731e144a48
base_image_size effectively is the limit of a layer size that can be created using the devmapper snapshotter. While this will also depend on the thinpool size itself, something closer to the total image size (80%?) is more appropriate. As is, if you try to run an image like elastic, you'll need a much larger base_image_size than 128MB. Signed-off-by: Eric Ernst <eric.ernst@intel.com>
43 lines
1.4 KiB
Markdown
43 lines
1.4 KiB
Markdown
## Devmapper snapshotter
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Devmapper is a `containerd` snapshotter plugin that stores snapshots in ext4-formatted filesystem images
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in a devicemapper thin pool.
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## Setup
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To make it work you need to prepare `thin-pool` in advance and update containerd's configuration file.
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This file is typically located at `/etc/containerd/config.toml`.
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Here's minimal sample entry that can be made in the configuration file:
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```
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[plugins]
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...
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[plugins.devmapper]
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pool_name = "containerd-pool"
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base_image_size = "8192MB"
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...
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```
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The following configuration flags are supported:
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* `root_path` - a directory where the metadata will be available (if empty
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default location for `containerd` plugins will be used)
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* `pool_name` - a name to use for the devicemapper thin pool. Pool name
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should be the same as in `/dev/mapper/` directory
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* `base_image_size` - defines how much space to allocate when creating the base device
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Pool name and base image size are required snapshotter parameters.
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## Run
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Give it a try with the following commands:
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```bash
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ctr images pull --snapshotter devmapper docker.io/library/hello-world:latest
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ctr run --snapshotter devmapper docker.io/library/hello-world:latest test
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```
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## Requirements
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The devicemapper snapshotter requires `dmsetup` (>= 1.02.110) command line tool to be installed and
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available on your computer. On Ubuntu, it can be installed with `apt-get install dmsetup` command.
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