administrator dashboard for observing the Docker container pool

app/assets/javascripts/dashboard.js

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+$(function() {
+  var REFRESH_INTERVAL = 5000;
+
+  var refreshData = function() {
+    var jqxhr = $.ajax({
+      dataType: 'json',
+      method: 'GET'
+    });
+    jqxhr.done(updateView);
+  };
+
+  var updateProgressBar = function(progress_bar, data) {
+    var percentage = Math.round(data.quantity / data.pool_size * 100);
+    progress_bar.attr({
+      'aria-valuemax': data.pool_size,
+      'aria-valuenow': data.quantity,
+      style: 'width: ' + percentage + '%'
+    });
+    progress_bar.html(data.quantity);
+  };
+
+  var updateView = function(response) {
+    _.each(response.docker, function(data) {
+      var row = $('tbody tr[data-id=' + data.id + ']');
+      $('.pool-size', row).html(data.pool_size);
+      var progress_bar = $('.quantity .progress .progress-bar', row);
+      updateProgressBar(progress_bar, data);
+    });
+  };
+
+  if ($.isController('dashboard')) {
+    refreshData();
+    setInterval(refreshData, REFRESH_INTERVAL);
+  }
+});

app/controllers/admin/dashboard_controller.rb

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+module Admin
+  class DashboardController < ApplicationController
+    include DashboardHelper
+
+    def policy_class
+      DashboardPolicy
+    end
+
+    def show
+      authorize(self)
+      respond_to do |format|
+        format.html
+        format.json { render(json: dashboard_data) }
+      end
+    end
+  end
+end

app/helpers/admin/dashboard_helper.rb

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+module Admin
+  module DashboardHelper
+    def dashboard_data
+      {docker: docker_data}
+    end
+
+    def docker_data
+      ExecutionEnvironment.order(:id).select(:id, :permitted_execution_time, :pool_size).map do |execution_environment|
+        execution_environment.attributes.merge(quantity: DockerContainerPool.quantities[execution_environment.id])
+      end
+    end
+  end
+end

app/policies/admin/dashboard_policy.rb

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+module Admin
+  class DashboardPolicy < AdminOnlyPolicy
+  end
+end

app/views/admin/dashboard/show.html.slim

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+h1 = t('breadcrumbs.dashboard.show')
+
+h2 Docker
+
+- if DockerContainerPool.config[:active]
+  .table-responsive
+    table.table
+      thead
+        tr
+          th = t('activerecord.models.execution_environment.one')
+          th = t('activerecord.attributes.execution_environment.pool_size')
+          th = t('.quantity')
+      tbody
+        - ExecutionEnvironment.order(:name).each do |execution_environment|
+          tr data-id=execution_environment.id
+            td = link_to(execution_environment, execution_environment)
+            td.pool-size
+            td.quantity = progress_bar(0)
+- else
+  p = t('.inactive')