Post by stefano — LittleFedi

Stefano Testing Something Cool

@stefano

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The Raspberry PI 0 W, NetBSD, powering this instance

LittleFedi: light, yet complete

I'm writing this post from a Raspberry Pi Zero W - 512 MB RAM, single-core ARMv6 - running NetBSD, powered by littleFedi. The process sits at 33 MB RSS, CPU basically asleep:

load averages: 0.05, 0.08, 0.09<br>CPU states: 0.0% user, 0.0% nice, 0.0% system, 1.0% interrupt, 99.0% idle<br>Memory: 301M Free<br>PID COMMAND RES STATE<br>2082 littlefedi-armv6 33M kqueue

No Redis. No PostgreSQL (but optional). No Sidekiq. No Node.js build pipeline. One statically-linked binary, one SQLite file, and the full fediverse experience. And this is the part people tend to miss: the same binary that runs happily on a Pi Zero scales, on the right hardware, to numbers that have nothing to do with "lightweight". It's not a toy that stays a toy. It's built to grow when you need it to.

What LittleFedi actually ships

Federation - Full ActivityPub S2S: WebFinger, NodeInfo 2.1, host-meta, HTTP Signatures with anti-impersonation checks. Per-user and shared inboxes, outbox, followers, following, featured collections. Thread completion with bounded on-demand fetching of missing ancestors/replies (separate sync and background budgets, all hard-capped). Quote posts via FEP-044f with the full approval handshake (QuoteRequest -> QuoteAuthorization), matching Mastodon 4.4 semantics, plus _misskey_quote and Fedibird quoteUri aliases. Account migration (Move), both outgoing and incoming, with alsoKnownAs linking, automatic follower migration, follow import from AP collections, and CSV export/import. Remote interaction discovery - async like/boost resolution from origin servers with REST fallback.

Mastodon API - Broad coverage: timelines (home, public, local, hashtag, bubble, direct), status CRUD with edits, scheduled posts, polls, bookmarks, lists (with replies_policy and exclusive), filters v2 (keyword CRUD), featured tags, followed hashtags (posts appear in home), markers, conversations, notifications with type exclusion, follow requests, blocks (federated Block/Undo), mutes with duration/expiry and hide_notifications, per-user domain blocks. OAuth2 with app registration, authorization code, client credentials and refresh_token flows, PKCE, consent screen, and scope enforcement (read/write/admin:read/admin:write). It talks fine to Elk, Tusky, Ivory, Phanpy, Semaphore and MastoBlaster.

Streaming - WebSocket and SSE. In-process pub/sub hub with per-connection send buffers, zero cost when no client is connected. Broadcast streams for public, local, remote, hashtags and lists. Per-account streams for user timeline, notifications and direct messages. Optional PostgreSQL LISTEN/NOTIFY backend for cross-process fan-out. Mastodon-compatible event serialization.

Push notifications - Full Web Push / VAPID (RFC 8030/8291) with aes128gcm encryption. Per-type alert toggles (mention, follow, reblog, favourite, poll, follow_request, status). Notify-bell support on followed accounts. Subscription expiry detection, rate-limit handling, 5-retry delivery.

Media pipeline - Upload processing: thumbnail generation (600x600), blurhash computation, EXIF stripping, magic-byte validation, SVG rejection, MIME mismatch detection, UUID-based file renaming. Size limits (40 MB default), pixel caps (16 MP default, tunable down to 4 MP for SBCs).

Media privacy proxy - This is the part I actually care about most. All remote media streams through the instance via HMAC-signed URLs (/proxy/media?url=...&sig=...), so local users never expose their IP address to remote servers. SSRF-guarded: DNS resolution check, private/CGNAT IP rejection, redirect re-validation. Pure io.Copy pass-through, no disk, no decode, ~32 KB buffer. Forwards HTTP Range requests for audio/video seeking. Configure a proxy_secret for stable URLs across restarts. On low-RAM devices, set cache_remote = "off" and you still see every image on the fediverse, the instance just doesn't store or process them.

Remote media caching - Three modes: off, eager (background sweep caches all remote attachments, avatars, headers and emoji, backfills existing on mode switch), lazy (cache on first access). Content-addressed, deduplicated by origin URL. Age-based pruning with file GC. Negative-cache for permanently dead URLs. Transparent origin fallback on cache miss. Open Graph preview cards stored durably with posts.

S3-compatible storage - A separate build tag (-tags s3), deliberately excluded from the default binary to keep it small. Supports AWS S3, MinIO, SeaweedFS, Ceph, Backblaze B2, Wasabi, DigitalOcean Spaces. Native media migration CLI: littlefedi admin media storage-migrate between local and S3 (DB-queue-backed, resumable, bounded batches). storage-status, storage-cancel, storage-resume commands. storage-manifest for rclone JSONL integration.

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