Fix monitoring dashboard not working properly

This fixes a bug when the monitoring dashboard wouldn't redraw for when the sidebar
was collapsed/expanded on medium to small screens. This is done by enforcing vue
to update based on the change of a key

5 files changed, 66 insertions, 47 deletions

diff --git a/app/assets/javascripts/monitoring/components/dashboard.vue b/app/assets/javascripts/monitoring/components/dashboard.vue
index ae96ac3b80c..524f4d1f568 100644
--- a/app/assets/javascripts/monitoring/components/dashboard.vue
+++ b/app/assets/javascripts/monitoring/components/dashboard.vue
@@ -97,33 +97,45 @@ export default {
       store: new MonitoringStore(),
       state: 'gettingStarted',
       showEmptyState: true,
-      updateAspectRatio: false,
-      updatedAspectRatios: 0,
       hoverData: {},
-      resizeThrottled: {},
+      updateDashboardKeyNumber: 0,
     };
   },
+  computed: {
+    forceRedraw() {
+      return `dashboard-key-${this.updateDashboardKeyNumber}`;
+    },
+  },
   created() {
     this.service = new MonitoringService({
       metricsEndpoint: this.metricsEndpoint,
       deploymentEndpoint: this.deploymentEndpoint,
       environmentsEndpoint: this.environmentsEndpoint,
     });
-    eventHub.$on('toggleAspectRatio', this.toggleAspectRatio);
+    this.mutationObserverConfig = {
+      attributes: true,
+      childList: false,
+      subtree: false,
+    };
     eventHub.$on('hoverChanged', this.hoverChanged);
   },
   beforeDestroy() {
-    eventHub.$off('toggleAspectRatio', this.toggleAspectRatio);
     eventHub.$off('hoverChanged', this.hoverChanged);
     window.removeEventListener('resize', this.resizeThrottled, false);
+    this.sidebarMutationObserver.disconnect();
   },
   mounted() {
-    this.resizeThrottled = _.throttle(this.resize, 600);
+    this.resizeThrottled = _.debounce(this.resize, 100);
     if (!this.hasMetrics) {
       this.state = 'gettingStarted';
     } else {
       this.getGraphsData();
       window.addEventListener('resize', this.resizeThrottled, false);
+
+      const sidebarEl = document.querySelector('.nav-sidebar');
+      // The sidebar listener
+      this.sidebarMutationObserver = new MutationObserver(this.resizeThrottled);
+      this.sidebarMutationObserver.observe(sidebarEl, this.mutationObserverConfig);
     }
   },
   methods: {
@@ -153,14 +165,7 @@ export default {
         });
     },
     resize() {
-      this.updateAspectRatio = true;
-    },
-    toggleAspectRatio() {
-      this.updatedAspectRatios += 1;
-      if (this.store.getMetricsCount() === this.updatedAspectRatios) {
-        this.updateAspectRatio = !this.updateAspectRatio;
-        this.updatedAspectRatios = 0;
-      }
+      this.updateDashboardKeyNumber += 1;
     },
     hoverChanged(data) {
       this.hoverData = data;
@@ -172,6 +177,7 @@ export default {
 <template>
   <div
     v-if="!showEmptyState"
+    :key="forceRedraw"
     class="prometheus-graphs prepend-top-default"
   >
     <div class="environments d-flex align-items-center">
@@ -218,7 +224,6 @@ export default {
         :key="index"
         :graph-data="graphData"
         :hover-data="hoverData"
-        :update-aspect-ratio="updateAspectRatio"
         :deployment-data="store.deploymentData"
         :project-path="projectPath"
         :tags-path="tagsPath"
diff --git a/app/assets/javascripts/monitoring/components/graph.vue b/app/assets/javascripts/monitoring/components/graph.vue
index a13f30e6079..ff44f51b8f8 100644
--- a/app/assets/javascripts/monitoring/components/graph.vue
+++ b/app/assets/javascripts/monitoring/components/graph.vue
@@ -32,10 +32,6 @@ export default {
       type: Object,
       required: true,
     },
-    updateAspectRatio: {
-      type: Boolean,
-      required: true,
-    },
     deploymentData: {
       type: Array,
       required: true,
@@ -110,15 +106,6 @@ export default {
     },
   },
   watch: {
-    updateAspectRatio() {
-      if (this.updateAspectRatio) {
-        this.graphHeight = 450;
-        this.graphWidth = 600;
-        this.measurements = measurements.large;
-        this.draw();
-        eventHub.$emit('toggleAspectRatio');
-      }
-    },
     hoverData() {
       this.positionFlag();
     },
diff --git a/changelogs/unreleased/jivl-fix-monitoring-dashboard-resizing-navbar.yml b/changelogs/unreleased/jivl-fix-monitoring-dashboard-resizing-navbar.yml
new file mode 100644
index 00000000000..c21301bf6b3
--- /dev/null
+++ b/changelogs/unreleased/jivl-fix-monitoring-dashboard-resizing-navbar.yml
@@ -0,0 +1,5 @@
+---
+title: Fix resizing of monitoring dashboard
+merge_request: 21730
+author:
+type: fixed
diff --git a/spec/javascripts/monitoring/dashboard_spec.js b/spec/javascripts/monitoring/dashboard_spec.js
index 997163c7602..a1953382531 100644
--- a/spec/javascripts/monitoring/dashboard_spec.js
+++ b/spec/javascripts/monitoring/dashboard_spec.js
@@ -25,7 +25,10 @@ describe('Dashboard', () => {
   };
 
   beforeEach(() => {
-    setFixtures('<div class="prometheus-graphs"></div>');
+    setFixtures(`
+      <div class="prometheus-graphs"></div>
+      <div class="nav-sidebar"></div> 
+    `);
     DashboardComponent = Vue.extend(Dashboard);
   });
 
@@ -127,4 +130,41 @@ describe('Dashboard', () => {
       });
     });
   });
+
+  describe('when the window resizes', () => {
+    let mock;
+    beforeEach(() => {
+      mock = new MockAdapter(axios);
+      mock.onGet(mockApiEndpoint).reply(200, metricsGroupsAPIResponse);
+      jasmine.clock().install();
+    });
+
+    afterEach(() => {
+      mock.restore();
+      jasmine.clock().uninstall();
+    });
+
+    it('rerenders the dashboard when the sidebar is resized', done => {
+      const component = new DashboardComponent({
+        el: document.querySelector('.prometheus-graphs'),
+        propsData: { ...propsData, hasMetrics: true, showPanels: false },
+      });
+
+      expect(component.forceRedraw).toEqual('dashboard-key-0');
+
+      const navSidebarEl = document.querySelector('.nav-sidebar');
+      navSidebarEl.classList.add('nav-sidebar-collapsed');
+
+      Vue.nextTick()
+        .then(() => {
+          jasmine.clock().tick(1000);
+          return Vue.nextTick();
+        })
+        .then(() => {
+          expect(component.forceRedraw).toEqual('dashboard-key-1');
+          done();
+        })
+        .catch(done.fail);
+    });
+  });
 });
diff --git a/spec/javascripts/monitoring/graph_spec.js b/spec/javascripts/monitoring/graph_spec.js
index 990619b4109..99180e4d303 100644
--- a/spec/javascripts/monitoring/graph_spec.js
+++ b/spec/javascripts/monitoring/graph_spec.js
@@ -1,7 +1,6 @@
 import Vue from 'vue';
 import Graph from '~/monitoring/components/graph.vue';
 import MonitoringMixins from '~/monitoring/mixins/monitoring_mixins';
-import eventHub from '~/monitoring/event_hub';
 import {
   deploymentData,
   convertDatesMultipleSeries,
@@ -69,23 +68,6 @@ describe('Graph', () => {
     });
   });
 
-  it('sends an event to the eventhub when it has finished resizing', done => {
-    const component = createComponent({
-      graphData: convertedMetrics[1],
-      updateAspectRatio: false,
-      deploymentData,
-      tagsPath,
-      projectPath,
-    });
-    spyOn(eventHub, '$emit');
-
-    component.updateAspectRatio = true;
-    Vue.nextTick(() => {
-      expect(eventHub.$emit).toHaveBeenCalled();
-      done();
-    });
-  });
-
   it('has a title for the y-axis and the chart legend that comes from the backend', () => {
     const component = createComponent({
       graphData: convertedMetrics[1],