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:title: Python Web app example
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:description: Building your own python web app using docker
:keywords: docker, example, python, web app
.. _python_web_app:
Building a python web app
=========================
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.. include :: example_header.inc
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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.
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**Steps:**
.. code-block :: bash
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docker pull shykes/pybuilder
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We are downloading the "shykes/pybuilder" docker image
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.. code-block :: bash
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URL=http://github.com/shykes/helloflask/archive/master.tar.gz
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We set a URL variable that points to a tarball of a simple helloflask web app
.. code-block :: bash
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BUILD_JOB=$(docker run -d -t shykes/pybuilder:latest /usr/local/bin/buildapp $URL)
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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. BUILD_JOB will be set with the new container_id.
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.. code-block :: bash
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docker attach $BUILD_JOB
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[...]
We attach to the new container to see what is going on. Ctrl-C to disconnect
.. code-block :: bash
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BUILD_IMG=$(docker commit $BUILD_JOB _/builds/github.com/hykes/helloflask/master)
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Save the changed we just made in the container to a new image called "_/builds/github.com/hykes/helloflask/master" and save the image id in the BUILD_IMG variable name.
.. code-block :: bash
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WEB_WORKER=$(docker run -d -p 5000 $BUILD_IMG /usr/local/bin/runapp)
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- **"docker run -d "** run a command in a new container. We pass "-d" so it runs as a daemon.
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- **"-p 5000"** the web app is going to listen on this port, so it must be mapped from the container to the host system.
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- **"$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.
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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.
.. code-block :: bash
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docker logs $WEB_WORKER
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* Running on \http://0.0.0.0:5000/
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view the logs for the new container using the WEB_WORKER variable, and if everything worked as planned you should see the line "Running on http://0.0.0.0:5000/" in the log output.
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.. code-block :: bash
WEB_PORT=$(docker port $WEB_WORKER 5000)
lookup the public-facing port which is NAT-ed store the private port used by the container and store it inside of the WEB_PORT variable.
.. code-block :: bash
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curl \http://`hostname` :$WEB_PORT
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Hello world!
access the web app using curl. If everything worked as planned you should see the line "Hello world!" inside of your console.
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**Video:**
See the example in action
.. raw :: html
<div style="margin-top:10px;">
<iframe width="720" height="350" src="http://ascii.io/a/2573/raw" frameborder="0"></iframe>
</div>
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Continue to :ref: `running_ssh_service` .