Fix parsing _count metrics and keep just custom labels in the labels …

…variable (#181)

## Description

This PR fixes two issues that I encountered during testing the new
metrics collector:

1) in case that we have metric with `_count` suffix and there is no
histogram or summary, the metric is simply skipped. This is resolved by
adding check for `TYPE` line where the type of the metric is parsed and
in case that we go with the `_count` branch, which doesn't fit to the
histogram or summary, it will pick type based on this variable
2) in case that the name is same, but the labels are different, we are
putting everything into the first metric (so the labels difference is
really ignored). This is now fixed by comparing the "custom labels" in
the current histogram/summary and the newly parsed (again custom) labels
from the new metric.

## Type of Change

* Bug fix

## Checklist

- [X] My code follows the style guidelines of this project
- [X] I have performed a self-review of my own code
- [X] I have commented my code, particularly in hard-to-understand areas
- [X] I have made corresponding changes to the documentation
- [X] My changes generate no new warnings
- [X] I have added tests that prove my fix is effective or that my
feature works
- [X] New and existing unit/integration tests pass locally with my
changes

test-frame-metrics-collector/src/main/java/io/skodjob/testframe/metrics/PrometheusTextFormatParser.java

@@ -32,47 +32,69 @@ public static List<Metric> parse(String data) throws IOException {
         List<Metric> metrics = new ArrayList<>();
         BufferedReader reader = new BufferedReader(new StringReader(data));
         String line;
+        String type = "";
         Histogram currentHistogram = null;
         Summary currentSummary = null;
 
         while ((line = reader.readLine()) != null) {
+            String[] parts = line.split(" ");
+
             if (line.startsWith("#")) {
-                continue; // Skip comments and type/help definitions
+                if (line.contains("TYPE")) {
+                    type = parts[3];
+                }
+                continue; // Skip comments and help definition
             }
-            String[] parts = line.split(" ");
+
             if (parts.length == 2) {
                 String metricNameAndLabels = parts[0];
                 double value = Double.parseDouble(parts[1]);
 
                 String[] nameAndLabels = parseNameAndLabels(metricNameAndLabels);
                 String name = nameAndLabels[0];
                 Map<String, String> labels = parseLabels(nameAndLabels[1]);
+                // `customLabels` represents labels that are not part of the Prometheus metrics
+                // (like buckets or summary) - the `le` and `quantile` labels are removed,
+                // because they are parsed in a different way
+                Map<String, String> customLabels = getCustomLabels(labels);
 
                 if (name.endsWith("_total")) {
-                    metrics.add(new Counter(name, labels, line, value));
+                    metrics.add(new Counter(name, customLabels, line, value));
                 } else if (name.contains("_bucket")) {
-                    if (currentHistogram == null || !currentHistogram.name.equals(name)) {
-                        currentHistogram = new Histogram(name, labels, line);
+                    if (currentHistogram == null || !currentHistogram.name.equals(name)
+                        || !currentHistogram.labels.equals(customLabels)) {
+                        currentHistogram = new Histogram(name, customLabels, line);
                         metrics.add(currentHistogram);
                     }
                     double upperBound = labels.get("le").contains("+Inf") ?
                         Double.MAX_VALUE : Double.parseDouble(labels.get("le"));
                     currentHistogram.addBucket(upperBound, value);
                 } else if (name.endsWith("_sum")) {
-                    if (currentHistogram != null && currentHistogram.name.equals(name.replace("_sum", "_bucket"))) {
+                    if (currentHistogram != null && currentHistogram.name.equals(name.replace("_sum", "_bucket"))
+                        && currentHistogram.labels.equals(customLabels)) {
                         currentHistogram.setSum(value);
-                    } else if (currentSummary != null && currentSummary.name.equals(name.replace("_sum", ""))) {
+                    } else if (currentSummary != null && currentSummary.name.equals(name.replace("_sum", ""))
+                        && currentSummary.labels.equals(customLabels)) {
                         currentSummary.setSum(value);
                     }
                 } else if (name.endsWith("_count")) {
-                    if (currentHistogram != null && currentHistogram.name.equals(name.replace("_count", "_bucket"))) {
+                    if (currentHistogram != null && currentHistogram.name.equals(name.replace("_count", "_bucket"))
+                        && currentHistogram.labels.equals(customLabels)) {
                         currentHistogram.setCount((int) value);
-                    } else if (currentSummary != null && currentSummary.name.equals(name.replace("_count", ""))) {
+                    } else if (currentSummary != null && currentSummary.name.equals(name.replace("_count", ""))
+                        && currentSummary.labels.equals(customLabels)) {
                         currentSummary.setCount((int) value);
+                    } else if (type != null) {
+                        if (type.equals("gauge")) {
+                            metrics.add(new Gauge(name, customLabels, line, value));
+                        } else if (type.equals("counter")) {
+                            metrics.add(new Counter(name, customLabels, line, value));
+                        }
                     }
                 } else if (name.contains("{quantile=")) {
-                    if (currentSummary == null || !currentSummary.name.equals(name)) {
-                        currentSummary = new Summary(name, labels, line);
+                    if (currentSummary == null || !currentSummary.name.equals(name)
+                        || !currentSummary.labels.equals(customLabels)) {
+                        currentSummary = new Summary(name, customLabels, line);
                         metrics.add(currentSummary);
                     }
                     double quantile = Double.parseDouble(labels.get("quantile"));
@@ -85,6 +107,22 @@ public static List<Metric> parse(String data) throws IOException {
         return metrics;
     }
 
+    /**
+     * Method that "removes" Prometheus labels (connected to buckets or summary) and returns just the custom labels
+     * provided by the user or application.
+     *
+     * @param labels    parsed labels from the Prometheus metric
+     * @return  custom labels from the metric
+     */
+    private static Map<String, String> getCustomLabels(Map<String, String> labels) {
+        Map<String, String> customLabels = new HashMap<>(labels);
+
+        customLabels.remove("le");
+        customLabels.remove("quantile");
+
+        return customLabels;
+    }
+
     private static String[] parseNameAndLabels(String metricNameAndLabels) {
         int labelStartIndex = metricNameAndLabels.indexOf('{');
         if (labelStartIndex == -1) {