computer-playbook/roles/svc-registry-cache

Docker Registry Cache

Description

Cluster-local Docker Hub pull-through cache. Worker nodes pull base images via this mirror instead of going to registry-1.docker.io for every node, eliminating duplicate network transfers and avoiding Docker Hub rate limits.

Overview

The role deploys a single registry:2 instance in pull-through proxy mode on its inventory group's host. Because the group typically holds exactly one host (the swarm manager), DEPLOYMENT_MODE resolves to compose for the role; multi-host fan-out for the cache itself is out of scope for v1.

Any host that should consume the cache joins the role's group as well. The shared daemon.json template then emits a registry-mirrors block pointing at http://<cache-host>:<cache-port> plus an insecure-registries entry so plain-HTTP communication with the cache is permitted.

Cosmos

The diagram places Docker Registry Cache in the Infinito.Nexus cosmos: the components it deploys (capabilities), the central services it consumes (dependencies), and its outward reach (federation and bridged external networks).

flowchart LR
    subgraph deps [Dependencies]
        dep_svc_bkp_volume_2_local["svc-bkp-volume-2-local 💻"]
        dep_svc_swarm_node["svc-swarm-node 💻"]
    end
    subgraph role [svc-registry-cache 🐳]
        svc_node["node"]
        svc_cache["cache"]
        svc_container_backup["container_backup"]
    end
    dep_svc_bkp_volume_2_local -- "1:1" --> svc_container_backup
    dep_svc_swarm_node -- "1:1" --> svc_node

Solid 1:1 edges are fixed relationships; dashed 0..1 edges are conditional (enabled only in matching deployments); red 0..0 edges are turned off in this role. Node markers show the role's deploy modes (💻 host, 🐳 compose, 🐝 swarm); ❌ marks a service that is explicitly turned off, and ⚙️ an Ansible role dependency declared in meta/main.yml.

Features

• Transparent Docker Hub mirror via registry:2's built-in proxy mode.
• Idempotent: subsequent role runs reuse the populated cache volume.
• Zero per-image configuration: any image normally pulled from Docker Hub is cached on first access and served from local disk afterwards.
• First pull of any image: cache miss, fetched upstream, persisted to disk.
• Subsequent pulls of the same image from any node: served from local cache over LAN. On a 3-node cluster pulling identical base images this is the difference between three full Hub downloads and one Hub download plus two LAN copies.

Quick Setup

Development

Clone, set up the workstation, and deploy Docker Registry Cache onto the local stack:

git clone https://github.com/infinito-nexus/core.git
cd core
make onboard
make compose-deploy mode=reinstall apps=svc-registry-cache full_cycle=false

Production

Run the published image to provision the inventory and deploy Docker Registry Cache to a managed server (the mounted volume persists the inventory):

APP=svc-registry-cache
HOST=<your-server>
DOMAIN=<your-domain>
TLS_MODE=self_signed
SSH_PUBLIC_KEY="<your-ssh-public-key>"

docker run --rm -it \
  -v "$PWD/inventories:/etc/infinito.nexus/inventories" \
  -e APP="$APP" -e HOST="$HOST" -e DOMAIN="$DOMAIN" -e TLS_MODE="$TLS_MODE" -e SSH_PUBLIC_KEY="$SSH_PUBLIC_KEY" \
  ghcr.io/infinito-nexus/core/debian bash -c '
    INVENTORY=/etc/infinito.nexus/inventories/production
    infinito administration inventory provision "$INVENTORY" \
      --inventory-file "$INVENTORY/devices.yml" \
      --host "$HOST" \
      --include "$APP" \
      --vars "{\"TLS_MODE\": \"$TLS_MODE\", \"DOMAIN_PRIMARY\": \"$DOMAIN\", \"users\": {\"administrator\": {\"authorized_keys\": [\"$SSH_PUBLIC_KEY\"]}}}" &&
    infinito administration deploy dedicated "$INVENTORY/devices.yml" \
      --password-file "$INVENTORY/.password" \
      --diff -vv'

Credits

Implemented by Kevin Veen-Birkenbach. Part of the Infinito.Nexus Project and maintained by Kevin Veen-Birkenbach. Licensed under the Infinito.Nexus Community License (Non-Commercial).