73 lines
3.5 KiB
Markdown
73 lines
3.5 KiB
Markdown
---
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description: Explains what the Registry is, basic use cases and requirements
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keywords: registry, on-prem, images, tags, repository, distribution, use cases, requirements
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title: About Registry
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---
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A registry is a storage and content delivery system, holding named container
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images and other content, available in different tagged versions.
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> Example: the image `distribution/registry`, with tags `2.0` and `2.1`.
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Users interact with a registry by pushing and pulling images.
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> Example: `docker pull registry-1.docker.io/distribution/registry:2.1`.
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Storage itself is delegated to drivers. The default storage driver is the local
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posix filesystem, which is suitable for development or small deployments.
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Additional cloud-based storage drivers like S3, Microsoft Azure and Google Cloud Storage
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are supported. People looking into using other storage drivers should consider if
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the driver they'd like to be supported is S3 compatible like many cloud storage systems
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as adding new storage driver support has been put on hold for the time being.
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Since securing access to your hosted images is paramount, the Registry natively
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supports TLS and basic authentication.
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The Registry GitHub repository includes additional information about advanced
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authentication and authorization methods. Only very large or public deployments
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are expected to extend the Registry in this way.
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Finally, the Registry ships with a robust [notification system](notifications),
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calling webhooks in response to activity, and both extensive logging and reporting,
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mostly useful for large installations that want to collect metrics.
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## Understanding image naming
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Image names as used in typical docker commands reflect their origin:
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* `docker pull ubuntu` instructs docker to pull an image named `ubuntu` from Docker Hub. This is simply a shortcut for the longer `docker pull docker.io/library/ubuntu` command
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* `docker pull myregistrydomain:port/foo/bar` instructs docker to contact the registry located at `myregistrydomain:port` to find the image `foo/bar`
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You can find out more about the various Docker commands dealing with images in
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the [Docker engine documentation](https://docs.docker.com/engine/reference/commandline/cli/).
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## Use cases
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Running your own Registry is a great solution to integrate with and complement
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your CI/CD system. In a typical workflow, a commit to your source revision
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control system would trigger a build on your CI system, which would then push a
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new image to your Registry if the build is successful. A notification from the
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Registry would then trigger a deployment on a staging environment, or notify
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other systems that a new image is available.
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It's also an essential component if you want to quickly deploy a new image over
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a large cluster of machines.
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Finally, it's the best way to distribute images inside an isolated network.
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## Requirements
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You absolutely need to be familiar with Docker, specifically with regard to
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pushing and pulling images. You must understand the difference between the
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daemon and the cli, and at least grasp basic concepts about networking.
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Also, while just starting a registry is fairly easy, operating it in a
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production environment requires operational skills, just like any other service.
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You are expected to be familiar with systems availability and scalability,
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logging and log processing, systems monitoring, and security 101. Strong
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understanding of http and overall network communications, plus familiarity with
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golang are certainly useful as well for advanced operations or hacking.
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## Next
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Dive into [deploying your registry](deploying)
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