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120 lines
4.1 KiB
Markdown
120 lines
4.1 KiB
Markdown
# Create registry mirror
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Although we now have shared storage for our persistent container data, our docker nodes don't share any other docker data, such as container images. This results in an inefficiency - every node which participates in the swarm will, at some point, need the docker image for every container deployed in the swarm.
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When dealing with large container (looking at you, GitLab!), this can result in several gigabytes of wasted bandwidth per-node, and long delays when restarting containers on an alternate node. (_It also wastes disk space on each node, but we'll get to that in the next section_)
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The solution is to run an official Docker registry container as a ["pull-through" cache, or "registry mirror"](https://docs.docker.com/registry/recipes/mirror/). By using our persistent storage for the registry cache, we can ensure we have a single copy of all the containers we've pulled at least once. After the first pull, any subsequent pulls from our nodes will use the cached version from our registry mirror. As a result, services are available more quickly when restarting container nodes, and we can be more aggressive about cleaning up unused containers on our nodes (more later)
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The registry mirror runs as a swarm stack, using a simple docker-compose.yml. Customize __your mirror FQDN__ below, so that Traefik will generate the appropriate LetsEncrypt certificates for it, and make it available via HTTPS.
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## Ingredients
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1. [Docker swarm cluster](/ha-docker-swarm/design/) with [persistent shared storage](/ha-docker-swarm/shared-storage-ceph.md)
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2. [Traefik](/ha-docker-swarm/traefik) configured per design
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3. DNS entry for the hostname you intend to use, pointed to your [keepalived](ha-docker-swarm/keepalived/) IP
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## Preparation
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Create /var/data/config/registry/registry.yml as follows:
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```
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version: "3"
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services:
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registry-mirror:
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image: registry:2
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networks:
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- traefik_public
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deploy:
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labels:
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- traefik.frontend.rule=Host:<your mirror FQDN>
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- traefik.docker.network=traefik_public
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- traefik.port=5000
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ports:
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- 5000:5000
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volumes:
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- /var/data/registry/registry-mirror-data:/var/lib/registry
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- /var/data/registry/registry-mirror-config.yml:/etc/docker/registry/config.yml
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networks:
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traefik_public:
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external: true
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```
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!!! note "Unencrypted registry"
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We create this registry without consideration for SSL, which will fail if we attempt to use the registry directly. However, we're going to use the HTTPS-proxied version via Traefik, leveraging Traefik to manage the LetsEncrypt certificates required.
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Create /var/data/registry/registry-mirror-config.yml as follows:
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```
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version: 0.1
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log:
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fields:
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service: registry
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storage:
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cache:
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blobdescriptor: inmemory
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filesystem:
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rootdirectory: /var/lib/registry
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delete:
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enabled: true
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http:
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addr: :5000
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headers:
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X-Content-Type-Options: [nosniff]
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health:
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storagedriver:
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enabled: true
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interval: 10s
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threshold: 3
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proxy:
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remoteurl: https://registry-1.docker.io
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```
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## Serving
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### Launch registry stack
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Launch the registry stack by running ```docker stack deploy registry -c <path-to-docker-compose.yml>```
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### Enable registry mirror and experimental features
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To tell docker to use the registry mirror, and (_while we're here_) in order to be able to watch the logs of any service from any manager node (_an experimental feature in the current Atomic docker build_), edit **/etc/docker-latest/daemon.json** on each node, and change from:
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```
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{
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"log-driver": "journald",
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"signature-verification": false
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}
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```
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To:
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```
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{
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"log-driver": "journald",
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"signature-verification": false,
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"experimental": true,
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"registry-mirrors": ["https://<your registry mirror FQDN>"]
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}
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```
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Then restart docker by running:
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````
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systemctl restart docker-latest
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````
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!!! tip ""
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Note the extra comma required after "false" above
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## Chef's notes
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### Tip your waiter (support me) 👏
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Did you receive excellent service? Want to make your waiter happy? (_..and support development of current and future recipes!_) See the [support](/support/) page for (_free or paid)_ ways to say thank you! 👏
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### Your comments? 💬
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