Refactors build to use a parent pom and not rely on Docker Build Kit

This simplifies the build a lot by using a parent pom (as suggested by @trustin)

This simplifies further by moving some configuration management to `build_image`.

.dockerignore

@@ -5,6 +5,7 @@
 **/target
 
 **/.idea
+**/*.iml
 **/*.md
 
 **/Dockerfile

.github/workflows/docker-tests.yml

@@ -11,7 +11,7 @@ jobs:
   build-on-linux:
     strategy:
       matrix:
-        docker-target: [armeria, webmvc25-jetty, webmvc3-jetty, webmvc4-boot, webmvc4-jetty]
+        project: [armeria, webmvc25-jetty, webmvc3-jetty, webmvc4-boot, webmvc4-jetty]
     runs-on: ubuntu-latest
     name: Build and verify Docker images
     steps:
@@ -30,16 +30,12 @@ jobs:
         uses: actions/checkout@v2
         with:
           fetch-depth: 1
-      - name: Build Docker image openzipkin/example-brave:${{ matrix.docker-target }}-test
-        run: |
-          TARGET=${{ matrix.docker-target }}
-          DOCKER_BUILDKIT=1 docker build -f docker/Dockerfile \
-          -t openzipkin/example-brave:${TARGET}-test \
-          --target ${TARGET} --build-arg target=${TARGET} .
-      - name: Verify Docker image openzipkin/example-brave:${{ matrix.docker-target }}-test
+      - name: Build Docker image openzipkin/example-brave:${{ matrix.project }}-test
+        run:  docker/build_image ${{ matrix.project }} ${{ matrix.project }}-test
+      - name: Verify Docker image openzipkin/example-brave:${{ matrix.project }}-test
         run: |
           # This just makes sure containers run and the HEALTHCHECK works (for now..)
-          IMAGE=openzipkin/example-brave:${{ matrix.docker-target }}-test
+          IMAGE=openzipkin/example-brave:${{ matrix.project }}-test
           docker run --rm --name frontend -d ${IMAGE} frontend
           docker run --rm --name backend -d ${IMAGE} backend
           docker/bin/block-on-health frontend || exit 1

armeria/pom.xml

@@ -3,24 +3,25 @@
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
   <modelVersion>4.0.0</modelVersion>
+  <parent>
+    <groupId>io.zipkin.brave.example</groupId>
+    <artifactId>brave-example-parent</artifactId>
+    <version>1.0-SNAPSHOT</version>
+    <relativePath>../parent-pom.xml</relativePath>
+  </parent>
 
-  <groupId>io.zipkin.brave.example</groupId>
   <artifactId>brave-example-armeria</artifactId>
-  <version>1.0-SNAPSHOT</version>
   <packaging>jar</packaging>
 
   <name>brave-example-armeria</name>
-  <description>Tracing Example: Armeria</description>
+  <description>Tracing Example: Armeria/ Java 15</description>
 
   <properties>
-    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
-
-    <maven.compiler.source>1.8</maven.compiler.source>
-    <maven.compiler.target>1.8</maven.compiler.target>
+    <jre.version>15</jre.version>
+    <maven.compiler.release>8</maven.compiler.release>
 
     <!-- temporarily revert 1.1.0 until https://github.com/line/armeria/pull/3023 is discussed -->
     <armeria.version>1.0.0</armeria.version>
-    <brave.version>5.12.6</brave.version>
   </properties>
 
   <dependencies>
@@ -60,42 +61,6 @@
         <type>pom</type>
         <scope>import</scope>
       </dependency>
-      <dependency>
-        <groupId>io.zipkin.brave</groupId>
-        <artifactId>brave-bom</artifactId>
-        <version>${brave.version}</version>
-        <type>pom</type>
-        <scope>import</scope>
-      </dependency>
     </dependencies>
   </dependencyManagement>
-
-  <build>
-    <pluginManagement>
-      <plugins>
-        <plugin>
-          <groupId>org.apache.maven.plugins</groupId>
-          <artifactId>maven-dependency-plugin</artifactId>
-          <version>3.1.2</version>
-        </plugin>
-      </plugins>
-    </pluginManagement>
-
-    <plugins>
-      <plugin>
-        <artifactId>maven-compiler-plugin</artifactId>
-        <version>3.8.1</version>
-        <configuration>
-          <optimize>true</optimize>
-          <debug>true</debug>
-        </configuration>
-      </plugin>
-
-      <plugin>
-        <groupId>org.codehaus.mojo</groupId>
-        <artifactId>exec-maven-plugin</artifactId>
-        <version>3.0.0</version>
-      </plugin>
-    </plugins>
-  </build>
 </project>

docker/Dockerfile

@@ -1,5 +1,6 @@
 # These examples are setup minimally. In order to reduce repetition, these do not setup
 # non-root users and such as they are not intended to run in production anyway.
+ARG jre_image
 
 # We copy files from the context into a scratch container first to avoid a problem where docker and
 # docker-compose don't share layer hashes https://github.com/docker/compose/issues/883 normally.
@@ -11,113 +12,45 @@ COPY . /code/
 ## Use JDK 11 to build projects, as that can still compile Java 6
 FROM openzipkin/java:11.0.8-11.41.23 as install
 
-# The final stage to build. Mandatory: ex webmvc4-jetty
-ARG target
-RUN test -z "$target" && \
-    echo "'--build-arg target' must be set to same value as '--target'" && exit 1 || true
+ARG project
 
 WORKDIR /code
 COPY --from=scratch /code .
 
-# We copy the result of the build into a target-specific install directory.
-# Each end phase looks for this convention. This strategy enforces a match
-# between --target and the --build-arg target.
-WORKDIR /install/${target}
-
-# invoke the platfom-specific install script and copy the results
-RUN cd /code/$target && mvn -q --batch-mode -DskipTests package && \
-    platform=$(echo $target|cut -d- -f2) && \
-    if [ "$platform" = "armeria" ]; then platform=java;fi && \
+RUN cd $project && \
+    # Invoke the platform-specific install script
+    platform=$(echo "${project}"|cut -d- -f2) && \
+    if [ "${platform}" = "armeria" ]; then platform=java;fi && \
+    mvn -q --batch-mode -DskipTests package && \
     /code/docker/bin/install-${platform}-example && \
-    cp -rp install/* /install/${target}/ && \
-# Add start and health check scripts
-    mkdir /install/${target}/docker-bin && cd /install/${target}/docker-bin && \
-    cp -p /code/docker/bin/docker-healthcheck . && \
-    cp -p /code/docker/bin/start-${platform}-example start-brave-example
-
-FROM openzipkin/java:15.0.0-15.27.17-jre as armeria
-LABEL description="Tracing Example: Armeria/Java 15"
-
-WORKDIR /brave-example
-COPY --from=install /install/armeria/ .
-# Add HEALTHCHECK and ENTRYPOINT scripts into the default search path
-RUN mv docker-bin/* /usr/local/bin/ && rmdir docker-bin
+    # Move the completed installation root
+    mv install /install && \
+    # Add scripts used at runtime
+    cd /install/bin && \
+    cp -p /code/docker/bin/start-example-header start-brave-example && \
+    cat /code/docker/bin/start-${platform}-example >> start-brave-example && \
+    cp -p /code/docker/bin/docker-healthcheck .
 
-EXPOSE 8081 9000
+# Make the final layer that the example will run in
+FROM $jre_image
 
-ENV JAVA_OPTS="-Xms16m -Xmx16m -XX:+ExitOnOutOfMemoryError"
+# All content including binaries and logs write under WORKDIR
+ARG USER=brave-example
+WORKDIR /${USER}
 
-ENTRYPOINT ["start-brave-example"]
+# Copy binaries and config we installed earlier
+COPY --from=install --chown=${USER} /install .
 
-# We use start period of 30s to avoid marking the container unhealthy on slow or contended CI hosts
-HEALTHCHECK --interval=1s --start-period=30s --timeout=5s CMD ["docker-healthcheck"]
-
-FROM azul/zulu-openjdk-alpine:6u119-6.22.0.3 as webmvc25-jetty
-LABEL description="Tracing Example: Spring WebMVC 2.5/Servlet 2.5/Jetty 7/Java 6"
-# Adding maintainer label as we are using a 3rd party base layer
-LABEL maintainer="OpenZipkin https://zipkin.io/"
-
-WORKDIR /brave-example
-COPY --from=install /install/webmvc25-jetty/ .
 # Add HEALTHCHECK and ENTRYPOINT scripts into the default search path
-RUN mv docker-bin/* /usr/local/bin/ && rmdir docker-bin
-
-EXPOSE 8081 9000
+RUN mv bin/* /usr/local/bin/ && rm -rf bin
 
-# When using JRE 1.6, we cannot use -XX:+ExitOnOutOfMemoryError
-ENV JAVA_OPTS="-Xms16m -Xmx16m"
-ENTRYPOINT ["start-brave-example"]
+# Ensure the process doesn't run as root
+RUN adduser -g '' -h ${PWD} -D ${USER}
+USER ${USER}
 
 # We use start period of 30s to avoid marking the container unhealthy on slow or contended CI hosts
 HEALTHCHECK --interval=1s --start-period=30s --timeout=5s CMD ["docker-healthcheck"]
-
-FROM openzipkin/java:1.7.0_261-b02-jre as webmvc3-jetty
-LABEL description="Tracing Example: Spring WebMVC 3/Servlet 3.0/Jetty 8/Java 7"
-
-WORKDIR /brave-example
-COPY --from=install /install/webmvc3-jetty/ .
-# Add HEALTHCHECK and ENTRYPOINT scripts into the default search path
-RUN mv docker-bin/* /usr/local/bin/ && rmdir docker-bin
-
-EXPOSE 8081 9000
-
-ENV JAVA_OPTS="-Xms16m -Xmx16m -XX:+ExitOnOutOfMemoryError"
-
 ENTRYPOINT ["start-brave-example"]
 
-# We use start period of 30s to avoid marking the container unhealthy on slow or contended CI hosts
-HEALTHCHECK --interval=1s --start-period=30s --timeout=5s CMD ["docker-healthcheck"]
-
-FROM openzipkin/java:1.8.0_252-b09-jre as webmvc4-boot
-LABEL description="Tracing Example: Spring WebMVC 4/Spring Boot 1.5/Java 8"
-
-WORKDIR /brave-example
-COPY --from=install /install/webmvc4-boot/ .
-# Add HEALTHCHECK and ENTRYPOINT scripts into the default search path
-RUN mv docker-bin/* /usr/local/bin/ && rmdir docker-bin
-
+# Expose the default ports for the frontend and backend
 EXPOSE 8081 9000
-
-ENV JAVA_OPTS="-Xms32m -Xmx64m -XX:+ExitOnOutOfMemoryError"
-
-ENTRYPOINT ["start-brave-example"]
-
-# We use start period of 30s to avoid marking the container unhealthy on slow or contended CI hosts
-HEALTHCHECK --interval=1s --start-period=30s --timeout=5s CMD ["docker-healthcheck"]
-
-FROM openzipkin/java:1.8.0_252-b09-jre as webmvc4-jetty
-LABEL description="Tracing Example: Spring WebMVC 4/Servlet 3.1/Jetty 9/Java 8"
-
-WORKDIR /brave-example
-COPY --from=install /install/webmvc4-jetty/ .
-# Add HEALTHCHECK and ENTRYPOINT scripts into the default search path
-RUN mv docker-bin/* /usr/local/bin/ && rmdir docker-bin
-
-EXPOSE 8081 9000
-
-ENV JAVA_OPTS="-Xms16m -Xmx16m -XX:+ExitOnOutOfMemoryError"
-
-ENTRYPOINT ["start-brave-example"]
-
-# We use start period of 30s to avoid marking the container unhealthy on slow or contended CI hosts
-HEALTHCHECK --interval=1s --start-period=30s --timeout=5s CMD ["docker-healthcheck"]

docker/RATIONALE.md

@@ -1,12 +1,8 @@
 # docker rationale
 
-## Why do we set `--build-arg target` to the same value as `--target`?
+## Why does `build_image` manually parse XML?
 
-There are very few differences in our docker images from a scripting point of
-view. However, each has different contents, and most have a different base
-layer. We need to know the target stage before we create it, so that we can
-build the right contents. There's no known way to read the value of the
-`--target` parameter. Hence, we duplicate it as a build argument.
-
-One impact of doing this is `DOCKER_BUILDKIT=1` or similar is required to skip
-unused phases present in the process of building the image.
+`build_image` is a script used to build Docker images per project. We need
+some details from the pom file for build arguments. Rather than require
+installing an XML parser or invoking Maven, this uses `sed` which is commonly
+present on developer laptions and CI nodes.

docker/README.md

@@ -24,27 +24,9 @@ services:
 
 ## Building images
 
-To build the Armeria/Java 15 example:
-```bash
-$ DOCKER_BUILDKIT=1 docker build -t openzipkin/example-brave:armeria -f docker/Dockerfile --target armeria --build-arg target=armeria .
-```
-
-To build the Spring WebMVC 2.5/Servlet 2.5/Jetty 7/Java 6 example:
-```bash
-$ DOCKER_BUILDKIT=1 docker build -t openzipkin/example-brave:webmvc25-jetty -f docker/Dockerfile --target webmvc25-jetty --build-arg target=webmvc25-jetty .
-```
-
-To build the Spring WebMVC 3/Servlet 3.0/Jetty 8/Java 7 example:
-```bash
-$ DOCKER_BUILDKIT=1 docker build -t openzipkin/example-brave:webmvc3-jetty -f docker/Dockerfile --target webmvc3-jetty --build-arg target=webmvc3-jetty .
-```
-
-To build the Spring WebMVC 4/Spring Boot 1.5/Java 8 example:
-```bash
-$ DOCKER_BUILDKIT=1 docker build -t openzipkin/example-brave:webmvc4-boot -f docker/Dockerfile --target webmvc4-boot --build-arg target=webmvc4-boot .
-```
+To build an example, from the root directory, invoke `docker/build_image YOUR_PROJECT`:
 
-To build the Spring WebMVC 4/Servlet 3.1/Jetty 9/Java 8 example:
+Ex. To build the Armeria example as the image 'openzipkin/example-brave:test'
 ```bash
-$ DOCKER_BUILDKIT=1 docker build -t openzipkin/example-brave:webmvc4-jetty -f docker/Dockerfile --target webmvc4-jetty --build-arg target=webmvc4-jetty .
+$ docker/build_image armeria test
 ```

docker/bin/install-boot-example

@@ -1,7 +1,7 @@
 #!/bin/sh
 set -eu
 
-mkdir install
+mkdir -p install/bin
 
 # extract the exec jar
 cd install && jar xf ../target/*-exec.jar

docker/bin/install-java-example

@@ -1,6 +1,8 @@
 #!/bin/sh
 set -eu
 
+mkdir -p install/bin
+
 # Copy dependencies and compiled classes
 mvn -q --batch-mode dependency:copy-dependencies -DoutputDirectory=install/lib
 cp -r target/classes install/

docker/bin/install-jetty-example

@@ -2,7 +2,7 @@
 
 set -eu
 
-mkdir install
+mkdir -p install/bin
 
 # extract the war under /root
 cp -r target/*-SNAPSHOT install/root

docker/bin/start-boot-example

@@ -1,28 +1,8 @@
-#!/bin/sh
-
-set -eu
-
-case "$1" in
-  f|frontend|Frontend )
-    CLASS_NAME=Frontend
-    PORT=8081
-    ;;
-  b|backend|Backend )
-    CLASS_NAME=Backend
-    PORT=9000
-    ;;
-  * )
-    echo "Invalid argument: specify frontend or backend"
-    exit 1
-esac
-
-# write the docker-healthcheck url to a file
-IP="$(hostname -i || echo '127.0.0.1')"
-echo http://${IP}:${PORT}/health > health_url
+JAVA_OPTS=${JAVA_OPTS:-"-Xms32m -Xmx64m -XX:+ExitOnOutOfMemoryError"}
 
 exec java ${JAVA_OPTS} -cp . \
   -Dzipkin.endpoint=${ZIPKIN_ENDPOINT:=http://zipkin:9411/api/v2/spans} \
   -Dzipkin.supportsJoin=${ZIPKIN_SUPPORTS_JOIN:=true} \
   -Dbackend.endpoint=${BACKEND_ENDPOINT:=http://backend:9000/api} \
-  -Dloader.main=brave.webmvc.${CLASS_NAME} org.springframework.boot.loader.PropertiesLauncher \
-  --server.port=${PORT}
+  -Dloader.main=brave.webmvc.$(echo "${ZIPKIN_SERVICE}" | sed 's/.*/\u&/') \
+   org.springframework.boot.loader.PropertiesLauncher --server.port=${PORT}

docker/bin/start-example-header

@@ -0,0 +1,21 @@
+#!/bin/sh
+
+set -eu
+
+case "$1" in
+  frontend )
+    ZIPKIN_SERVICE=frontend
+    PORT=8081
+    ;;
+  backend )
+    ZIPKIN_SERVICE=backend
+    PORT=9000
+    ;;
+  * )
+    echo "Invalid argument: specify frontend or backend"
+    exit 1
+esac
+
+# write the docker-healthcheck url to a file
+IP="$(hostname -i || echo '127.0.0.1')"
+echo http://${IP}:${PORT}/health > health_url