Add a per-remote mirror_strategy selector for the mirrorlist, supporting
round_robin (default, unchanged) and least_conn.
- models.Remote gains MirrorStrategy string + MirrorStrategy{RoundRobin,LeastConn}
constants and ValidateMirrorStrategy (enum check; least_conn requires a
non-empty mirrorlist). Empty behaves as round_robin for back-compat.
- DB: additive mirror_strategy TEXT NOT NULL DEFAULT 'round_robin' column
(CREATE TABLE + ADD COLUMN IF NOT EXISTS), wired through remoteCols/scanRemote/
CreateRemote/UpdateRemote; empty normalized to round_robin on write.
- Engine: least_conn starts each attempt with the pool URL holding the fewest
in-flight requests via a per-remote/per-URL atomic gauge (incremented around
each upstream call in head/fetch/checkUpstream), ties broken by the existing
round-robin rotation. Round-robin path and failover order unchanged;
single-URL pools are a no-op.
- Tests: unit tests for least-loaded selection, round-robin default, gauge
inc/dec, single-URL no-op, and strategy validation; DB round-trip covers the
new column; docker e2e adds a least_conn distribution test and a real dnf
install through a least_conn remote.
## Why
OS package remotes (rpm/deb/apk) fetch many small files and benefit from spreading upstream load across mirrors and surviving a mirror outage. A remote may now set a **`mirrorlist`** of additional upstream base URLs. The effective upstream pool is **`[base_url] + mirrorlist`**, which the shared proxy engine load-balances **round-robin** and, on a network error/timeout/5xx, **fails over** to the next mirror before returning an error. Selection happens in the engine, so it works for every provider that reaches upstream.
**Backward compatible:** `base_url` stays a plain string (providers read it unchanged), and a remote with **no mirrorlist behaves exactly as today** (single attempt, same error path).
## How
- `models.Remote.Mirrorlist` (`[]string`, `json:"mirrorlist,omitempty"`) + `UpstreamPool()` = `[base_url] + mirrorlist`.
- `ValidateMirrorlist`: a non-empty mirrorlist is allowed **only** when `repo_type==remote` **and** `package_type ∈ {rpm, deb, alpine}`; each entry must be an http/https URL. Enforced in the v2 create/update handlers (400 otherwise); `base_url` stays required for remotes.
- Persist the mirrorlist in a new additive `mirrorlist TEXT[]` column (`remoteCols`/`scanRemote`/`CreateRemote`/`UpdateRemote`); the `base_url` column is unchanged.
- Engine keeps a per-remote round-robin cursor over the pool; the fetch/head/revalidate upstream calls run in a failover loop that narrows the remote to one selected mirror per attempt. Only network errors and 5xx fail over (404/403/… return as-is). The circuit breaker stays keyed per remote and trips only after all mirrors fail.
## Scope
Round-robin + failover only, restricted to **remote rpm/deb/apk** repos. Least-connections and a per-remote strategy selector are a **follow-up PR**.
## Tests
- Unit: model JSON round-trip + validation gating (rejected on non-rpm/deb/apk and on local, accepted on rpm/deb/apk, bad URL rejected), engine round-robin/failover/no-mirrorlist-unchanged, DB mirrorlist round-trip. `make test` (`go test -race`) green.
- Docker acceptance (`e2e-docker`, `dockere2e` tag, wired into `docker-e2e.sh`): round-robin distribution across two mock upstreams, failover past a dead primary, no-mirrorlist regression, and a **real `dnf` makecache + install** through a two-mirror rpm remote whose `base_url` is dead. All four pass locally.
Reviewed-on: #121
Co-authored-by: unkin-agent <unkin-agent@unkin.net>
Co-committed-by: unkin-agent <unkin-agent@unkin.net>
Fixes#72
## Why
`compilePatterns` silently discards any pattern that fails to compile. A typo in a blocklist entry therefore turns a deny rule into a no-op — a fail-open with security impact.
## Changes
- Add `Remote.ValidatePatterns`, which compiles every pattern list (patterns, blocklist, mutable/immutable patterns, ban_tags) and returns an error on the first invalid regex.
- Reject invalid patterns with 400 at remote create and update time.
- Unit test for valid and invalid patterns.
## Validation
- `go test ./pkg/models/` and `make e2e` pass.
Reviewed-on: #87
Co-authored-by: Ben Vincent <ben@unkin.net>
Co-committed-by: Ben Vincent <ben@unkin.net>
unkin-agent
unkinben