.0/manual/servlets/#adminservlet]
into gateway service.
In addition, we need to add couple of ServletListeners.
My question is : What is the recommended way of adding new servlet in Knox? Any
example or details will make things easier for me.
I did a POC by creating the following diff and I accessed through these cURL
commands. This can show what we have to do ultimately. But I'm not sure : where
this code fits the best.
{quote}
curl -i -k https://localhost:8443/gateway/sandbox//metrics/metrics
curl -i -k https://localhost:8443/gateway/sandbox//metrics/ping
curl -i -k
https://localhost:8443/gateway/sandbox//metrics/healthcheck?pretty=true
{quote}
{quote}
diff --git a/gateway-server/pom.xml b/gateway-server/pom.xml
index 652e5f3b..755e3a0e 100644
--- a/gateway-server/pom.xml
+++ b/gateway-server/pom.xml
@@ -328,6 +328,11 @@
<artifactId>xmltool</artifactId>
<scope>test</scope>
</dependency>
+ <dependency>
+ <groupId>io.dropwizard.metrics</groupId>
+ <artifactId>metrics-servlets</artifactId>
+ <version>3.1.2</version>
+ </dependency>
</dependencies>
diff --git
a/gateway-server/src/main/java/org/apache/hadoop/gateway/deploy/DeploymentFactory.java
b/gateway-server/src/main/java/org/apache/hadoop/gateway/deploy/DeploymentFactory.java
index d834e740..07eaed69 100644
---
a/gateway-server/src/main/java/org/apache/hadoop/gateway/deploy/DeploymentFactory.java
+++
b/gateway-server/src/main/java/org/apache/hadoop/gateway/deploy/DeploymentFactory.java
@@ -37,6 +37,7 @@ import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Marshaller;
+import com.codahale.metrics.servlets.AdminServlet;
import org.apache.hadoop.gateway.GatewayMessages;
import org.apache.hadoop.gateway.GatewayServlet;
import org.apache.hadoop.gateway.config.GatewayConfig;
@@ -356,6 +357,10 @@ public abstract class DeploymentFactory {
wad.createFilter().filterName( filterName ).filterClass(
GatewayServlet.class.getName() );
wad.createFilterMapping().filterName( filterName ).urlPattern( "/*" );
}
+ String servletName = "metrics-admin";
+ System.out.println("registering AdminServlet");
+ wad.createServlet().servletName( servletName ).servletClass(
AdminServlet.class.getName() );
+ wad.createServletMapping().servletName( servletName ).urlPattern(
"/metrics/*" );
if (gatewayServices != null) {
gatewayServices.initializeContribution(context);
} else {
diff --git
a/gateway-server/src/main/java/org/apache/hadoop/gateway/services/DefaultGatewayServices.java
b/gateway-server/src/main/java/org/apache/hadoop/gateway/services/DefaultGatewayServices.java
index 2cf043eb..8cd672e5 100644
---
a/gateway-server/src/main/java/org/apache/hadoop/gateway/services/DefaultGatewayServices.java
+++
b/gateway-server/src/main/java/org/apache/hadoop/gateway/services/DefaultGatewayServices.java
@@ -218,6 +218,8 @@ public class DefaultGatewayServices implements
GatewayServices {
@Override
public void finalizeContribution(DeploymentContext context) {
// Tell the provider the location of the descriptor.
- context.getWebAppDescriptor().createListener().listenerClass(
GatewayServicesContextListener.class.getName() );
+
context.getWebAppDescriptor().createListener().listenerClass(GatewayServicesContextListener.class.getName());
+
context.getWebAppDescriptor().createListener().listenerClass(GatewayMetricsServletContextListener.class.getName());
+
context.getWebAppDescriptor().createListener().listenerClass(GatewayHealthCheckServletContextListener.class.getName());
}
}
diff --git
a/gateway-server/src/main/java/org/apache/hadoop/gateway/services/GatewayHealthCheckServletContextListener.java
b/gateway-server/src/main/java/org/apache/hadoop/gateway/services/GatewayHealthCheckServletContextListener.java
new file mode 100644
index 00000000..1b0f3ef5
--- /dev/null
+++
b/gateway-server/src/main/java/org/apache/hadoop/gateway/services/GatewayHealthCheckServletContextListener.java
@@ -0,0 +1,19 @@
+package org.apache.hadoop.gateway.services;
+
+import com.codahale.metrics.health.HealthCheckRegistry;
+import com.codahale.metrics.servlets.HealthCheckServlet;
+
+/**
+ * Created by mislam on 5/9/17.
+ */
+public class GatewayHealthCheckServletContextListener extends
HealthCheckServlet.ContextListener {
+
+ public static final HealthCheckRegistry HEALTH_CHECK_REGISTRY = new
HealthCheckRegistry();
+
+ @Override
+ protected HealthCheckRegistry getHealthCheckRegistry() {
+ System.out.println("GatewayHealthCheckServletContextListener CAlled");
+ return HEALTH_CHECK_REGISTRY;
+ }
+
+}
\ No newline at end of file
diff --git
a/gateway-server/src/main/java/org/apache/hadoop/gateway/services/GatewayMetricsServletContextListener.java
b/gateway-server/src/main/java/org/apache/hadoop/gateway/services/GatewayMetricsServletContextListener.java
new file mode 100644
index 00000000..334b0c4a
--- /dev/null
+++
b/gateway-server/src/main/java/org/apache/hadoop/gateway/services/GatewayMetricsServletContextListener.java
@@ -0,0 +1,15 @@
+package org.apache.hadoop.gateway.services;
+
+import com.codahale.metrics.MetricRegistry;
+import com.codahale.metrics.servlets.MetricsServlet;
+import org.apache.hadoop.gateway.services.metrics.impl.DefaultMetricsService;
+
+public class GatewayMetricsServletContextListener extends
MetricsServlet.ContextListener {
+
+ @Override
+ protected MetricRegistry getMetricRegistry() {
+ System.out.println("GatewayMetricsServletContextListener CAlled");
+ return DefaultMetricsService.metrics;
+ }
+
+}
diff --git
a/gateway-server/src/main/java/org/apache/hadoop/gateway/services/metrics/impl/DefaultMetricsService.java
b/gateway-server/src/main/java/org/apache/hadoop/gateway/services/metrics/impl/DefaultMetricsService.java
index 0fa8a44f..af08c209 100644
---
a/gateway-server/src/main/java/org/apache/hadoop/gateway/services/metrics/impl/DefaultMetricsService.java
+++
b/gateway-server/src/main/java/org/apache/hadoop/gateway/services/metrics/impl/DefaultMetricsService.java
@@ -38,7 +38,7 @@ import java.util.ServiceLoader;
public class DefaultMetricsService implements MetricsService {
private static GatewayMessages LOG = MessagesFactory.get(
GatewayMessages.class );
- private final MetricRegistry metrics = new MetricRegistry();
+ public static final MetricRegistry metrics = new MetricRegistry();
public static final String METRICS_REGISTRY = "metrics-registry";
{quote}
> Support REST access exposing metrics
> ------------------------------------
>
> Key: KNOX-940
> URL: https://issues.apache.org/jira/browse/KNOX-940
> Project: Apache Knox
> Issue Type: Task
> Reporter: Mohammad Kamrul Islam
> Assignee: Mohammad Kamrul Islam
>
> KNOX-643 added the support to publish metrics. However, the metrics are not
> accessible through REST. This JIRA is to add REST support.
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