Python Web应用

The goal of this example is to show you how you can author your own Docker images using a parent image, making changes to it, and then saving the results as a new image. We will do that by making a simple hello Flask web application image.

Steps:

sudo docker pull shykes/pybuilder

We are downloading the shykes/pybuilder Docker image

URL=http://github.com/shykes/helloflask/archive/master.tar.gz

We set a URL variable that points to a tarball of a simple helloflask web app

BUILD_JOB=$(sudo docker run -d -t shykes/pybuilder:latest /usr/local/bin/buildapp $URL)

Inside of the shykes/pybuilder image there is a command called buildapp, we are running that command and passing the $URL variable from step 2 to it, and running the whole thing inside of a new container. The BUILD_JOB environment variable will be set with the new container ID.

sudo docker attach -sig-proxy=false $BUILD_JOB
[...]

While this container is running, we can attach to the new container to see what is going on. The flag --sig-proxy set as false allows you to connect and disconnect (Ctrl-C) to it without stopping the container.

sudo docker ps -a

List all Docker containers. If this container has already finished running, it will still be listed here.

BUILD_IMG=$(sudo docker commit $BUILD_JOB _/builds/github.com/shykes/helloflask/master)

Save the changes we just made in the container to a new image called _/builds/github.com/hykes/helloflask/master and save the image ID in the BUILD_IMG variable name.

WEB_WORKER=$(sudo docker run -d -p 5000 $BUILD_IMG /usr/local/bin/runapp)

• “docker run -d “ run a command in a new container. We pass “-d” so it runs as a daemon.
• “-p 5000” the web app is going to listen on this port, so it must be mapped from the container to the host system.
• “$BUILD_IMG” is the image we want to run the command inside of.
• /usr/local/bin/runapp is the command which starts the web app.

Use the new image we just created and create a new container with network port 5000, and return the container ID and store in the WEB_WORKER variable.

sudo docker logs $WEB_WORKER
 * Running on http://0.0.0.0:5000/

View the logs for the new container using the WEB_WORKER variable, and if everything worked as planned you should see the line Running on http://0.0.0.0:5000/ in the log output.

WEB_PORT=$(sudo docker port $WEB_WORKER 5000 | awk -F: '{ print $2 }')

Look up the public-facing port which is NAT-ed. Find the private port used by the container and store it inside of the WEB_PORT variable.

# install curl if necessary, then ...
curl http://127.0.0.1:$WEB_PORT
  Hello world!

Access the web app using the curl binary. If everything worked as planned you should see the line Hello world! inside of your console.

Video:

See the example in action

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