mirror of https://github.com/docker/docs.git
88 lines
4.7 KiB
Markdown
88 lines
4.7 KiB
Markdown
---
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description: Learn about the architecture of Docker Trusted Registry.
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keywords:
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- docker, registry, dtr, architecture
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menu:
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main:
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identifier: dtr_architecture
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parent: workw_dtr
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weight: 20
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title: Architecture
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---
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# DTR architecture
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Docker Trusted Registry (DTR) is a Dockerized application that runs on a Docker
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Universal Control Plane cluster.
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## Containers
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When you install DTR on a node, the following containers are started:
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| Name | Description |
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|:---------------------------------|:----------------------------------------------------------------------------------------------------------------------------------|
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| dtr-nginx-<replica_id> | Receives http and https requests and proxies them to other DTR components. By default it listens to ports 80 and 443 of the host. |
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| dtr-api-<replica_id> | Executes the DTR business logic. It serves the DTR web application, and API. |
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| dtr-registry-<replica_id> | Implements the functionality for pulling and pushing Docker images. It also handles how images are stored. |
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| dtr-etcd-<replica_id> | A key-value store for persisting DTR configuration settings. Don't use it in your applications, since it's for internal use only. |
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| dtr-rethinkdb-<replica_id> | A database for persisting repository metadata. Don't use it in your applications, since it's for internal use only. |
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## Networks
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To allow containers to communicate, when installing DTR the following networks
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are created:
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| Name | Type | Description |
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|:-------|:--------|:--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
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| dtr-br | bridge | Allows containers on the same node to communicate with each other in a secure way. |
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| dtr-ol | overlay | Allows containers running on different nodes to communicate. This network is used in high-availability installations, to allow Etcd and RethinkDB containers to replicate their data. |
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The communication between all DTR components is secured using TLS. Also, when
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installing DTR, two Certificate Authorities (CAs) are created. These CAs are
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used to create the certificates used by Etcd and RethinkDB when communicating
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across nodes.
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## Volumes
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DTR uses these named volumes for persisting data:
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| Volume name | Location on host (/var/lib/docker/volumes/) | Description |
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|:--------------------------------|:--------------------------------------------|:-------------------------------------------------------------------------------------------------------------|
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| dtr-ca-<replica_id> | dtr-ca/_data | The volume where the private keys and certificates are stored so that containers can use TLS to communicate. |
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| dtr-etcd-<replica_id> | dtr-etcd/_data | The volume used by etcd to persist DTR configurations. |
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| dtr-registry-<replica_id> | dtr-registry/_data | The volume where images are stored, if DTR is configured to store images on the local filesystem. |
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| dtr-rethink-<replica_id> | dtr-rethink/_data | The volume used by RethinkDB to persist DTR data, like users and repositories. |
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If you don’t create these volumes, when installing DTR they are created with
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the default volume driver and flags.
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## Image storage
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By default, Docker Trusted Registry stores images on the filesystem of the host
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where it is running.
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You can also configure DTR to using these cloud storage backends:
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* Amazon S3
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* OpenStack Swift
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* Microsoft Azure
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For highly available installations, configure DTR to use a cloud storage
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backend or a network filesystem like NFS.
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## High-availability support
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For load balancing and high-availability, you can install multiple replicas of
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DTR, and join them to create a cluster.
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[Learn more about high availability](high-availability/index.md).
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## Where to go next
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* [System requirements](install/system-requirements.md)
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* [Install DTR](install/index.md)
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