automatically split jsg nodes

refs DE-123

Test Plan:
1. Ensure that the number of tests run per JS job is the same
2. Ensure that test reporting works correctly

flag = none

Change-Id: If25f6f4fe6af6d8982b5aed62c61c65b1d4daca9
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/242341
Tested-by: Service Cloud Jenkins <svc.cloudjenkins@instructure.com>
Reviewed-by: Ryan Norton <rnorton@instructure.com>
QA-Review: Aaron Ogata <aogata@instructure.com>
Product-Review: Aaron Ogata <aogata@instructure.com>

Jenkinsfile.js

@@ -20,11 +20,33 @@
 
 library "canvas-builds-library"
 
+def DEFAULT_NODE_COUNT = 1
+def JSG_NODE_COUNT = 3
+
 def copyFiles(dockerName, dockerPath, hostPath) {
   sh "mkdir -vp ./$hostPath"
   sh "docker cp \$(docker ps -qa -f name=$dockerName):/usr/src/app/$dockerPath ./$hostPath"
 }
 
+def makeKarmaStage(group, ciNode, ciTotal) {
+  return {
+    withEnv([
+      "CI_NODE_INDEX=${ciNode}",
+      "CI_NODE_TOTAL=${ciTotal}",
+      "CONTAINER_NAME=tests-karma-${group}-${ciNode}",
+      "JSPEC_GROUP=${group}"
+    ]) {
+      try {
+        credentials.withSentryCredentials {
+          sh 'build/new-jenkins/js/tests-karma.sh'
+        }
+      } finally {
+        copyFiles(env.CONTAINER_NAME, 'coverage-js', "./tmp/${env.CONTAINER_NAME}")
+      }
+    }
+  }
+}
+
 pipeline {
   agent { label 'canvas-docker' }
   options { ansiColor('xterm') }
@@ -86,18 +108,12 @@ pipeline {
                 sh 'build/new-jenkins/js/tests-quizzes.sh'
               }
 
-              ['coffee', 'jsa', 'jsg', 'jsh'].each { group ->
-                tests["Karma - Spec Group - ${group}"] = {
-                  withEnv(["CONTAINER_NAME=tests-karma-${group}", "JSPEC_GROUP=${group}"]) {
-                    try {
-                      credentials.withSentryCredentials {
-                        sh 'build/new-jenkins/js/tests-karma.sh'
-                      }
-                    } finally {
-                      copyFiles(env.CONTAINER_NAME, 'coverage-js', "./tmp/${env.CONTAINER_NAME}")
-                    }
-                  }
+              for(int i = 0; i < JSG_NODE_COUNT; i++) {
+                tests["Karma - Spec Group - jsg${i}"] = makeKarmaStage('jsg', i, JSG_NODE_COUNT)
               }
+
+              ['coffee', 'jsa', 'jsh'].each { group ->
+                tests["Karma - Spec Group - ${group}"] = makeKarmaStage(group, 0, DEFAULT_NODE_COUNT)
               }
             }
 

build/new-jenkins/js/tests-karma.sh

@@ -8,4 +8,4 @@ if [[ "${COVERAGE:-}" == "1" ]]; then
   sentry="-e SENTRY_URL -e SENTRY_DSN -e SENTRY_ORG -e SENTRY_PROJECT -e SENTRY_AUTH_TOKEN -e DEPRECATION_SENTRY_DSN"
 fi
 
-docker-compose run --name $CONTAINER_NAME -e COVERAGE -e FORCE_FAILURE $sentry karma yarn test:karma:headless
+docker-compose run --name $CONTAINER_NAME -e CI_NODE_INDEX -e CI_NODE_TOTAL -e COVERAGE -e FORCE_FAILURE $sentry karma yarn test:karma:headless

webpack.test.config.js

@@ -18,6 +18,7 @@
 
 process.env.NODE_ENV = 'test'
 
+const fs = require('fs')
 const path = require('path')
 const webpack = require('webpack')
 const testWebpackConfig = require('./frontend_build/baseWebpackConfig')
@@ -55,7 +56,45 @@ testWebpackConfig.plugins.push(new webpack.EnvironmentPlugin({
   GIT_COMMIT: null
 }))
 
+const getAllFiles = (dirPath, arrayOfFiles, callback) => {
+  const files = fs.readdirSync(dirPath)
+
+  files.forEach(file => {
+    if (fs.statSync(dirPath + '/' + file).isDirectory()) {
+      arrayOfFiles = getAllFiles(dirPath + '/' + file, arrayOfFiles, callback)
+    } else {
+      const filePath = callback(dirPath + '/' + file)
+
+      if (filePath) {
+        arrayOfFiles.push(filePath)
+      }
+    }
+  })
+
+  return arrayOfFiles
+}
+
+const isPartitionMatch = (resource, partitions, partitionIndex) => {
+  return isNaN(partitionIndex) || partitions[partitionIndex].indexOf(resource) >= 0
+}
+
+const makeSortedPartitions = (arr, partitionCount) => {
+  const sortedArr = arr.sort()
+  const sortedArrLength = sortedArr.length
+  const chunkSize = Math.floor(sortedArrLength / partitionCount)
+  const R = []
+
+  for (let i = 0; i < sortedArrLength; i += chunkSize) {
+    R.push(sortedArr.slice(i, i + chunkSize))
+  }
+
+  return R
+}
+
 if (process.env.JSPEC_GROUP) {
+  const nodeIndex = +process.env.CI_NODE_INDEX
+  const nodeTotal = +process.env.CI_NODE_TOTAL
+
   let ignoreResource = () => {
     throw new Error(`Unknown JSPEC_GROUP ${process.env.JSPEC_GROUP}`)
   }
@@ -75,13 +114,30 @@ if (process.env.JSPEC_GROUP) {
       )
     }
   } else if (process.env.JSPEC_GROUP === 'jsg') {
+    let partitions = null
+
+    if (!isNaN(nodeIndex) && !isNaN(nodeTotal)) {
+      const allFiles = getAllFiles(CONTEXT_JSX_SPEC, [], filePath => {
+        const relativePath = filePath.replace(CONTEXT_JSX_SPEC, '.').replace(/\.js$/, '')
+
+        return RESOURCE_JSG_SPLIT_SPEC.test(relativePath) ? relativePath : null
+      })
+
+      partitions = makeSortedPartitions(allFiles, nodeTotal)
+    }
+
     ignoreResource = (resource, context) => {
       return (
         context.endsWith(CONTEXT_COFFEESCRIPT_SPEC) ||
         context.endsWith(CONTEXT_EMBER_GRADEBOOK_SPEC) ||
         (context.endsWith(CONTEXT_JSX_SPEC) &&
           RESOURCE_JSX_SPEC.test(resource) &&
-          !RESOURCE_JSG_SPLIT_SPEC.test(resource))
+          !RESOURCE_JSG_SPLIT_SPEC.test(resource)) ||
+        (partitions &&
+          context.endsWith(CONTEXT_JSX_SPEC) &&
+          RESOURCE_JSX_SPEC.test(resource) &&
+          RESOURCE_JSG_SPLIT_SPEC.test(resource) &&
+          !isPartitionMatch(resource, partitions, nodeIndex))
       )
     }
   } else if (process.env.JSPEC_GROUP === 'jsh') {