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docs/content-flow: update the description of the content labels

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Signed-off-by: Iceber Gu <wei.cai-nat@daocloud.io>
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Iceber Gu
2023-01-05 14:03:31 +08:00
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@@ -254,9 +254,21 @@ sha256:1ed3521a5dcbd05214eb7f35b952ecf018d5a6610c32ba4e315028c556f45e94 1.732kB
#### Labels
Note that each chunk of content has several labels on it. This sub-section describes the labels.
Note that each blob of content has several labels on it. This sub-section describes the labels.
This is not intended to be a comprehensive overview of labels.
#### Common Labels
For images pulled from remotes, the `containerd.io.distribution.source.<registry>=[<repo/1>,<repo/2>]` label
is added to each blob of the image to indicate its source.
```
containerd.io/distribution.source.docker.io=library/redis
```
If the blob is shared by different repos in the same registry, the repo name will be appended:
```
containerd.io/distribution.source.docker.io=library/redis,myrepo/redis
```
##### Layer Labels
We start with the layers themselves. These have only one label: `containerd.io/uncompressed`. These files are
@@ -294,7 +306,9 @@ This is used to connect this config to a snapshot. We will look at that shortly
The labels on the manifest also begin with `containerd.io/gc.ref`, indicating that they are used to control
garbage collection. A manifest has several "children". These normally are the config and the layers. We want
to ensure that as long as the image remains around, i.e. the manifest, the children do not get garbage collected.
Thus, we have labels referencing each child, `containerd.io/gc.ref.content.<index>`.
Thus, we have labels referencing each child:
* `containerd.io/gc.ref.content.config` references the config
* `containerd.io/gc.ref.content.l.<index>` reference the layers
In our example, the manifest is `sha256:9bb13890319dc01e5f8a4d3d0c4c72685654d682d568350fd38a02b1d70aee6b`, and the labels are as follows.
@@ -315,7 +329,7 @@ These are precisely those children of the manifest - the config and layers - tha
The labels on the index also begin with `containerd.io/gc.ref`, indicating that they are used to control
garbage collection. An index has several "children", i.e. the manifests, one for each platform, as discussed above.
We want to ensure that as long as the index remains around, the children do not get garbage collected.
Thus, we have labels referencing each child, `containerd.io/gc.ref.content.<index>`.
Thus, we have labels referencing each child, `containerd.io/gc.ref.content.m.<index>`.
In our example, the index is `sha256:2a9865e55c37293b71df051922022898d8e4ec0f579c9b53a0caee1b170bc81c`, and the labels are as follows: