fix timescale prometheus charts overlapping

app/assets/javascripts/lib/utils/datetime_utility.js

@@ -291,6 +291,15 @@ export const getTimeframeWindow = (length, date) => {
   return timeframe;
 };
+/**
+ * Returns the time difference between two dates in minutes
+ *
+ * @param {Date} dateStart
+ * @param {Date} dateEnd
+ */
+
+export const timeDifferenceMinutes = (dateStart, dateEnd) => (dateEnd - dateStart) / 1000 / 60;
+
 window.gl = window.gl || {};
 window.gl.utils = {
   ...(window.gl.utils || {}),

app/assets/javascripts/monitoring/components/graph.vue

 <script>
   import { scaleLinear, scaleTime } from 'd3-scale';
   import { axisLeft, axisBottom } from 'd3-axis';
-  import { max, extent } from 'd3-array';
+  import { max, extent, min } from 'd3-array';
   import { select } from 'd3-selection';
+  import { timeMinute } from 'd3-time';
+  import { timeDifferenceMinutes } from '~/lib/utils/datetime_utility';
   import GraphLegend from './graph/legend.vue';
   import GraphFlag from './graph/flag.vue';
   import GraphDeployment from './graph/deployment.vue';
@@ -14,7 +16,7 @@
   import createTimeSeries from '../utils/multiple_time_series';
   import bp from '../../breakpoints';
-  const d3 = { scaleLinear, scaleTime, axisLeft, axisBottom, max, extent, select };
+  const d3 = { scaleLinear, scaleTime, axisLeft, axisBottom, max, min, extent, select, timeMinute };
   export default {
     components: {
@@ -206,9 +208,23 @@
         const allValues = this.timeSeries.reduce((all, { values }) => all.concat(values), []);
         axisXScale.domain(d3.extent(allValues, d => d.time));
         axisYScale.domain([0, d3.max(allValues.map(d => d.value))]);
+        // time difference
+        const dateEnd = d3.max(allValues.map(d => d.time));
+        const dateStart = d3.min(allValues.map(d => d.time));
+        const timeDifference = timeDifferenceMinutes(dateStart, dateEnd);
+
+        let timeTicks;
+        if (timeDifference > 90) {
+          timeTicks = 60;
+        } else if (timeDifference > 45 && timeDifference <= 90) {
+          timeTicks = 30;
+        } else if (timeDifference <= 45) {
+          timeTicks = 15;
+        }
         const xAxis = d3.axisBottom()
           .scale(axisXScale)
+          .ticks(d3.timeMinute.every(timeTicks))
           .tickFormat(timeScaleFormat);
         const yAxis = d3.axisLeft()

spec/javascripts/datetime_utility_spec.js

@@ -170,3 +170,12 @@ describe('getTimeframeWindow', () => {
     });
   });
 });
+
+describe('timeDifferenceMinutes', () => {
+  it('returns the time difference between two dates in minutes', () => {
+    const dateStart = new Date('2018-03-08 12:00:00');
+    const dateEnd = new Date('2018-03-08 13:00:00');
+
+    expect(datetimeUtility.timeDifferenceMinutes(dateStart, dateEnd)).toEqual(60);
+  });
+});