feat: Allow custom prometheus info metric (#83)

#### Motivation
Allow the generation of an "info" metric by way of environment variables captured as `Gauge` metric set up during container startup

#### Modifications
- Added environment variable `MMESH_CUSTOM_ENV_VAR` in `ModelMeshEnvVars`
- Added map `infoMetricParams` and logic to parse and pass the info to prometheus in `ModelMesh`
- Added a `Gauge` using the parsed label names and values in `Metrics`
- Added sample variables to `pom.xml` for testing and related test in `ModelMeshMetricsTest`

#### Result
- Support to pass information by via environment variables parsed as `<metricname>[;label1=envVarWithValueforLabel1,label2=envVarWithValueforLabel2,...,labelN=envVarWithValueforLabelN,]` if provided.



Signed-off-by: Rafael Vasquez <raf.vasquez@ibm.com>

pom.xml

@@ -164,6 +164,13 @@
           </argLine>
           <!-- required to workaround issue with openjdk 8u181-b13-2 -->
           <useSystemClassLoader>false</useSystemClassLoader>
+          <environmentVariables>
+            <MM_INFO_METRICS>assistant_deployment_info:relabel;deployment=DEPLOYMENT_NAME,slot=SLOT_NAME,component=COMPONENT_NAME,group=GROUP_NAME</MM_INFO_METRICS>
+            <DEPLOYMENT_NAME>ga-tf-mm</DEPLOYMENT_NAME>
+            <SLOT_NAME>ga</SLOT_NAME>
+            <COMPONENT_NAME>tf-mm</COMPONENT_NAME>
+            <GROUP_NAME>clu</GROUP_NAME>
+          </environmentVariables>
         </configuration>
       </plugin>
 

src/main/java/com/ibm/watson/modelmesh/Metrics.java

@@ -36,21 +36,20 @@
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 
+import java.lang.reflect.Array;
 import java.net.SocketAddress;
 import java.nio.channels.DatagramChannel;
-import java.util.Collections;
-import java.util.EnumMap;
-import java.util.HashMap;
-import java.util.HashSet;
-import java.util.Map;
+import java.util.*;
 import java.util.Map.Entry;
-import java.util.Set;
 import java.util.concurrent.Callable;
 import java.util.concurrent.LinkedBlockingQueue;
 import java.util.concurrent.TimeUnit;
+import java.util.stream.Stream;
 
 import static com.ibm.watson.modelmesh.Metric.*;
 import static com.ibm.watson.modelmesh.ModelMesh.M;
+import static com.ibm.watson.modelmesh.ModelMeshEnvVars.MMESH_CUSTOM_ENV_VAR;
+import static com.ibm.watson.modelmesh.ModelMeshEnvVars.MMESH_METRICS_ENV_VAR;
 import static java.util.concurrent.TimeUnit.*;
 
 /**
@@ -150,12 +149,14 @@ final class PrometheusMetrics implements Metrics {
                 5000, 10000, 20000, 60000, 120000, 300000
         };
 
+        private static final int INFO_METRICS_MAX = 5;
+
         private final CollectorRegistry registry;
         private final NettyServer metricServer;
         private final boolean shortNames;
         private final EnumMap<Metric, Collector> metricsMap = new EnumMap<>(Metric.class);
 
-        public PrometheusMetrics(Map<String, String> params) throws Exception {
+        public PrometheusMetrics(Map<String, String> params, Map<String, String> infoMetricParams) throws Exception {
             int port = 2112;
             boolean shortNames = true;
             boolean https = true;
@@ -230,6 +231,24 @@ public PrometheusMetrics(Map<String, String> params) throws Exception {
                 }
             }
 
+            if (infoMetricParams != null && !infoMetricParams.isEmpty()){
+                if (infoMetricParams.size() > INFO_METRICS_MAX) {
+                    throw new Exception("Too many info metrics provided in env var " + MMESH_CUSTOM_ENV_VAR + ": \""
+                            + infoMetricParams+ "\". The max is " + INFO_METRICS_MAX);
+                }
+
+                String metric_name = infoMetricParams.remove("metric_name");
+                String[] labelNames = infoMetricParams.keySet().toArray(String[]::new);
+                String[] labelValues = Stream.of(labelNames).map(infoMetricParams::get).toArray(String[]::new);
+                Gauge infoMetricsGauge = Gauge.build()
+                        .name(metric_name)
+                        .help("Info Metrics")
+                        .labelNames(labelNames)
+                        .create();
+                infoMetricsGauge.labels(labelValues).set(1.0);
+                registry.register(infoMetricsGauge);
+            }
+
             this.metricServer = new NettyServer(registry, port, https);
             this.shortNames = shortNames;
 

src/main/java/com/ibm/watson/modelmesh/ModelMesh.java

@@ -925,7 +925,9 @@ protected final TProcessor initialize() throws Exception {
 //    }
 
     // "type" or "type:p1=v1;p2=v2;...;pn=vn"
-    private static final Pattern METRICS_CONFIG_PATT = Pattern.compile("([a-z]+)(:\\w+=[^;]+(?:;\\w+=[^;]+)*)?");
+    private static final Pattern METRICS_CONFIG_PATT = Pattern.compile("([a-z;]+)(:\\w+=[^;]+(?:;\\w+=[^;]+)*)?");
+    // "metric_name" or "metric:name;l1=v1,l2=v2,...,ln=vn,"
+    private static final Pattern CUSTOM_METRIC_CONFIG_PATT = Pattern.compile("([a-z_:]+);(\\w+=[^;]+(?:;\\w+=[^,]+)*)?");
 
     private static Metrics setUpMetrics() throws Exception {
         if (System.getenv("MM_METRICS_STATSD_PORT") != null || System.getenv("MM_METRICS_PROMETHEUS_PORT") != null) {
@@ -958,12 +960,38 @@ private static Metrics setUpMetrics() throws Exception {
                 params.put(kv[0], kv[1]);
             }
         }
+        String infoMetricConfig = getStringParameter(MMESH_CUSTOM_ENV_VAR, null);
+        Map<String, String> infoMetricParams;
+        if (infoMetricConfig == null) {
+            logger.info("{} returned null", MMESH_CUSTOM_ENV_VAR);
+            infoMetricParams = null;
+        } else {
+            logger.info("{} set to \"{}\"", MMESH_CUSTOM_ENV_VAR, infoMetricConfig);
+            Matcher infoMetricMatcher = CUSTOM_METRIC_CONFIG_PATT.matcher(infoMetricConfig);
+            if (!infoMetricMatcher.matches()) {
+                throw new Exception("Invalid metrics configuration provided in env var " + MMESH_CUSTOM_ENV_VAR + ": \""
+                                    + infoMetricConfig + "\"");
+            }
+            String infoMetricName = infoMetricMatcher.group(1);
+            String infoMetricParamString = infoMetricMatcher.group(2);
+            infoMetricParams = new HashMap<>();
+            infoMetricParams.put("metric_name", infoMetricName);
+            for (String infoMetricParam : infoMetricParamString.substring(0).split(",")) {
+                String[] kv = infoMetricParam.split("=");
+                String value = System.getenv(kv[1]);
+                if (value == null) {
+                    throw new Exception("Env var " + kv[1] + " is unresolved in " + MMESH_CUSTOM_ENV_VAR + ": \""
+                            + infoMetricConfig + "\"");
+                }
+                infoMetricParams.put(kv[0], value);
+            }
+        }
         try {
             switch (type.toLowerCase()) {
             case "statsd":
                 return new Metrics.StatsDMetrics(params);
             case "prometheus":
-                return new Metrics.PrometheusMetrics(params);
+                return new Metrics.PrometheusMetrics(params, infoMetricParams);
             case "disabled":
                 logger.info("Metrics publishing is disabled (env var {}={})", MMESH_METRICS_ENV_VAR, metricsConfig);
                 return Metrics.NO_OP_METRICS;

src/main/java/com/ibm/watson/modelmesh/ModelMeshEnvVars.java

@@ -50,6 +50,7 @@ private ModelMeshEnvVars() {}
     public static final String LOAD_FAILURE_EXPIRY_ENV_VAR = "MM_LOAD_FAILURE_EXPIRY_TIME_MS";
 
     public static final String MMESH_METRICS_ENV_VAR = "MM_METRICS";
+    public static final String MMESH_CUSTOM_ENV_VAR = "MM_INFO_METRICS";
 
     public static final String LOG_EACH_INVOKE_ENV_VAR = "MM_LOG_EACH_INVOKE";
     public static final String SEND_DEST_ID_ENV_VAR = "MM_SEND_DEST_ID";

src/test/java/com/ibm/watson/modelmesh/ModelMeshMetricsTest.java

@@ -68,6 +68,12 @@ protected int requestCount() {
 
     static final String SCHEME = "https"; // or http
 
+    static final String METRIC_NAME = "assistant_deployment_info:relabel";
+    static final String DEPLOYMENT_NAME = "ga-tf-mm";
+    static final String SLOT_NAME = "ga";
+    static final String COMPONENT_NAME = "tf-mm";
+    static final String GROUP_NAME = "clu";
+
     @Override
     protected Map<String, String> extraEnvVars() {
         return  ImmutableMap.of("MM_METRICS", "prometheus:port=" + METRICS_PORT + ";scheme=" + SCHEME);
@@ -84,7 +90,7 @@ public void metricsTest() throws Exception {
 
             // verify not found status
             ModelStatusInfo status = manageModels.getModelStatus(GetStatusRequest.newBuilder()
-                    .setModelId("i don't exist").build());
+                    .setModelId("I don't exist").build());
 
             assertEquals(ModelStatus.NOT_FOUND, status.getStatus());
             assertEquals(0, status.getErrorsCount());
@@ -166,7 +172,6 @@ public void verifyMetrics() throws Exception {
                 .filter(Matcher::matches)
                 .collect(Collectors.toMap(m -> m.group(1), m -> Double.parseDouble(m.group(2))));
 
-
         System.out.println(metrics.size() + " metrics scraped");
 
         // Spot check some expected metrics and values
@@ -198,5 +203,10 @@ public void verifyMetrics() throws Exception {
         assertEquals(0.0, metrics.get("jvm_buffer_pool_used_buffers{pool=\"mapped\",}")); // mmapped memory not used
         assertTrue(metrics.containsKey("jvm_gc_collection_seconds_sum{gc=\"G1 Young Generation\",}"));
         assertTrue(metrics.containsKey("jvm_memory_bytes_committed{area=\"heap\",}"));
+
+        // Info metrics
+        assertEquals(1.0, metrics.get(METRIC_NAME + "{component=\"" + COMPONENT_NAME
+                + "\",slot=\"" + SLOT_NAME + "\",deployment=\"" + DEPLOYMENT_NAME + "\",group=\"" + GROUP_NAME + "\",}"));
     }
-}
+
+}