storagesim

A local S3 answering the path-style calls the product makes (PUT, GET, HEAD, DELETE object; HEAD and PUT bucket; ListObjectsV2, so upgradelab snapshots work against it), with SigV4 (header or presigned) checked against one dev key. Code: services/sims/storagesim, console apps/sims/src/storage.

Run it

• On by default in haven (-storage turns it off). Runs in the go lane by default (see sims).
• Console and S3 endpoint: https://storage.<slug>.langwatch.localhost (console at /_sim/); haven status shows the loopback port for drivers.
• Overlay sets STORED_OBJECTS_BACKEND=s3, S3_BUCKET_NAME=langwatch, S3_ENDPOINT, dummy keys (storagesim / storagesim), unless .env names them.
• Standalone: make service svc=storagesim (:5590).

Inspect and assert

GET    /_sim/api/buckets   /objects   /object?bucket=&key=   /object/raw?bucket=&key=
GET    /_sim/api/requests            recent S3 calls: status, auth (presigned|header|none), requestId
GET    /_sim/api/presign?bucket=&key=[&method=PUT][&expires=s]   a presigned URL for this host
GET|PUT /_sim/api/settings   {"forcedError": 0|4xx|5xx}: PUT, GET and HEAD object answer an S3 InternalError with that status
POST   /_sim/api/seed                adds the demo objects, answers {"seeded": n}
DELETE /_sim/api/object?bucket=&key=   one object
DELETE /_sim/api/objects[?bucket=]     every object (in one bucket), answers {"deleted": n}

Private-storage org: bucket langwatch-private always exists; export DATAPLANE_S3__dev__<orgId>= main's JSON (endpoint = the stack's S3 endpoint, that bucket, keys storagesim) before haven up.

Or use any S3 client with path-style addressing, region auto, the dev key. A missing key answers NoSuchKey.

Seed and reset

• STORAGESIM_SEED=1 (haven sets it) stores seed/hello.txt and seed/sample.json in langwatch; existing objects are left alone. The console's "Add demo objects" and haven sim storage seed do the same on demand.
• Objects live in STORAGESIM_DATA_DIR (haven: storage/<slug>/ under its home); haven db reset removes it. haven sim storage clear [bucket] empties it without a reset.

Tests and load

• Hit the loopback port directly; presign with the AWS SDK against that endpoint.
• Object operations take one of 64 striped locks, so distinct keys do not serialise. Benchmark: go test -bench . -benchmem ./services/sims/storagesim.
• Limits: single PUT up to 5 GiB, keys up to 1024 bytes; ListObjectsV2 only (no v1 listing, no ListBuckets), no multipart or versioning. Listing reads every sidecar per page.

From a terminal or agent

--json on every read; non-zero exit on failure; --stack <slug> reads another worktree.

haven sim storage buckets | objects [bucket] | list
haven sim storage object <bucket> <key> [--raw]     # --raw writes the stored bytes to stdout
haven sim storage delete <bucket> <key>
haven sim storage clear [bucket]                    # every bucket without one
haven sim storage presign <bucket> <key> [--put] [--expires=<s>]   # GET by default, 3600 s
haven sim storage fault <4xx|5xx|off>            # PUT/GET object refused with that status; off clears it
haven sim storage seed                              # the demo objects, as STORAGESIM_SEED does