## running different pieces of atproto

for how the pieces fit together:
[atproto for distsys engineers](https://atproto.com/articles/atproto-for-distsys-engineers).
it frames the firehose as an event log and appviews as precomputed views over it

nothing below needs a specific vendor. i often use [fly](https://fly.io) for small services out
of habit — [render](https://render.com), [railway](https://railway.app), or a plain vps on
[hetzner](https://www.hetzner.com/cloud), [digitalocean](https://www.digitalocean.com), or
[ovh](https://www.ovhcloud.com) all work, and a vps is usually cheaper if you know what you're doing

<details>
<summary>glossary</summary>

**client-side apps.** the app is a static bundle. the user signs in with atproto oauth and
reads and writes their own PDS. there is no backend to run.
[doodl](https://doodl.waow.tech) stores drawings as PDS blobs. these do not appear in my
infra costs. i might use a [cloudflare worker](https://developers.cloudflare.com/workers/)
for link previews tho. [wisp.place](https://wisp.place) hosts the bundle on atproto itself,
which is how [at-me](https://at-me.wisp.place) and
[punch](https://sites.wisp.place/zzstoatzz.io/punch/) are served.

**microcosm.** already indexes the whole network, so a lot of what you'd build a backend
for is a http call away. free, no auth, CORS, so the browser can call it directly:

```bash
# how many likes does this post have?
curl "https://constellation.microcosm.blue/xrpc/blue.microcosm.links.getBacklinksCount\
?subject=at://did:plc:xbtmt2zjwlrfegqvch7fboei/app.bsky.feed.post/3mn4baqvpoc26\
&source=app.bsky.feed.like:subject.uri"
# {"total":96}

# who is this, and where is their PDS?
curl "https://slingshot.microcosm.blue/xrpc/com.bad-example.identity.resolveMiniDoc\
?identifier=zzstoatzz.io"
# {"did":"did:plc:xbtmt2zjwlrfegqvch7fboei","handle":"zzstoatzz.io",
#  "pds":"https://pds.zzstoatzz.io","signing_key":"zQ3shpq..."}
```

`source` is just `{collection}:{path}`, so that works for any lexicon, not only bluesky.
[constellation](https://constellation.microcosm.blue) does backlinks (likes, follows,
replies, quotes), [slingshot](https://slingshot.microcosm.blue) does identity and records,
[spacedust](https://spacedust.microcosm.blue) streams live interactions, and
[ufos](https://ufos-api.microcosm.blue) shows what lexicons exist. i wrote
[protopack](https://tangled.org/zzstoatzz.io/protopack) to make agents fluent in them.

**appviews.** an appview consumes the firehose, indexes records, and serves them over xrpc.
[happyview](https://happyview.dev) writes that plumbing for you, so you define lexicons
instead of maintaining a firehose consumer.

for storage, start with sqlite on the machine — one file, fast, usually enough. sqlite is
not highly available, so if you need more than one instance or you can't lose the disk, use
postgres, managed if you'd rather not run it (eg [neon](https://neon.com), which
[plyr.fm](https://plyr.fm) uses). [turso](https://turso.tech) is hosted sqlite with replicas
if you want to stay in that world.

appview cost scales with the size of the corpus, not with traffic. that surprised me.

**PDS.** stock image and a persistent volume. my whole deploy config is
[three files](https://tangled.org/zzstoatzz.io/pds-infra). blobs live on the volume, so
disk is what grows.

**relays.** a relay subscribes to every PDS in the network, so the traffic allowance
decides the machine. check it before you pick a region — hetzner's EU datacenters include
20 TB/mo where their US ones include 3–5 TB.

</details>

### summary of what, how, where and $

figures are what i pay, from a daily snapshot i publish to my PDS as
[`io.zzstoatzz.cost.snapshot`](https://pds.ls/at://did:plc:xbtmt2zjwlrfegqvch7fboei/io.zzstoatzz.cost.snapshot).

| thing | what i run | where | $/mo |
|---|---|---|---|
| client-side app | [doodl](https://doodl.waow.tech), [at-me](https://at-me.wisp.place), [punch](https://sites.wisp.place/zzstoatzz.io/punch/) | any static host — [wisp.place](https://wisp.place) or [cloudflare](https://developers.cloudflare.com/workers/) | ~0 |
| appview (framework) | [status.zzstoatzz.io](https://status.zzstoatzz.io) | [happyview](https://happyview.dev) on one small vm | ~6 |
| appview (custom) | [typeahead](https://tangled.org/zzstoatzz.io/typeahead), [pub-search](https://tangled.org/zzstoatzz.io/pub-search), [coral](https://tangled.org/zzstoatzz.io/coral) | small vm + sqlite, or managed postgres ([neon](https://neon.com)) if you need HA | 5–25 each |
| PDS | [pds.zzstoatzz.io](https://pds.zzstoatzz.io) — stock [bluesky-social/pds](https://github.com/bluesky-social/pds) image | any vm with a persistent volume ([my config](https://tangled.org/zzstoatzz.io/pds-infra)) or [cirrus](https://github.com/ascorbic/cirrus) | 10.64 |
| relay | [relay.waow.tech](https://relay.waow.tech) ([go/indigo](https://github.com/bluesky-social/indigo/tree/main/cmd/relay)) and [zlay.waow.tech](https://zlay.waow.tech) ([zig](https://tangled.org/zat.dev/zlay)) | [hetzner](https://www.hetzner.com/cloud) cx53 and cx43 in `fsn1`, k3s, [terraform](https://tangled.org/zzstoatzz.io/relay) | 34.99 and 18.49 |

before you deploy an appview, check whether [microcosm](https://microcosm.blue) already
answers your question — you deploy nothing and it costs nothing. also i will say that free tier cloudflare is quite generous, pages/workers can take you [a long way](https://bsky.app/profile/zzstoatzz.io/post/3mqsmy6duv225)
and go sponsor fig! https://github.com/sponsors/uniphil