EUReKA (Dependencies Management & Direct Access to Containers)

/!\ Work still in progress

Provides a solution to Proposal: Use Swarm place holders to supply target host and port to Docker run #1106 & related issues, also to Missing Depends_ON functionality during start process within docker-swarm #31333.

The EUReKA Server

Start

To run it:

docker run --rm -v /var/run/docker.sock:/var/run/docker.sock -p 5000:5000 -e FLASK_DEBUG=1 logimethods/eureka

or, as a service

docker service create --network ${network} --constraint=node.role==manager --name eureka --mount type=bind,source=/var/run/docker.sock,destination=/var/run/docker.sock -p 5000:5000 -e FLASK_DEBUG=0 logimethods/eureka

Usage

As a service

curl http://localhost:5000/container/id/<name>
curl http://localhost:5000/service/id/<string:node>/<string:name>
curl http://localhost:5000/services/node/<string:node>
curl http://localhost:5000/services

Note: <name> can be a Python Regex: https://docs.python.org/3.6/library/re.html

Through a Container (that needs to be extended)

docker run --rm --network ${network} --name entrypoint --constraint=node.role!=manager -e NODE_ID={{.Node.ID}} -e EUREKA_LINE_START=">> " logimethods/eureka:entrypoint env

xxx_url -> the first URL
xxx_url0 -> all the URLs
xxx_url1 -> URL 1
xxx_url{n} -> URL {n}

DEPENDS_ON & WAIT_FOR

DEPENDS_ON

Is especting the targeted Container to answer on port ${EUREKA_AVAILABILITY_PORT} (by default 6868).

WAIT_FOR

Is especting the targeted Container to answer to the ping request.

READY_WHEN & FAILED_WHEN

READY_WHEN

Makes the Container Available when the provided string is catched on the log.

Tip: to be able to desable the ping answer of a container, the /proc:/writable-proc volume has to be set.

FAILED_WHEN

Makes the Container Unavailable when the provided string is catched on the log.

Note: If $KILL_WHEN_FAILED is set to true, the Caontainer will then be killed.

Docker HEALTHCHECK

To setup the Docker Health Check feature, you should add the following instruction to the Dockerfile:

HEALTHCHECK --interval=5s --timeout=1s --retries=1 CMD test -f /availability.lock

Usage

Note, first build the Docker Images:

> ./build_exp.sh

docker run / docker service

To build a "ping" Image:

pushd ping
docker build -t ping_container .
popd

Make sure that the Eureka Server is started, then run on two separate terminals

• the Container that is waiting

  docker run --rm -it --network ${network} --name ping -v /proc:/writable-proc -e DEPENDS_ON=eureka,ping0 -e WAIT_FOR=www.docker.com:80,eureka_local,ping0 -e SETUP_LOCAL_CONTAINERS=true -e CHECK_TIMEOUT=25 ping_container ping eureka_local
  

• The Container that is expected

  docker run --rm -it --network ${network} --name ping0 --sysctl net.ipv4.icmp_echo_ignore_all=1 -v /proc:/writable-proc -e READY_WHEN="seq=5" -e FAILED_WHEN="seq=20" -e KILL_WHEN_FAILED=true ping_container ping www.docker.com
  

  or, as a service

  docker run --rm -it --network ${network} --name ping0 --mount type=bind,source=/proc,destination=/writable-proc -e READY_WHEN="seq=5" -e FAILED_WHEN="seq=20" -e KILL_WHEN_FAILED=true ping_container ping www.docker.com
  

docker stack

docker stack deploy -c docker-compose.yml test

Setup of the Dockerfile

• Alpine, see https://github.com/Logimethods/docker-eureka/blob/master/ping_alpine_exp/Dockerfile
• Ubuntu, see https://github.com/Logimethods/docker-eureka/blob/master/ping_ubuntu_exp/Dockerfile
• Debian, see https://github.com/Logimethods/docker-eureka/blob/master/ping_debian_exp/Dockerfile

References to EUReKA

• https://github.com/Logimethods/smart-meter/tree/multi-stage-build

New features (?)

EXPERIMENTAL & DEV REFERENCES

• https://stackoverflow.com/questions/26177059/refresh-net-core-somaxcomm-or-any-sysctl-property-for-docker-containers/26197875#26197875
• https://stackoverflow.com/questions/26050899/how-to-mount-host-volumes-into-docker-containers-in-dockerfile-during-build

-e CHECK_DEPENDENCIES_INTERVAL=5

docker run --rm -it --network ${network} logimethods/eureka:ping

entrypoint.sh MERGING

COPY --from=entrypoint eureka_utils.sh /eureka_utils.sh
COPY --from=entrypoint entrypoint.sh /entrypoint.sh
RUN head -n -1 /docker-entrypoint.sh > /merged_entrypoint.sh ; \
    tail -n +3  /entrypoint.sh >> /merged_entrypoint.sh \
    chmod +x /merged_entrypoint.sh
## RUN cat /merged_entrypoint.sh

https://github.com/docker/swarm/issues/1106

Waiting for Multi-Stage builds on docker hub