Docker on Ubuntu

java_oom.md

Determine whether cgroups limit the available memory

• Create Dockerfile for test

FROM ubuntu:16.04

RUN apt-get update && \
    apt-get install -y openjdk-8-jdk && \
    rm -rf /var/lib/apt/list/*

CMD ["/bin/bash"]

• Build image

docker build -t j8 .

• Run with memory constraint:

docker run -it -m 521m --name=java8 j8

• Check usable memory:

$ free -h
              total        used        free      shared  buff/cache   available
Mem:           1.9G        161M        950M        153M        868M        1.4G
Swap:          3.8G          0B        3.8G
$ java -XX:+PrintFlagsFinal -version | grep -i heapsize | egrep 'Initial|Max'
openjdk version "1.8.0_121"
OpenJDK Runtime Environment (build 1.8.0_121-8u121-b13-0ubuntu1.16.04.2-b13)
OpenJDK 64-Bit Server VM (build 25.121-b13, mixed mode)
    uintx InitialHeapSize                          := 33554432                            {product}
    uintx MaxHeapSize                              := 520093696                           {product}

• Run with other memory constraint:

docker rm j8
docker run -it -m 1024m --name=java8 j8

• Check usable memory

$ free -h
              total        used        free      shared  buff/cache   available
Mem:           1.9G        162M        949M        153M        867M        1.4G
Swap:          3.8G          0B        3.8G
$ java -XX:+PrintFlagsFinal -version | grep -i heapsize | egrep 'Initial|Max'
openjdk version "1.8.0_121"
OpenJDK Runtime Environment (build 1.8.0_121-8u121-b13-0ubuntu1.16.04.2-b13)
OpenJDK 64-Bit Server VM (build 25.121-b13, mixed mode)
    uintx InitialHeapSize                          := 33554432                            {product}
    uintx MaxHeapSize                              := 520093696                           {product}

Sources

• https://dzone.com/articles/java-and-memory-limits-in-containers-lxc-docker-an

notes.md

Installing Docker on Ubuntu

Docker install

• Remove old versions

sudo apt-get remove docker docker-engine

• Add docker repositories:
  • Required packages:

  sudo apt-get install \
      apt-transport-https \
      ca-certificates \
      curl \
      software-properties-common

  • Docker's GPG key (validate: sudo apt-key fingerprint 0EBFCD88 should be 9DC8 5822 9FC7 DD38 854A E2D8 8D81 803C 0EBF CD88):

  curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -

  • amd64 repository

  sudo add-apt-repository \
   "deb [arch=amd64] https://download.docker.com/linux/ubuntu \
   $(lsb_release -cs) \
   stable"

• Install

sudo apt-get update
sudo apt-get install docker-ce

Enable "sudoless" docker

sudo groupadd docker
sudo gpasswd -a ${USER} docker # where ${USER} is the username
sudo service docker restart
newgrp docker

Sources

• https://docs.docker.com/engine/installation/linux/ubuntu/
• https://askubuntu.com/questions/477551/how-can-i-use-docker-without-sudo