computer-playbook/docs/contributing/environment/cache.md

Local Caches 📦

Three local cache services accelerate re-deploys, reduce upstream traffic, and harden the development workflow against transient upstream outages. They share one compose profile (cache) and one override file (compose/cache.override.yml) and are gated together by profile.py: active on developer machines, inactive on CI runners.

Services 🧩

Registry Cache 🐳

registry-cache runs rpardini/docker-registry-proxy and transparently MITMs every Docker image pull from the inner dockerd, regardless of upstream registry (docker.io, ghcr.io, mcr.microsoft.com, …). The runner trusts the proxy CA via registry-ca.sh.

Pulls only. Pushes are not intercepted.

Package Cache 📚

package-cache runs sonatype/nexus3 and exposes pull-through proxies for package-manager downloads:

Format	Repo names	Upstream
apt	apt-debian, apt-debian-security, apt-ubuntu, apt-ubuntu-security	deb.debian.org; both Ubuntu repos take the first entry of INFINITO_APT_UBUNTU_MIRRORS
apt (mirrors)	apt-debian-mirror, apt-debian-security-mirror, apt-ubuntu-mirror, apt-ubuntu-security-mirror	ftp.debian.org, security.debian.org; both Ubuntu repos take the second entry of INFINITO_APT_UBUNTU_MIRRORS
pypi	pypi-proxy	pypi.org (incl. files.pythonhosted.org)
npm	npm-proxy	registry.npmjs.org
rubygems	gem-proxy	rubygems.org
go	go-proxy	proxy.golang.org
helm	helm-bitnami	charts.bitnami.com/bitnami
yum	yum-rocky, yum-fedora	download.rockylinux.org, download.fedoraproject.org
raw	raw-githubusercontent, raw-codeload-github, raw-packagist, raw-alpine	raw.githubusercontent.com, codeload.github.com, repo.packagist.org, dl-cdn.alpinelinux.org

A proxy repo that holds a cached copy serves it when its remote is unreachable, regardless of metadataMaxAge (measured). autoBlock is therefore off: while a remote is auto-blocked Nexus answers 404 Remote Auto Blocked instead of falling back to that cached copy. The mirror repos below only come into play when nothing is cached either.

Every apt suite exists twice, once per upstream mirror. Nexus has no group repository type for apt (only maven, raw, docker, yum, npm, pypi, rubygems, go and friends), so the failover lives in the frontend: a request that the primary repo answers with 502/503/504 is re-run against the -mirror repo, which proxies a different host. 404 deliberately does not retry, because a missing file is missing on both mirrors and apt probes for missing files often. The frontend waits at most 8 s for a primary before it re-runs the request against the mirror; the -mirror locations keep the global 300 s.

Bootstrap is idempotent and runs from bootstrap.sh once the stack is healthy. It loops over INFINITO_CACHE_UPSTREAMS and holds no repository of its own.

Package Cache Frontend 🔐

package-cache-frontend runs nginx:alpine and reverse-proxies upstream package-manager hostnames onto the matching Nexus repo path. Combined with extra_hosts DNS-hijack on consumers, package managers can hit their real upstream URL and still flow through the cache.

Two listener layers:

• HTTPS (port 443): per-hostname server certs signed by a dedicated CA. Used by the infinito runner (Ansible-driven pip install, gem install, composer install, curl https://…). The runner trusts the CA via ca.sh.
• HTTP (port 80): plain mirrors for deb.debian.org, archive.ubuntu.com, security.ubuntu.com, dl-cdn.alpinelinux.org. Used by inner-dockerd Dockerfile builds via build.extra_hosts DNS-hijack. No CA-trust required in the build container.

Cert generation runs in a throw-away alpine container driven by certs.sh before the frontend starts. It issues a leaf for each name in INFINITO_CACHE_TLS_HOSTS and holds no hostname of its own.

Activation 🎚️

The cache decision is exposed via Profile.cache_stack_enabled() in profile.py. When active:

• compose/cache.override.yml is layered on top of the base compose.yml by compose.py and down.py via common.pycompose_file_args.
• The cache services are added.
• The runner's infinito service receives:
  • bind-mounts for the registry-cache CA, the package-cache client snippets (pip.conf, npmrc, apt/${INFINITO_DISTRO}.list), and the frontend CA file
  • extra_hosts entries DNS-hijacking the HTTPS upstream hostnames to the frontend's static IP
  • INFINITO_CACHE_PACKAGE_FRONTEND_IP env var for the inner compose wrapper
• Cert generation, Nexus repo bootstrap, and runner trust-store install run from compose.py.

When inactive, the override is omitted: cache services do not exist, the runner has no cache mounts or DNS-hijack, package managers go direct to upstream.

CI signals (GITHUB_ACTIONS=true, INFINITO_RUNNING_ON_GITHUB=true, CI=true) deactivate. Fresh runner disks per CI job give no cross-run amortization.

Coverage Matrix 📋

Traffic	Mechanism	Cached
Image pulls (any registry, inner dockerd)	registry-cache MITM via HTTP_PROXY env on dockerd	✓
apt-get install (Ansible task in runner)	apt/${INFINITO_DISTRO}.list URL-rewrite to package-cache:8081	✓
pip install (Ansible task in runner)	pip.conf URL-rewrite	✓
npm install (Ansible task in runner)	.npmrc URL-rewrite	✓
gem, composer, go, curl https://… (Ansible task in runner)	DNS-hijack + frontend HTTPS + runner CA-trust	✓
RUN apt-get install (inner Dockerfile build, Debian/Ubuntu)	build.extra_hosts DNS-hijack + frontend HTTP	✓
RUN apk add (inner Dockerfile build, Alpine ≤3.17 HTTP)	build.extra_hosts DNS-hijack + frontend HTTP	✓
RUN pip/npm/gem/composer/go install (inner Dockerfile build)	none today	✗
RUN apk add (Alpine ≥3.18 HTTPS)	none today	✗
App container runtime traffic (HTTPS to external API)	none today	✗

The HTTPS-only inner-build gap requires per-image CA-trust bootstrap, which is out of scope for the current minimal-invasive design.

Compose Wrapper Auto-Detection 🪄

The runner's compose wrapper at roles/sys-svc-compose/files/python/compose.py auto-detects compose files when invoked from per-app directories under /opt/compose/<app>/:

File	When
compose.yml	always
compose.override.yml	when present (role provides it)
compose.ca.override.yml	when present (TLS self-signed CA-inject runs)
compose.cache.override.yml	generated on the fly when INFINITO_CACHE_PACKAGE_FRONTEND_IP is set; emits build.extra_hosts for every service that has a build: key

pull.py delegates to the same wrapper so pull and build --pull operations see the identical -f set.

Environment Variables 🌳

The host-side env-vars (INFINITO_CACHE_REGISTRY_*, INFINITO_CACHE_PACKAGE_*) are declared in default.env and the dynamic ones (cache sizes from df//proc/meminfo, sha256 admin password) are computed by utils/env/builder.py. make dotenv writes them into .env, which Compose auto-loads and which BASH_ENV makes available to every Makefile recipe through scripts/meta/env/load.sh. See variables.md.

Per-variable defaults and purposes are in compose.yml.md under the cache section.

INFINITO_CACHE_PACKAGE_MAX_AGE_MIN (default 8640 = 6 days) controls how long every Nexus proxy repo holds an upstream response before revalidating. The bootstrap helper applies it as contentMaxAge, metadataMaxAge, and negativeCache.timeToLive. The default is intentionally one day below the 7-day Valid-Until window Debian and Ubuntu generate in their apt Release files, so Nexus always refreshes the manifest before apt-get update would see it expired. Raise it for slow-moving upstreams when staleness is preferable to upstream load; lower it further for fast-moving feeds (apt-debian-security, branch-pinned tarballs) when staleness becomes visible.

Operations 🛠️

Action	Command
Start the stack with caches	make compose-up
Stop the stack	make compose-down
Install this checkout's cache: declarations into the running stack	make cache-apply
Wipe local cache state	make clean-cache
Manually re-bootstrap Nexus repos	bash roles/svc-cache-package/files/shell/bootstrap.sh (after make dotenv or sourcing scripts/meta/env/load.sh)
Manually regenerate frontend certs	bash roles/svc-cache-package/files/shell/certs.sh
Regenerate every derived cache file	make dotenv
Reload nginx in the frontend	docker exec infinito-package-cache-frontend nginx -s reload
Inspect cache hits	docker logs -f infinito-package-cache and docker logs -f infinito-package-cache-frontend

Cache state persists under /var/cache/infinito/core/cache/. Paths are configurable via the env scripts above.

Adding a New Upstream ➕

When a new package manager or upstream needs caching:

Declare it under cache: in a meta/networks.yml, then run make dotenv followed by make cache-apply. That file is the single point of truth; the Nexus repo, the leaf cert, the nginx server block, the extra_hosts entries, pip.conf, .npmrc and the apt sources are all derived from it. make dotenv renders them, make cache-apply installs them into the running stack: it creates the Nexus proxy repositories, issues the frontend's leaf certificates, copies the upstream map onto the path the frontend mounts and reloads it. Recreate the checkout's runner with make compose-up afterwards so the new DNS hijacks reach it.

Every checkout renders and applies its own map, so a branch that declares a new host serves it without waiting for a merge. The frontend mounts one map and make cache-apply replaces it, so whichever checkout applied last is the one it serves. Two checkouts sharing a stack therefore overwrite each other: run make cache-apply from the one whose declarations you need.

A TLS upstream only reaches an inner image build when that build trusts the frontend's CA: the compose wrapper hands a build the plain-HTTP hosts by default and the full host list only when its Dockerfile runs package-frontend-ca.sh (see svc-ai-ltengine for the three lines and the two staging tasks that go with them).

Put the declaration in the role that needs the upstream. An upstream no single role owns goes in svc-cache-package.

cache:
  repos:
    raw-example:
      flavor: raw
      upstream: https://example.org/
  hosts:
    example.org:
      repo: raw-example

A repository is proxied by Nexus. A host is additionally answered for by the frontend, so a client keeps addressing its real upstream URL. listen: [80] serves it over plain HTTP and issues no certificate; paths: maps several repositories under one host; mirror: on a repository names the sibling the frontend retries against on 502, 503 or 504; passthrough: true suits an upstream that hands out URLs already carrying the repository prefix.

A deployed host may correct or extend any of this from its inventory under applications.svc-cache-package.repos and .upstreams; the dev stack has no inventory and uses the declarations unchanged.

Background 📚

• Compose-file env-var contract: compose.yml.md
• Profile gating mechanics: profile.py