Demo Ideas

This project is a Docker demo with two containers. The first is seq_http, a tiny HTTP service (https://github.com/aslag/seq_http). seq_test is a container that compiles the HTTP performance testing tool wrk (https://github.com/wg/wrk/). After you set up the two containers, you can run start the seq_http test environment and run benchmarks using seq_test. One benchmark script uses wrks LUA script feature.

If you want to investigate seq_http as a dev environment, see the section Dev Environment Tryout.

For more information on Docker, see http://docs.docker.io/en/latest/.

Docker Installation

For Ubuntu, see http://docs.docker.io/en/latest/installation/ubuntulinux/. If this seems cumbersome, consider using a Digital Ocean droplet to try docker (https://www.digitalocean.com/community/articles/how-to-use-the-digitalocean-docker-application). Digital Ocean's droplets are virtual machines you can easily create and destroy for such trial projects. The cost is minimal and the service is excellent.

Container Setup

Build each container:

docker build --rm -t aslag/seq_http:vanilla seq_http/.

docker build --rm -t aslag/seq_test seq_test/.

Basic Demo

Start the seq_http container in daemon mode:

docker run -d --name seq_http aslag/seq_http:vanilla

Execute benchmark scripts from the seq_test container:

docker run --rm -i -t --link seq_http:service aslag/seq_test /benchmark_scripts/fib.sh 1 10 20

docker run --rm -i -t --link seq_http:service aslag/seq_test /benchmark_scripts/count.sh 2 12 60

The benchmark scripts take args: num_of_threads num_of_concurrent_connections test_duration. These correspond to wrks' -t -c and -d (in seconds)

Dev Environment Tryout

Container Customization

(optional) Given server ssh keys in ~/.ssh/servers/testo/, execute the following to customize the container and re-tag it aslag/seq_http:vanilla (note that if you have a running instance of aslag/seq_http:vanilla, you must stop and remove it first):

tar -cf - -C ~/.ssh/servers/testo/ . | docker run -i aslag/seq_http:vanilla sh -c '(cd /etc/ssh/ && tar -xpf -)' && (CID=$( docker ps -a | grep 'aslag/seq_http' | cut -d' ' -f1 ); docker commit $CID aslag/seq_http:vanilla; docker rm $CID )

(optional) Given a client ssh pubkey in ~/.ssh/id_rsa.pub, execute the following to customize the container and tag it aslag/seq_http:mykey:

cat ~/.ssh/id_rsa.pub | docker run -i aslag/seq_http:vanilla sh -c 'cat > /root/.ssh/authorized_keys && chmod 600 /root/.ssh/authorized_keys' && (CID=$( docker ps -a | grep 'aslag/seq_http' | cut -d' ' -f1 ); docker commit $CID aslag/seq_http:mykey; docker rm $CID )

Start seq_http docker container (this one assumes you've setup an SSH key and retagged the container) and invoke supervisord to start the ssh daemon:

docker run -d --name seq_http -p 3000:3000 -p 3322:22 aslag/seq_http:mykey /usr/bin/supervisord -n -c /etc/supervisor/supervisord.conf

Note the use of the '-p' switch. This forwards the host's port before the colon (3322 in one case) to the port 22 inside the container.

Note also that if you haven't set up keys (the optional steps), you'll need to use the root password to login as root over SSH. The root password is 'testo'.

Workstation Setup

cd ~/projects && mkdir seq_http-CONTAINER
sshfs -o nonempty -o uid=$( id -u ),gid=$( id -g ) root@localhost:/seq_http seq_http-CONTAINER -p 3322

Warning: This sshfs command mounts the container's source dir for the project on your workstation. Any changes made in the source dir must be copied or committed before the dev container is restarted or those changes will be lost. Instructions on checking out source to your workstation and synchronizing filesystems are forthcoming.

Dev Workflow

SSH to the container:

ssh -oPort=3322 root@localhost

Start the dev server:

cd /seq_http && LEIN_ROOT=true lein ring server-headless 3000

Note that the app in the container is executed in development mode and will hot-reload source changes.

If you started the seq_http daemon with -p 3000:3000 (as mentioned above) traffic originating from the host system (your workstation, probably) will be forwarded to the dev container's server. You can test that with a command like this:

curl -i http://localhost:3000/api/count/5

Docker Common

See all containers (running and not):

docker ps -a

Stop and remove a container by ID:

docker stop <running_container_id> && docker rm $_

See all images:

docker images

Stop and remove an image:

docker rmi <image_id>

For more information about docker commands, see: http://docs.docker.io/en/latest/reference/commandline/

Notes

• seq_http's openjdk-7-jdk depends on lots of graphical and other packages we don't need. In a local environment, it'd make sense to host a copy of a JDK and have the docker container download that rather than using the OS's package.

• Docker doesn't download packages from the net as fast as a native Linux box or SmartOS VMs do. This really doesn't matter because Docker images are built infrequently and it aggressively caches. To make use of the caching, start the seq_test build command after the seq_http build command has finished updating debian.

• I use supervisord to start the SSH service in the seq_http container when used as a dev environment. This can easily be added-to with other persistent services.

Known Issues

• The SSHFS mount doesn't create a natural way to work with a project's source. It'd be better to use an intelligent FS synchronizing scheme that would synchronize source trees between the container and the host. It should ignore copying binaries and other artifacts that might be in the project dir.

• This sample hard-codes some config information (like the port 3000 used by seq_http). It is probably desirable to make this a configuration option.

• The SSH key setup procedure is a bit crufty and the details could be hidden in a script that does condition checking before executing. Fix that.