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Merge pull request #32735 from bhavin192/patch-1

Add note about host-dir in VOLUME
(cherry picked from commit f2fff9d913a8ab0436dd56033189a7c3713a59a2)
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

Sebastiaan van Stijn authored on 2017/04/26 02:18:16
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@@ -1281,18 +1281,28 @@ This Dockerfile results in an image that causes `docker run`, to
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 create a new mount point at `/myvol` and copy the  `greeting` file
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 into the newly created volume.
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-> **Note**:
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-> When using Windows-based containers, the destination of a volume inside the
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-> container must be one of: a non-existing or empty directory; or a drive other
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-> than C:.
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+### Notes about specifying volumes
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-> **Note**:
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-> If any build steps change the data within the volume after it has been
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-> declared, those changes will be discarded.
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+Keep the following things in mind about volumes in the `Dockerfile`.
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-> **Note**:
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-> The list is parsed as a JSON array, which means that
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-> you must use double-quotes (") around words not single-quotes (').
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+- **Volumes on Windows-based containers**: When using Windows-based containers,
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+  the destination of a volume inside the container must be one of:
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+  
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+  - a non-existing or empty directory
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+  - a drive other than `C:`
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+
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+- **Changing the volume from within the Dockerfile**: If any build steps change the
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+  data within the volume after it has been declared, those changes will be discarded.
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+
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+- **JSON formatting**: The list is parsed as a JSON array.
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+  You must enclose words with double quotes (`"`)rather than single quotes (`'`).
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+
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+- **The host directory is declared at container run-time**: The host directory
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+  (the mountpoint) is, by its nature, host-dependent. This is to preserve image
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+  portability. since a given host directory can't be guaranteed to be available
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+  on all hosts.For this reason, you can't mount a host directory from
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+  within the Dockerfile. The `VOLUME` instruction does not support specifying a `host-dir`
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+  parameter.  You must specify the mountpoint when you create or run the container.
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 ## USER
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