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basic-fullcycle-java17

README.md

Info

this is a replica of example project

it builds and runs java app in container started by docker-compose. The goal is to run java app as nonroot user and do not have any root ownerartifacts in the workspace after the completion

Prerequisites

if the docker-compose installed by apt-get it is too old. However it is OK to install docker-compose via apt-get first for dependency sake. NOTE: the download instruction from digitalocean modified to put the script into /usr/bin instead of /usr/local/bin

VERSION=2.14.0
sudo curl -sL https://github.com/docker/compose/releases/download/v$VERSION/docker-compose-`uname -s`-`uname -m` -o docker-compose
sudo chmod 775 docker-compose
sudo cp docker-compose /usr/bin/docker-compose

Usage

  • pull images
docker pull maven:3.8.3-openjdk-17
docker pull openjdk:17
docker pull openjdk:17-alpine3.14

it is over 1Gb worth of disk, counting build and run containers

maven            3.8.3-openjdk-17        0b9ddcb8259e   12 months ago   785MB
openjdk          17                      5e28ba2b4cdb   6 months ago    471MB
openjdk          17-alpine               264c9bdce361   17 months ago   326MB
  • build
./build.sh | tee build.log

this runs Dockerfile.build as non-root user to create the maven target directory in the project directory (does not like it to owned by the root user), followed by constructing a skeleton Java 17 container with similar non-root user to feed to docker-compose

  • create cluster
docker-compose up

this runs the java 17 app as docker-compose service mounted the current directory of workspace as applicaation writable /app dir.

  • interact with app
curl http://localhost:8585

check file attributes

stat *txt
  • if
Access: (0644/-rw-r--r--)  Uid: (    0/    root)   Gid: (    0/    root)

the docker is misconfigured

  • the expected is
access: (0644/-rw-r--r--)  Uid: ( 1000/sergueik)   Gid: ( 1000/sergueik)
  • interact with app running in alpine container
curl http://localhost:8586

the log will be created

Cleanup

docker-compose stop
docker-compose rm -f

the explicit image cleanup appears to be required:

 docker image ls | grep sample-java17| awk '{print $3}' | xargs -IX docker image rm X

NOTE

the /usr/local/bin/mvn-entrypoint.sh in the image maven:3.8.3-openjdk-17 is invoked and proudces the warning messages:

mkdir: cannot create directory ‘/root’: Permission denied

Can not write to /root/.m2/copy_reference_file.log. Wrong volume permissions? Carrying on ...
  • inspect the image
docker inspect maven:3.8.3-openjdk-17 | jq '.[]|.Config.Env'

[
  "PATH=/usr/java/openjdk-17/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin",
  "JAVA_HOME=/usr/java/openjdk-17",
  "LANG=C.UTF-8",
  "JAVA_VERSION=17.0.1",
  "MAVEN_HOME=/usr/share/maven",
  "MAVEN_CONFIG=/root/.m2"
]

 docker inspect maven:3.8.3-openjdk-17 | jq '.[]|.Config.Entrypoint'
[
  "/usr/local/bin/mvn-entrypoint.sh"
]

the build should normally be run by root, is is tweaked to have target mapped

TODO

update pom.xml and container configurations to have pinned jar name

<configuration>
  <finalName>${finalName}</finalName>
</configuration>

See Also

Author

Serguei Kouzmine