misc: add Jenkins pipeline for build validation and deployment

* _build/Dockerfile.build: New Dockerfile for docs-build pipeline,
with the required tools for building the docs installed.
* _build/Jenkinsfile.build: New Jenkinsfile defining the docs-build
pipeline.

Change-Id: If50e687a5b9342eb2dcb5cb39e8a63db91f8616d

_build/Dockerfile.build

+FROM debian:bullseye-slim
+
+ARG UID=1000
+ARG GID=1000
+
+ENV DEBIAN_FRONTEND=noninteractive
+
+RUN apt-get clean
+RUN apt-get update && \
+    apt-get install -y -o Acquire::Retries=10 \
+        curl \
+        make \
+        python3-pip
+
+RUN groupadd -g "${GID}" jenkins && \
+    useradd --create-home --no-log-init -u "${UID}" -g "${GID}" jenkins
+
+USER jenkins
+
+ENV PATH="/home/jenkins/.local/bin:${PATH}"
+
+RUN pip3 install Sphinx sphinx-intl sphinx-rtd-theme myst-parser

_build/Jenkinsfile.build

+// Copyright (C) 2022 Savoir-faire Linux Inc.
+//
+// Author: Amin Bandali <amin.bandali@savoirfairelinux.com>
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+//
+// Build (both validation and deployment) of jami-docs.
+
+// Configuration globals.
+def REPO_NAME = 'jami-docs'
+def DL_SSH_KEY = '5825b39b-dfc6-435f-918e-12acc1f56221'
+def REMOTE_HOST = env.SSH_HOST_DL_RING_CX
+def REMOTE_BASE_DIR = '/srv/repository/ring/docs'
+def DOCKER_IMAGE = "docs-build:${BUILD_ID}"
+def DOCKER_FILE = '_build/Dockerfile.build'
+
+pipeline {
+    agent {
+        label 'linux-builder'
+    }
+
+    triggers {
+        gerrit customUrl: '',
+        gerritProjects: [
+            [branches: [[compareType: 'PLAIN', pattern: 'master']],
+             compareType: 'PLAIN',
+             disableStrictForbiddenFileVerification: false,
+             pattern: REPO_NAME]],
+        triggerOnEvents: [
+            commentAddedContains('!build'),
+            patchsetCreated(excludeDrafts: true,
+                            excludeNoCodeChange: true,
+                            excludeTrivialRebase: true),
+            changeMerged()]
+    }
+
+    options {
+        ansiColor('xterm')
+    }
+
+    parameters {
+        string(name: 'GERRIT_REFSPEC',
+               defaultValue: 'refs/heads/master',
+               description: 'The Gerrit refspec to fetch.')
+    }
+
+    stages {
+        stage('Build docs-build docker image') {
+            steps {
+                script {
+                    def jenkinsUID = sh(returnStdout: true, script: 'id -u jenkins').replaceAll("\n", '').trim()
+                    def jenkinsGID = sh(returnStdout: true, script: 'id -g jenkins').replaceAll("\n", '').trim()
+                    def docker_args =
+                        ["--build-arg UID=${jenkinsUID}",
+                         "--build-arg GID=${jenkinsGID}",
+                         "-f ${DOCKER_FILE} ."].join(' ')
+                    docker.build(DOCKER_IMAGE, docker_args)
+                }
+            }
+        }
+
+        stage('Run docs-build docker image') {
+            steps {
+                script {
+                    def pwd = pwd()
+                    def docker_args = "-t -v ${pwd}:/${REPO_NAME}:rw -e BATCH_MODE=1"
+                    docker.image(DOCKER_IMAGE).withRun(docker_args) { container ->
+                        def run_cmd = { cmd ->
+                            sh "set +x; docker exec -t ${container.id} /bin/sh -c '${cmd}'"
+                        }
+                        stage('Build docs') {
+                            run_cmd("""
+                                cd ${REPO_NAME}
+                                make html
+                            """)
+                        }
+                    }
+                }
+            }
+        }
+
+        stage('Deploy docs') {
+            when {
+                environment name: 'GERRIT_EVENT_TYPE',
+                            value: 'change-merged'
+            }
+            environment {
+                RSYNC_DEST = "${REMOTE_HOST}:${REMOTE_BASE_DIR}"
+            }
+            steps {
+                sshagent(credentials: [DL_SSH_KEY]) {
+                    script { sh 'make deploy' }
+                }
+            }
+        }
+    }
+}