Externalize build properties.

See #715.

Jenkinsfile

@@ -1,3 +1,9 @@
+def p = [:]
+node {
+    checkout scm
+    p = readProperties interpolate: true, file: 'ci/pipeline.properties'
+}
+
 pipeline {
 	agent none
 
@@ -33,7 +39,7 @@ pipeline {
 			steps {
 				script {
 					docker.withRegistry('', 'hub.docker.com-springbuildmaster') {
-						docker.image('openjdk:17-bullseye').inside('-u root -v /var/run/docker.sock:/var/run/docker.sock -v /usr/bin/docker:/usr/bin/docker -v $HOME:/tmp/jenkins-home') {
+						docker.image(p['docker.java.lts.image']).inside(p['docker.java.inside.docker']) {
 							sh "docker login --username ${DOCKER_HUB_USR} --password ${DOCKER_HUB_PSW}"
 							sh 'PROFILE=ci ci/test.sh'
 							sh "ci/clean.sh"
@@ -63,7 +69,7 @@ pipeline {
 			steps {
 				script {
 					docker.withRegistry('', 'hub.docker.com-springbuildmaster') {
-						docker.image('openjdk:17-bullseye').inside('-v $HOME:/tmp/jenkins-home') {
+						docker.image(p['docker.java.main.image']).inside(p['docker.java.inside.basic']) {
 							sh 'MAVEN_OPTS="-Duser.name=jenkins -Duser.home=/tmp/jenkins-home" ./mvnw -s settings.xml -Pci,artifactory -Dmaven.repo.local=/tmp/jenkins-home/.m2/spring-data-r2dbc-non-root ' +
 									'-Dartifactory.server=https://repo.spring.io ' +
 									"-Dartifactory.username=${ARTIFACTORY_USR} " +

ci/pipeline.properties

@@ -0,0 +1,23 @@
+# Java versions
+java.main.tag=17.0.2_8-jdk
+
+# Docker container images - standard
+docker.java.main.image=eclipse-temurin:${java.main.tag}
+
+# Supported versions of MongoDB
+docker.mongodb.4.4.version=4.4.4
+docker.mongodb.5.0.version=5.0.3
+
+# Supported versions of Redis
+docker.redis.6.version=6.2.4
+
+# Supported versions of Cassandra
+docker.cassandra.3.version=3.11.11
+
+# Docker environment settings
+docker.java.inside.basic=-v $HOME:/tmp/jenkins-home
+docker.java.inside.docker=-u root -v /var/run/docker.sock:/var/run/docker.sock -v /usr/bin/docker:/usr/bin/docker -v $HOME:/tmp/jenkins-home
+
+# Credentials
+docker.registry=
+docker.credentials=hub.docker.com-springbuildmaster