From 65d444bb2f9a516cf94a4a172b5e5970fd0a5c2c Mon Sep 17 00:00:00 2001
From: Phil Winder <phil@winderresearch.com>
Date: Tue, 14 Mar 2017 15:56:34 +0000
Subject: [PATCH] Rationalise prometheus to produce RED metrics.

---
 pom.xml                                       | 18 ++++++-
 .../PrometheusAutoConfiguration.java          | 35 ++++++++++++++
 .../cart/configuration/WebMvcConfig.java      | 25 ++++++++++
 .../middleware/HTTPMonitoringInterceptor.java | 48 +++++++++++++++++++
 src/main/resources/application.properties     |  2 +
 5 files changed, 127 insertions(+), 1 deletion(-)
 create mode 100644 src/main/java/works/weave/socks/cart/configuration/PrometheusAutoConfiguration.java
 create mode 100644 src/main/java/works/weave/socks/cart/configuration/WebMvcConfig.java
 create mode 100644 src/main/java/works/weave/socks/cart/middleware/HTTPMonitoringInterceptor.java

diff --git a/pom.xml b/pom.xml
index e94b7a75d..eac7c9695 100644
--- a/pom.xml
+++ b/pom.xml
@@ -14,12 +14,13 @@
     <parent>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-starter-parent</artifactId>
-        <version>1.4.0.RELEASE</version>
+        <version>1.4.4.RELEASE</version>
     </parent>
 
     <properties>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
         <java.version>1.8</java.version>
+        <prometheus.version>0.0.21</prometheus.version>
     </properties>
 
     <dependencies>
@@ -36,6 +37,21 @@
             <artifactId>spring-cloud-starter-zipkin</artifactId>
             <version>1.1.0.RELEASE</version>
         </dependency>
+        <dependency>
+            <groupId>io.prometheus</groupId>
+            <artifactId>simpleclient_spring_boot</artifactId>
+            <version>${prometheus.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>io.prometheus</groupId>
+            <artifactId>simpleclient_hotspot</artifactId>
+            <version>${prometheus.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>io.prometheus</groupId>
+            <artifactId>simpleclient_servlet</artifactId>
+            <version>${prometheus.version}</version>
+        </dependency>
         <dependency>
             <groupId>org.springframework.data</groupId>
             <artifactId>spring-data-rest-hal-browser</artifactId>
diff --git a/src/main/java/works/weave/socks/cart/configuration/PrometheusAutoConfiguration.java b/src/main/java/works/weave/socks/cart/configuration/PrometheusAutoConfiguration.java
new file mode 100644
index 000000000..00420de9b
--- /dev/null
+++ b/src/main/java/works/weave/socks/cart/configuration/PrometheusAutoConfiguration.java
@@ -0,0 +1,35 @@
+package works.weave.socks.cart.configuration;
+
+import io.prometheus.client.exporter.MetricsServlet;
+import io.prometheus.client.hotspot.DefaultExports;
+import io.prometheus.client.spring.boot.SpringBootMetricsCollector;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.boot.actuate.endpoint.PublicMetrics;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
+import org.springframework.boot.web.servlet.ServletRegistrationBean;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+import java.util.Collection;
+
+@Configuration
+@ConditionalOnClass(SpringBootMetricsCollector.class)
+class PrometheusAutoConfiguration {
+    @Bean
+    @ConditionalOnMissingBean(SpringBootMetricsCollector.class)
+    SpringBootMetricsCollector springBootMetricsCollector(Collection<PublicMetrics> publicMetrics) {
+        SpringBootMetricsCollector springBootMetricsCollector = new SpringBootMetricsCollector
+                (publicMetrics);
+        springBootMetricsCollector.register();
+        return springBootMetricsCollector;
+    }
+
+    @Bean
+    @ConditionalOnMissingBean(name = "prometheusMetricsServletRegistrationBean")
+    ServletRegistrationBean prometheusMetricsServletRegistrationBean(@Value("${prometheus.metrics" +
+            ".path:/metrics}") String metricsPath) {
+        DefaultExports.initialize();
+        return new ServletRegistrationBean(new MetricsServlet(), metricsPath);
+    }
+}
diff --git a/src/main/java/works/weave/socks/cart/configuration/WebMvcConfig.java b/src/main/java/works/weave/socks/cart/configuration/WebMvcConfig.java
new file mode 100644
index 000000000..a6e7eded8
--- /dev/null
+++ b/src/main/java/works/weave/socks/cart/configuration/WebMvcConfig.java
@@ -0,0 +1,25 @@
+package works.weave.socks.cart.configuration;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
+import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;
+import works.weave.socks.cart.middleware.HTTPMonitoringInterceptor;
+
+@Configuration
+public class WebMvcConfig extends WebMvcConfigurerAdapter {
+    @Autowired
+    private HTTPMonitoringInterceptor httpMonitoringInterceptor;
+
+    @Bean
+    HTTPMonitoringInterceptor httpMonitoringInterceptor() {
+        return new HTTPMonitoringInterceptor();
+    }
+
+    @Override
+    public void addInterceptors(InterceptorRegistry registry) {
+        registry.addInterceptor(httpMonitoringInterceptor)
+                .addPathPatterns("/**");
+    }
+}
diff --git a/src/main/java/works/weave/socks/cart/middleware/HTTPMonitoringInterceptor.java b/src/main/java/works/weave/socks/cart/middleware/HTTPMonitoringInterceptor.java
new file mode 100644
index 000000000..36c68da44
--- /dev/null
+++ b/src/main/java/works/weave/socks/cart/middleware/HTTPMonitoringInterceptor.java
@@ -0,0 +1,48 @@
+package works.weave.socks.cart.middleware;
+
+import io.prometheus.client.Histogram;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.web.servlet.HandlerInterceptor;
+import org.springframework.web.servlet.ModelAndView;
+
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+public class HTTPMonitoringInterceptor implements HandlerInterceptor {
+    static final Histogram requestLatency = Histogram.build()
+            .name("request_duration_seconds")
+            .help("Request duration in seconds.")
+            .labelNames("service", "method", "route", "status_code")
+            .register();
+
+    private static final String startTimeKey = "startTime";
+
+    @Value("${spring.application.name:carts}")
+    private String serviceName;
+
+    @Override
+    public boolean preHandle(HttpServletRequest httpServletRequest, HttpServletResponse
+            httpServletResponse, Object o) throws Exception {
+        httpServletRequest.setAttribute(startTimeKey, System.nanoTime());
+        return true;
+    }
+
+    @Override
+    public void postHandle(HttpServletRequest httpServletRequest, HttpServletResponse
+            httpServletResponse, Object o, ModelAndView modelAndView) throws Exception {
+        long start = (long) httpServletRequest.getAttribute(startTimeKey);
+        long elapsed = System.nanoTime() - start;
+        double seconds = (double) elapsed / 1000000000.0;
+        requestLatency.labels(
+                serviceName,
+                httpServletRequest.getMethod(),
+                httpServletRequest.getServletPath(),
+                Integer.toString(httpServletResponse.getStatus())
+        ).observe(seconds);
+    }
+
+    @Override
+    public void afterCompletion(HttpServletRequest httpServletRequest, HttpServletResponse
+            httpServletResponse, Object o, Exception e) throws Exception {
+    }
+}
diff --git a/src/main/resources/application.properties b/src/main/resources/application.properties
index 35146f238..855a29ee6 100644
--- a/src/main/resources/application.properties
+++ b/src/main/resources/application.properties
@@ -4,3 +4,5 @@ endpoints.health.enabled=false
 spring.zipkin.baseUrl=http://${zipkin:zipkin}:9411/
 spring.sleuth.sampler.percentage=1.0
 spring.application.name=carts
+# Disable actuator metrics endpoints
+endpoints.metrics.enabled=false