Fixes Issue 29 - Support metric probes with no labels

docs/configuration.md

@@ -102,6 +102,10 @@ probes:
         AND trunc(TO_DATE(s.last_load_time, 'YYYY-MM-DD/HH24:MI:SS')) >= trunc(SYSDATE - 1)
         ORDER BY elapsed_time DESC)
         WHERE ROWNUM <= 5;
+  - name: noLabels
+    type: exists
+    query: SELECT 1 FROM DUAL
+    metricName: no_labels
 ```
 
 ## passwords.yml

src/main/java/io/github/tjheslin1/patterdale/metrics/probe/Probe.java

@@ -19,6 +19,10 @@
 
 import io.github.tjheslin1.patterdale.ValueType;
 
+import java.util.stream.Collectors;
+
+import static java.lang.String.*;
+
 /**
  * The in-memory representation of probes list in 'patterdale.yml', passed in on app start-up.
  */
@@ -47,13 +51,17 @@ public Probe dbLabelled(DatabaseDefinition databaseDefinition) {
     }
 
     private String getMetricLabels(DatabaseDefinition databaseDefinition) {
-        final StringBuilder builder = new StringBuilder("database=\"").append(databaseDefinition.name).append("\",");
+        final StringBuilder builder = new StringBuilder("database=\"").append(databaseDefinition.name).append("\"");
 
         if(databaseDefinition.metricLabels != null) {
-            databaseDefinition.metricLabels.forEach((label, value) -> builder.append(label).append("=\"").append(value).append("\","));
+            builder.append(',').append(databaseDefinition.metricLabels.entrySet()
+            .stream().map(e -> format("%s=\"%s\"", e.getKey(), e.getValue()))
+            .collect(Collectors.joining(",")));
         }
 
-        builder.append(this.metricLabels);
+        if (metricLabels != null && !metricLabels.isEmpty()) {
+            builder.append(",").append(this.metricLabels);
+        }
 
         return builder.toString();
     }

src/test/java/io/github/tjheslin1/patterdale/config/ConfigUnmarshallerTest.java

@@ -79,7 +79,7 @@ private PatterdaleConfig expectedConfig() {
         expectedConfig.connectionPool = connectionPoolProperties;
 
         expectedConfig.probes = new Probe[]{
-                PROBE_1, PROBE_2
+                PROBE_1, PROBE_2, PROBE_3
         };
 
         return expectedConfig;
@@ -94,6 +94,7 @@ private PatterdaleConfig expectedConfig() {
     private static final String LIST = "list";
     private static final String METRIC_NAME = "database_up";
     private static final String METRIC_NAME_2 = "slowest_queries";
+    private static final String METRIC_NAME_3 = "no_labels";
     private static final String METRIC_LABELS = "query=\"SELECT 1 FROM DUAL\"";
     private static final String METRIC_LABELS_2 = "sqlText=\"%s\",sqlId=\"%s\",username=\"%s\",childNumber=\"%s\",diskReads=\"%s\",executions=\"%s\",firstLoadTime=\"%s\",lastLoadTime=\"%s\"";
     private static final String QUERY_SQL_1 = "SELECT 1 FROM DUAL";
@@ -113,6 +114,7 @@ private PatterdaleConfig expectedConfig() {
             "WHERE   s.parsing_user_id = d.user_id\n" +
             "AND trunc(TO_DATE(s.last_load_time, 'YYYY-MM-DD/HH24:MI:SS')) >= trunc(SYSDATE - 1)\n" +
             "ORDER BY elapsed_time DESC)\n" +
-            "WHERE ROWNUM <= 5;";
+            "WHERE ROWNUM <= 5;\n";
     private static final Probe PROBE_2 = probe("slowestQueries", QUERY_SQL_2, LIST, METRIC_NAME_2, METRIC_LABELS_2);
+    private static final Probe PROBE_3 = probe("noLabels", QUERY_SQL_1, EXISTS, METRIC_NAME_3, null);
 }

src/test/java/io/github/tjheslin1/patterdale/metrics/probe/ProbeTest.java

@@ -29,4 +29,14 @@ public void dbLabelledPassesMetricLabelsFromDatabaseDefinitionToProbe() {
 
         assertThat(got.metricLabels).isEqualTo("database=\"db\",label1=\"value1\",label2=\"value2\",probeLabel=\"probeValue\"");
     }
-}
+
+    @Test
+    public void dbLabelledWithNoMetricLabels() {
+        final Probe probe = Probe.probe("name", "SQL; ", "", "", null);
+        final Map<String, String> labels = new HashMap<>();
+        labels.put("label1", "value1");
+
+        final Probe got = probe.dbLabelled(databaseDefinition("db", "user", "url", emptyList(), labels));
+        assertThat(got.metricLabels).isEqualTo("database=\"db\",label1=\"value1\"");
+    }
+}

src/test/resources/patterdale.yml

@@ -48,4 +48,8 @@ probes:
         WHERE   s.parsing_user_id = d.user_id
         AND trunc(TO_DATE(s.last_load_time, 'YYYY-MM-DD/HH24:MI:SS')) >= trunc(SYSDATE - 1)
         ORDER BY elapsed_time DESC)
-        WHERE ROWNUM <= 5;
+        WHERE ROWNUM <= 5;
+  - name: noLabels
+    type: exists
+    query: SELECT 1 FROM DUAL
+    metricName: no_labels