Docker

install

https://allysonjulian.com/posts/setting-up-docker-with-xhyve/

https://docs.docker.com/v17.12/docker-for-mac/install/#download-docker-for-mac

brew update
brew install docker docker-compose docker-machine

xhyve

deprecated, use hyperkit

docker-machine-driver-xhyve

docker-machine env dev

hyperkit

https://github.com/kubernetes/minikube/blob/master/docs/drivers.md#hyperkit-driver

curl -LO https://storage.googleapis.com/minikube/releases/latest/docker-machine-driver-hyperkit \
&& sudo install -o root -g wheel -m 4755 docker-machine-driver-hyperkit /usr/local/bin/

or

docker-machine-driver-hyperkit
docker-machine create dev --driver hyperkit

Docker

docker exec -it vibrant_bell sh

run shell on container vibrant_bell

Healthchecks

documentation: https://docs.docker.com/engine/reference/builder/#healthcheck

https://ryaneschinger.com/blog/using-docker-native-health-checks/

health check samples: https://github.com/docker-library/healthcheck

Startup dependencies

https://docs.docker.com/compose/startup-order/

compose / stack

compose is legacy

links are legacy.

docker container run --name api-gateway --rm --link config-service:ali-config-service api-gateway:latest

start stack

docker stack deploy -c docker-compose.yml javelin

ENV vars

how entry points work: https://stackoverflow.com/questions/41512237/how-to-execute-a-shell-command-before-the-entrypoint-via-the-dockerfile

vars in dockerfile: https://stackoverflow.com/questions/19537645/get-environment-variable-value-in-dockerfile

environment replacement doc: https://docs.docker.com/engine/reference/builder/#environment-replacement

how to run command to set env var

1. Create dockerrun.sh script to set as entry point with the following

   GATEWAY=$(ip route show 0.0.0.0/0 dev eth0 | cut -d\  -f3)
   SPRING_CONFIG_URI=http://$GATEWAY:8888
   java $JAVA_OPTS -DSPRING_CONFIG_URI=$SPRING_CONFIG_URI -Djava.security.egd=file:/dev/./urandom -Dserver.port=8081 -jar /app.jar
   

2. edit Dockerfile

   FROM openjdk:8-jdk-alpine
   VOLUME /tmp
   EXPOSE 8081
   COPY target/dockerrun.sh /
   ADD target/api-gateway.jar app.jar
   ENV JAVA_OPTS=""
   ENTRYPOINT exec sh ./dockerrun.sh
   

Networking

docs: https://docs.docker.com/engine/userguide/networking/work-with-networks/#basic-container-networking-example

get container ip

hostname -i

get container gateway

$(ip route show 0.0.0.0/0 dev eth0 | cut -d\  -f3)

or

ip route|awk '/default/ { print $3 }'

** Use docker compose/stacks to network containers. old way was link. using the gateway address will also do it.

tutorials

getting started for java: https://github.com/docker/labs/tree/master/developer-tools/java/

getting started for spring boot: https://spring.io/guides/gs/spring-boot-docker/

host multiple websites on single host docker: https://blog.florianlopes.io/host-multiple-websites-on-single-host-docker/

nginx template vars: https://docs.docker.com/samples/library/nginx/#using-environment-variables-in-nginx-configuration

phantomjs

http://fabiorehm.com/blog/2015/07/22/building-a-minimum-viable-phantomjs-2-docker-image/

alpine linux won't build phantom:

https://github.com/Overbryd/docker-phantomjs-alpine

Playground

http://play-with-docker.com

Volumes

• mount points are owned by root, may have implications when mounting user home
  • create a VOLUME and run ls -la /home
  • add a volume at run to /home/username and run ls -la /home to see diff
  • paths on host must be absolute.
  • non-existent paths are created

Mac OS

https://docs.docker.com/docker-for-mac/osxfs/#namespaces

Alpine linux

docs: https://docs.docker.com/samples/library/alpine/

creating users: https://github.com/mhart/alpine-node/issues/48

RUN addgroup -g 1000 -S username && \
    adduser -u 1000 -S username -G username

montoring

http://fuzzyblog.io/blog/docker/2017/06/25/docker-tutorial-understanding-container-memory-usage.html

https://dzone.com/articles/monitoring-docker-containers-docker-stats-cadvisor-1 - breakdown of four types of monitoring including: stats, cadvisor, remote api, and universal control plane

docker stats

is a live 1sec view that streams

docker stats

docker remote api

https://docs.docker.com/develop/sdk/ - sdk for interacting

https://docs.docker.com/engine/api/v1.37/ - api docs

using cAdvisor

This will run in a docker container and expose a web view at: localhost:8080

#!/usr/bin/env bash
docker run -d --name=cadvisor \
    -p 8081:8080 \
    --volume=/var/run:/var/run:rw \
    --volume=/sys:/sys:ro \
    --volume=/var/lib/docker/:/var/lib/docker:ro \
    google/cadvisor:latest

Gives you host and container metrics such as:

Can be used with other tools for storage and retrieval. docs: https://github.com/google/cadvisor/blob/master/docs/storage/README.md

Caching/Layers

https://thenewstack.io/understanding-the-docker-cache-for-faster-builds/

https://docs.docker.com/develop/develop-images/dockerfile_best-practices/#run

brute force: –no-cache during build

use multi-stage builds and separate layers correctly

fix terminal size

fix issue where terminal has wierd wraps

docker exec -e COLUMNS="`tput cols`" -e LINES="`tput lines`" -ti mycontainer bash

interactive experimenting

run an alipine linux container in interactive shell

docker run -it alpine:3.9 /bin/bash