42 lines
1.7 KiB
Markdown
42 lines
1.7 KiB
Markdown
<!--[metadata]>
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+++
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title = "Garbage Collection"
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description = "High level discussion of garabage collection"
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keywords = ["registry, garbage, images, tags, repository, distribution"]
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+++
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<![end-metadata]-->
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# What Garbage Collection Does
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"Garbage collection deletes blobs which no manifests reference. Manifests and
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blobs which are deleted by their digest through the Registry API will become
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eligible for garbage collection, but the actual blobs will not be removed from
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storage until garbage collection is run.
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# How Garbage Collection Works
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Garbage collection runs in two phases. First, in the 'mark' phase, the process
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scans all the manifests in the registry. From these manifests, it constructs a
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set of content address digests. This set is the 'mark set' and denotes the set
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of blobs to *not* delete. Secondly, in the 'sweep' phase, the process scans all
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the blobs and if a blob's content address digest is not in the mark set, the
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process will delete it.
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> **NOTE** You should ensure that the registry is in read-only mode or not running at
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> all. If you were to upload an image while garbage collection is running, there is the
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> risk that the image's layers will be mistakenly deleted, leading to a corrupted image.
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This type of garbage collection is known as stop-the-world garbage collection. In
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future registry versions the intention is that garbage collection will be an
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automated background action and this manual process will no longer apply.
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# How to Run
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You can run garbage collection by running
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`docker run --rm registry-image-name garbage-collect /etc/docker/registry/config.yml`
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Additionally, garbage collection can be run in `dry-run` mode, which will print
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the progress of the mark and sweep phases without removing any data.
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