3036b5a196
Docker-DCO-1.1-Signed-off-by: Sven Dowideit <SvenDowideit@home.org.au> (github: SvenDowideit)
120 lines
4.1 KiB
ReStructuredText
120 lines
4.1 KiB
ReStructuredText
:title: Python Web app example
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:description: Building your own python web app using docker
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:keywords: docker, example, python, web app
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.. _python_web_app:
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Python Web App
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==============
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.. include:: example_header.inc
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While using Dockerfiles is the prefered way to create maintainable
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and repeatable images, its useful to know how you can try things out
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and then commit your live changes to an image.
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The goal of this example is to show you how you can modify your own
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Docker images by making changes to a running
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container, and then saving the results as a new image. We will do
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that by making a simple 'hello world' Flask web application image.
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**Steps:**
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.. code-block:: bash
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$ sudo docker pull shykes/pybuilder
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Download the ``shykes/pybuilder`` Docker image from the ``http://index.docker.io``
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registry. Note that this container was built with a very old version of docker
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(May 2013), but can still be used now.
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.. code-block:: bash
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$ sudo docker run -i -t -name pybuilder_run shykes/pybuilder bash
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$$ URL=http://github.com/shykes/helloflask/archive/master.tar.gz
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$$ /usr/local/bin/buildapp $URL
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[lots of output later]
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$$ exit
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We then start a new container running interactively using the
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image.
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First, we set a ``URL`` variable that points to a tarball of a simple
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helloflask web app, and then we run a command contained in the image called
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``buildapp``, passing it the ``$URL`` variable. The container is
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given a name ``pybuilder_run`` which we will use in the next steps.
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While this example is simple, you could run any number of interactive commands,
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try things out, and then exit when you're done.
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.. code-block:: bash
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$ sudo docker commit pybuilder_run /builds/github.com/shykes/helloflask/master
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c8b2e8228f11b8b3e492cbf9a49923ae66496230056d61e07880dc74c5f495f9
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Save the changes we just made in the container to a new image called
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``/builds/github.com/hykes/helloflask/master``. You now have 3 different
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ways to refer to the container, name, short-id ``c8b2e8228f11``, or
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long-id ``c8b2e8228f11b8b3e492cbf9a49923ae66496230056d61e07880dc74c5f495f9``.
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.. code-block:: bash
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$ WEB_WORKER=$(sudo docker run -d -p 5000 /builds/github.com/hykes/helloflask/master /usr/local/bin/runapp)
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Use the new image to create a new container with
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network port 5000, and return the container ID and store in the
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``WEB_WORKER`` variable (rather than naming a container/image, you can use the ID's).
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- **"docker run -d "** run a command in a new container. We pass "-d"
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so it runs as a daemon.
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- **"-p 5000"** the web app is going to listen on this port, so it
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must be mapped from the container to the host system.
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- **/usr/local/bin/runapp** is the command which starts the web app.
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.. code-block:: bash
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$ sudo docker logs -f $WEB_WORKER
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* Running on http://0.0.0.0:5000/
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View the logs for the new container using the ``WEB_WORKER`` variable, and
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if everything worked as planned you should see the line ``Running on
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http://0.0.0.0:5000/`` in the log output.
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To exit the view without stopping the container, hit Ctrl-C, or open another
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terminal and continue with the example while watching the result in the logs.
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.. code-block:: bash
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$ WEB_PORT=$(sudo docker port $WEB_WORKER 5000 | awk -F: '{ print $2 }')
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Look up the public-facing port which is NAT-ed. Find the private port
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used by the container and store it inside of the ``WEB_PORT`` variable.
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.. code-block:: bash
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# install curl if necessary, then ...
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$ curl http://127.0.0.1:$WEB_PORT
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Hello world!
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Access the web app using the ``curl`` binary. If everything worked as planned you
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should see the line ``Hello world!`` inside of your console.
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.. code-block:: bash
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$ sudo docker ps --all
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List ``--all`` the Docker containers. If this container had already finished
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running, it will still be listed here with a status of 'Exit 0'.
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.. code-block:: bash
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$ sudo docker stop $WEB_WORKER
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$ sudo docker rm $WEB_WORKER pybuilder_run
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$ sudo docker rmi /builds/github.com/shykes/helloflask/master shykes/pybuilder:latest
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And now stop the running web worker, and delete the containers, so that we can
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then delete the images that we used.
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