When a mutable file's TTL expires and the upstream backend cannot be
contacted (network error or timeout), the cached copy is kept and its
TTL refreshed instead of being evicted. This keeps RPM repodata, Alpine
indexes, branch archives, and other mutable data available during
upstream outages.
Adds UpstreamUnreachable exception and _upstream_reachable() helper.
check_upstream_changed() now raises UpstreamUnreachable on network
errors (was silently returning True). handle_expired_mutable() catches
the exception on the check_mutable_updates path and calls
_upstream_reachable() on the plain-expiry path.
README updated to current immutable/mutable terminology and documents
all new caching features.
Deduplicates the expired-mutable TTL/redownload branching logic that
was copied verbatim between get_artifact and docker_v2_proxy. Adds the
missing happy-path test for a changed mutable file that is successfully
re-fetched from upstream.
When check_mutable_updates: true is set on a remote, expired user-defined
mutable files are revalidated before re-downloading:
- On expiry a conditional HEAD is sent with If-None-Match / If-Modified-Since
- 304 Not Modified: TTL is refreshed in Redis, S3 cache is untouched
- 200 / no conditional support: cache is invalidated and file re-downloaded
- Network error: safe fallback — assume changed, re-download
ETag and Last-Modified from upstream responses are stored in Redis under
mutable:meta:<remote>:<hash> (no expiry, cleaned up on re-download or
cache flush). The flag only applies to user-configured mutable_patterns;
built-in package-type defaults (APKINDEX, repomd.xml, Docker manifests)
are always re-fetched unconditionally.
cache/flush also clears mutable:meta:* keys alongside index:* keys.
Remove remotes.yaml from .gitignore and add header comments explaining
the immutable_patterns/mutable_patterns/cache keys. Marks the file
clearly as an example to copy and adapt; warns against committing
real credentials.
Replace the include_patterns/index_patterns split with a clearer
immutable_patterns/mutable_patterns model:
- immutable_patterns: artifacts cached indefinitely (no TTL)
- mutable_patterns: artifacts that expire and are re-fetched after
cache.mutable_ttl seconds (replaces cache.index_ttl)
_PACKAGE_INDEX_PATTERNS renamed to _PACKAGE_MUTABLE_PATTERNS; all
built-in package-type index patterns (APKINDEX, repomd, manifests, etc.)
default to the remote's mutable_ttl (default 1 hour).
cache.file_ttl renamed to cache.immutable_ttl for consistency.
Adds github-archive remote to remotes.yaml as a worked example showing
tag archives as immutable and branch archives as mutable (1-day TTL).
docker-compose.yml: fix VERSION=dev → 2.2.2.dev0 (valid PEP 440),
add :z SELinux label to volume mounts.
unkinben