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@@ -9,7 +9,7 @@ Python Web App
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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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+While using Dockerfiles is the preffered 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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@@ -18,29 +18,29 @@ 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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-
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-.. code-block:: bash
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-
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- $ sudo docker pull shykes/pybuilder
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+Download the initial image
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+--------------------------
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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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+registry.
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+
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+This image contains a ``buildapp`` script to download the web app and then ``pip install``
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+any required modules, and a ``runapp`` script that finds the ``app.py`` and runs it.
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+.. _`shykes/pybuilder`: https://github.com/shykes/pybuilder
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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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+ $ sudo docker pull shykes/pybuilder
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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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- $$ exit
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+.. note:: This container was built with a very old version of docker
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+ (May 2013 - see `shykes/pybuilder`_ ), when the ``Dockerfile`` format was different,
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+ but the image can still be used now.
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+Interactively make some modifications
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+-------------------------------------
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-We then start a new container running interactively using the
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-image.
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+We then start a new container running interactively using the image.
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First, we set a ``URL`` variable that points to a tarball of a simple
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helloflask web app, and then we run a command contained in the image called
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``buildapp``, passing it the ``$URL`` variable. The container is
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@@ -51,8 +51,15 @@ try things out, and then exit when you're done.
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.. code-block:: bash
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- $ sudo docker commit pybuilder_run /builds/github.com/shykes/helloflask/master
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- c8b2e8228f11b8b3e492cbf9a49923ae66496230056d61e07880dc74c5f495f9
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+ $ sudo docker run -i -t -name pybuilder_run shykes/pybuilder bash
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+
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+ $$ URL=http://github.com/shykes/helloflask/archive/master.tar.gz
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+ $$ /usr/local/bin/buildapp $URL
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+ [...]
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+ $$ exit
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+
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+Commit the container to create a new image
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+------------------------------------------
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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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@@ -61,12 +68,22 @@ 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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+ $ sudo docker commit pybuilder_run /builds/github.com/shykes/helloflask/master
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+ c8b2e8228f11b8b3e492cbf9a49923ae66496230056d61e07880dc74c5f495f9
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+
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+
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+Run the new image to start the web worker
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+-----------------------------------------
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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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+.. code-block:: bash
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+
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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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+
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+
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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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@@ -74,10 +91,8 @@ network port 5000, and return the container ID and store in the
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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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-
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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 container logs
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+-----------------------
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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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@@ -88,19 +103,30 @@ 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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+ $ sudo docker logs -f $WEB_WORKER
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+ * Running on http://0.0.0.0:5000/
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+
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+
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+See the webapp output
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+---------------------
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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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+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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+
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.. code-block:: bash
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+ $ WEB_PORT=$(sudo docker port $WEB_WORKER 5000 | awk -F: '{ print $2 }')
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+
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# install curl if necessary, then ...
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$ 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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+
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+Clean up example containers and images
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+--------------------------------------
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.. code-block:: bash
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Sven Dowideit