mule-image/sidecar

mule-sidecar

Go + Gin + GORM service for the endpoints PhotoPrism's REST API does not expose. Same wire contract as the M3 Node prototype it replaces; the SvelteKit client at web/ talks to it transparently through Vite's /api/sidecar/* proxy.

What it owns

Method	Path	Purpose
GET	/api/sidecar/healthz	Unauthenticated liveness probe.
GET	/api/sidecar/photos/marks	Every per-photo {rating, color} mark.
GET	/api/sidecar/photos/:uid/marks	One photo's mark (or {} if none).
PUT	/api/sidecar/photos/:uid/marks	Patch one photo's mark.
POST	/api/sidecar/photos/marks/bulk	Stamp the same mark onto many photos.
POST	/api/sidecar/files/:uid/rename	Rename the primary file on disk + reindex.
POST	/api/sidecar/folders	Create a folder under ${ORIGINALS_ROOT}.
POST	/api/sidecar/folders/:rel/rename	Rename a folder (rel path URL-encoded).
DELETE	/api/sidecar/folders/:rel	Delete an empty folder.
POST	/api/sidecar/albums/:uid/convert	Move/copy every photo in a heap into folder X.
GET	/api/sidecar/duplicates/scan	Walk originals, return same-hash groups.
POST	/api/sidecar/duplicates/archive	Move duplicate paths into .duplicates/<ts>/.

Auth: every endpoint except healthz requires the caller's X-Auth-Token header. The sidecar holds no service credentials — it proxies the token straight back to PhotoPrism's /api/v1/photos?count=1 to confirm the session is live before doing anything destructive.

Marks persist to MariaDB (mule_sidecar.marks); everything else operates on the filesystem under ${ORIGINALS_ROOT} and triggers a PhotoPrism reindex of the affected parent in the background.

Run

The sidecar is a sidecar service in the PhotoPrism compose stack. Bringing the whole stack up brings it up too:

podman-compose --env-file .env \
  -f docker-compose.yml \
  -f docker-compose.podman.yml \
  up -d

This builds Dockerfile (multi-stage golang:1.25-alpine → gcr.io/distroless/static, ~12 MB final image), starts the container, and binds 127.0.0.1:8000 to the service. The SvelteKit dev server proxies /api/sidecar/* to that port transparently.

Dev-iteration loop (host build)

For tight iteration without rebuilding the image on every change you can run it as a host process — Go is already on the dev machine:

cd sidecar
go build -o mule-sidecar .

ORIGINALS_ROOT=/path/to/photoprism/originals \
PHOTOPRISM_BASE_URL=http://localhost:2342 \
SIDECAR_PORT=8000 \
./mule-sidecar

The host build connects to mariadb via the loopback port the compose file publishes; stop pp-sidecar first so they don't fight for 8000.

Env

Var	Default	Notes
ORIGINALS_ROOT	/photoprism/originals	Absolute path; must match PhotoPrism's mount.
PHOTOPRISM_BASE_URL	http://localhost:2342	Where to reach PhotoPrism for session validation + reindex calls.
SIDECAR_PORT	8000	Loopback-only; reverse-proxy fronts it in production.
SIDECAR_DSN	(built from the vars below)	Set this to override the assembled MySQL DSN entirely.
SIDECAR_DB_HOST	127.0.0.1	Host of the MariaDB the compose stack publishes on 127.0.0.1:3306.
SIDECAR_DB_PORT	3306
SIDECAR_DB_USER	sidecar	Provisioned by mariadb/init/01-sidecar.sql on first boot.
SIDECAR_DB_PASSWORD	replace-at-m4-bringup	Literal placeholder — rotate before any non-local deployment.
SIDECAR_DB_NAME	mule_sidecar

Schema

GORM AutoMigrate creates the only table the service owns:

CREATE TABLE marks (
  photo_uid  VARCHAR(64) PRIMARY KEY,
  rating     BIGINT NULL,
  color      VARCHAR(16) NULL,
  updated_at DATETIME(3)
);

The M3 Node prototype kept the same data in sidecar/data/marks.json. There is no migration path — the prototype's marks file was dev-only state. Heap-sharing tables (M4) will land in subsequent migrations.

Layout

sidecar/
├── Dockerfile            multi-stage golang:1.25 → distroless/static
├── main.go               entrypoint, route wiring, graceful shutdown
├── config.go             env-driven Config
├── db.go                 GORM open + Mark model + AutoMigrate
├── auth.go               requireSession middleware + ctxToken
├── fs.go                 path safety, walk, sha1
├── pp.go                 PhotoPrism HTTP client (validateSession, reindex)
├── handlers_rename.go
├── handlers_folders.go
├── handlers_marks.go
├── handlers_heap.go
└── handlers_dups.go