78 lines
2.7 KiB
Markdown
78 lines
2.7 KiB
Markdown
# container-copier: Copy files between volumes on change
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This repository contains a very simple tool called `container-copier` that will copy files from one
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location to another when the source file is changed. This tool uses [inotify] to receive
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notifications for when files are changed. This was developed to help me copy files between Docker
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volumes when they are changed.
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## Configuration
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The tool takes a TOML configuration file that specifies the files to copy. By default, the location
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of the file is expected to be `/config/container-copier.toml`, but this can be overriden with the
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`--config` argument or the `CONFIG` environment variable.
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The TOML configuration file specifies the files to copy as targets within a copyset (there can be
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any number of either):
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```toml
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# Each copyset assigns a name (for logging) and a parent 'source' and
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# 'target' directory.
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[[copysets]]
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name = "my_copyset"
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source = "/data/source"
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target = "/data/target"
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# Each target specifies the 'source' and 'target' paths, where 'source' is
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# the path to watch, and 'target' is the destination to copy to when changes
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# are detected.
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#
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# Both 'source' and 'target' are each appended to the 'source' and 'target'
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# fields in the copyset, respectively.
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[[copysets.targets]]
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# Watch for changes to: '/data/source/file-1.txt'
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source = "file-1.txt"
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# When changed, copy to: '/data/target/file-1.txt'
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target = "file-1.txt"
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```
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## Runnning
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You can run `container-copier` in Docker by using the [blakerain/container-copier] image from Docker
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Hub (or by building it yourself). For example:
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```
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docker run \
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-v config.toml:/config/container-copier.toml \
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-v source_volume:/data/source \
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-v target_volume:/data/target \
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blakerain/container-copier:latest
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```
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### Running as Root
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Currently the user that is specified in the Dockerfile is `1000`. For most intents and purposes this
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should be fine. However, there are cases where you will need `container-copier` to run as root to be
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able to access the contents of attached volumes. In which case, the user can be overridden with the
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`--user` argument to `docker run`. Note that the base image used is `scratch`, so there are no
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`/etc/passwd` entries (unless you add them). To use root you will need the numerical ID (UID) of the
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root user: 0:
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```
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docker run --user 0 \
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-v config.toml:/config/container-copier.toml \
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-v source_volume:/data/source \
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-v target_volume:/data/target \
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blakerain/container-copier:latest
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```
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## Restrictions
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There are currently a few restrictions:
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1. Each target must be a single file, there is no wildcard support (see #2).
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[inotify]: https://en.wikipedia.org/wiki/Inotify
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[blakerain/container-copier]: https://hub.docker.com/r/blakerain/container-copier
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