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Introduction to Docker

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The FROM Instruction

0:55 with Jay McGavren and Jared Smith

The FROM instruction must always be the first instruction in the Dockerfile. As an argument, you provide a name and an optional tag for an image that should be used as the base for your Docker container. You wouldn't want to build a host OS for your app from scratch, so the FROM instruction lets you simply use an image for Linux or another OS as your basis.

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    Now let's look closer at the Dockerfile we're using to build our Python web 0:00
    app's image. 0:04
    With the exception of setting environment variables, 0:05
    the FROM instruction must always be the first instruction in the Dockerfile. 0:07
    As an argument, you provide a name an optional tag for 0:12
    an image that should be used as the base for your docker container. 0:15
    You wouldn't wanna build a host OS for your app from scratch, so the FROM 0:19
    instruction lets you simply use an image for Linux or another OS as your basis. 0:22
    This instruction sets it up to use the latest version of the public Ubuntu image 0:28
    as a basis. 0:32
    Here's a different Dockerfile that creates an image with the Apache web server. 0:33
    This one is based on an image for Debian Linux instead of a Ubuntu, and 0:38
    it uses the stable tag instead of the latest tag. 0:42
    The Ubuntu and Debian images both give you stripped down Linux distributions. 0:45
    Each includes just enough functionality to be able to run 0:50
    most applications on top of. 0:53

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