[CI] Build docker image during packer_cache (elastic#82145)

# Conflicts:
#	.ci/packer_cache_for_branch.sh

.ci/build_docker.sh

@@ -0,0 +1,10 @@
+#!/bin/bash
+
+set -euo pipefail
+
+cd "$(dirname "${0}")"
+
+cp /usr/local/bin/runbld ./
+cp /usr/local/bin/bash_standard_lib.sh ./
+
+docker build -t kibana-ci -f ./Dockerfile .

.ci/packer_cache_for_branch.sh

@@ -0,0 +1,60 @@
+#!/usr/bin/env bash
+
+set -e
+
+branch="$1"
+checkoutDir="$(pwd)"
+
+if [[ "$branch" != "master" ]]; then
+  checkoutDir="/tmp/kibana-$branch"
+  git clone https://github.com/elastic/kibana.git --branch "$branch" --depth 1 "$checkoutDir"
+  cd "$checkoutDir"
+fi
+
+source src/dev/ci_setup/setup.sh;
+
+# download es snapshots
+node scripts/es snapshot --download-only;
+node scripts/es snapshot --license=oss --download-only;
+
+# download reporting browsers
+(cd "x-pack" && node ../node_modules/.bin/gulp downloadChromium);
+
+# cache the chromedriver archive
+chromedriverDistVersion="$(node -e "console.log(require('chromedriver').version)")"
+chromedriverPkgVersion="$(node -e "console.log(require('./package.json').devDependencies.chromedriver)")"
+if [ -z "$chromedriverDistVersion" ] || [ -z "$chromedriverPkgVersion" ]; then
+  echo "UNABLE TO DETERMINE CHROMEDRIVER VERSIONS"
+  exit 1
+fi
+mkdir -p .chromedriver
+curl "https://chromedriver.storage.googleapis.com/$chromedriverDistVersion/chromedriver_linux64.zip" > .chromedriver/chromedriver.zip
+echo "$chromedriverPkgVersion" > .chromedriver/pkgVersion
+
+# cache the geckodriver archive
+geckodriverPkgVersion="$(node -e "console.log(require('./package.json').devDependencies.geckodriver)")"
+if [ -z "$geckodriverPkgVersion" ]; then
+  echo "UNABLE TO DETERMINE geckodriver VERSIONS"
+  exit 1
+fi
+mkdir -p ".geckodriver"
+cp "node_modules/geckodriver/geckodriver.tar.gz" .geckodriver/geckodriver.tar.gz
+echo "$geckodriverPkgVersion" > .geckodriver/pkgVersion
+
+echo "Creating bootstrap_cache archive"
+
+# archive cacheable directories
+mkdir -p "$HOME/.kibana/bootstrap_cache"
+tar -cf "$HOME/.kibana/bootstrap_cache/$branch.tar" \
+  .chromium \
+  .es \
+  .chromedriver \
+  .geckodriver;
+
+echo "created $HOME/.kibana/bootstrap_cache/$branch.tar"
+
+.ci/build_docker.sh
+
+if [[ "$branch" != "master" ]]; then
+  rm --preserve-root -rf "$checkoutDir"
+fi

vars/kibanaPipeline.groovy

@@ -373,12 +373,7 @@ def scriptTaskDocker(description, script) {
 
 def buildDocker() {
   sh(
-    script: """
-      cp /usr/local/bin/runbld .ci/
-      cp /usr/local/bin/bash_standard_lib.sh .ci/
-      cd .ci
-      docker build -t kibana-ci -f ./Dockerfile .
-    """,
+    script: "./.ci/build_docker.sh",
     label: 'Build CI Docker image'
   )
 }