35 lines
1.9 KiB
Markdown
35 lines
1.9 KiB
Markdown
# Bundle Container Format
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This section defines a format for encoding a container as a *bundle* - a directory organized in a certain way, and containing all the necessary data and metadata for any compliant runtime to perform all standard operations against it.
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See also [OS X application bundles](http://en.wikipedia.org/wiki/Bundle_%28OS_X%29) for a similar use of the term *bundle*.
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The format does not define distribution.
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In other words, it only specifies how a container must be stored on a local filesystem, for consumption by a runtime.
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It does not specify how to transfer a container between computers, how to discover containers, or assign names or versions to them.
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Any distribution method capable of preserving the original layout of a container, as specified here, is considered compliant.
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A standard container bundle is made of the following 3 parts:
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- A top-level directory holding everything else
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- One or more content directories
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- A configuration file
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# Directory layout
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A Standard Container bundle is a directory containing all the content needed to load and run a container.
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This includes two configuration files `config.json` and `runtime.json`, and a rootfs directory.
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The `config.json` file contains settings that are host independent and application specific such as security permissions, environment variables and arguments.
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The `runtime.json` file contains settings that are host specific such as memory limits, local device access and mount points.
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The goal is that the bundle can be moved as a unit to another machine and run the same application if `runtime.json` is removed or reconfigured.
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The syntax and semantics for `config.json` are described in [this specification](config.md).
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A single `rootfs` directory MUST be in the same directory as the `config.json`.
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The names of the directories may be arbitrary, but users should consider using conventional names as in the example below.
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```
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config.json
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runtime.json
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rootfs/
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```
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