Add OpenLab CI configuration (envoyproxy#6981)

This patch adds the OpenLab CI configuration to enable
the support for Envoy arm64 build in OpenLab.

After this, each pull request in envoy will trigger the
envoy-arm64-build job which verified the arm build
on OpenLab ARM cluster.

Related: envoyproxy#1861

Signed-off-by: Yikun Jiang <[email protected]>

Author: Yikun

.zuul.yaml

@@ -0,0 +1,14 @@
+- project:
+    name: envoyproxy/envoy
+    check:
+      jobs:
+        - envoy-build-arm64
+
+- job:
+    name: envoy-build-arm64
+    parent: init-test
+    description: |
+      Envoy build in openlab cluster.
+    run: .zuul/playbooks/envoy-build/run.yaml
+    nodeset: ubuntu-xenial-arm64
+    voting: false

.zuul/playbooks/envoy-build/run.yaml

@@ -0,0 +1,28 @@
+- hosts: all
+  become: yes
+  roles:
+    - role: config-gcc
+      gcc_version: 7
+  tasks:
+    - name: Build envoy
+      shell:
+        cmd: |
+          apt update
+          apt-get update
+          apt-get install -y \
+             libtool \
+             cmake \
+             automake \
+             autoconf \
+             make \
+             ninja-build \
+             curl \
+             unzip \
+             virtualenv
+
+          bazel build //source/exe:envoy-static | tee $LOGS_PATH//bazel.txt
+
+          cp -r ./bazel-bin $RESULTS_PATH
+        chdir: '{{ zuul.project.src_dir }}'
+        executable: /bin/bash
+      environment: '{{ global_env }}'