feat: optional S3-compatible storage for uploaded images, instead of the local upload directory

docs/docker.md

@@ -102,6 +102,19 @@ To use MariaDB, change the `mysql` service image to `mariadb:11`, its `MYSQL_*`
 
 Back the database up with `docker compose -f docker-compose.mysql.yml exec mysql mysqldump ...` (a `tar` copy of the volume is not consistent while it runs), and the `renewcms-data` volume as described above. Moving an existing SQLite volume is a manual procedure, see [deployment.md](deployment.md#moving-an-existing-sqlite-site-to-mysql).
 
+## S3-compatible storage (SeaweedFS)
+
+[`docker-compose.s3.yml`](../docker-compose.s3.yml) runs RenewCMS with `STORAGE_DRIVER=s3` next to a [SeaweedFS](https://github.com/seaweedfs/seaweedfs) server (Apache 2.0, image `chrislusf/seaweedfs`, override with `SEAWEEDFS_IMAGE`) with its S3 gateway enabled, and a one-shot `seaweedfs-init` step that creates the bucket with `weed shell`:
+
+```sh
+export S3_SECRET_ACCESS_KEY=<generated>
+docker compose -f docker-compose.s3.yml up -d
+```
+
+RenewCMS gets `S3_ENDPOINT=http://seaweedfs:8333`, `S3_PATH_STYLE=true`, the bucket name and the access key (`S3_ACCESS_KEY_ID`, default `renewcms`, and `S3_SECRET_ACCESS_KEY`) from the compose file, and the rest from `docker.env`. SeaweedFS reads the same key pair as its admin identity. The `renewcms-data` volume then holds the SQLite database and update state but no uploads; the images live in the `seaweedfs-data` volume. The bucket is not published and the app serves the images. SeaweedFS is used because MinIO stopped publishing community images. To use AWS S3 or another provider, drop the `seaweedfs` services and set the `S3_*` variables in `docker.env` (see [configuration.md](configuration.md#image-storage)). The volume backup above covers the database only, so back the bucket up separately. To move existing uploads see [configuration.md](configuration.md#moving-existing-uploads-to-a-bucket).
+
+`task test:s3` starts a throwaway SeaweedFS and runs the storage integration test against it; it skips with a message when Docker is not available.
+
 ## Reverse proxy and TLS
 
 With `ENVIRONMENT=production` the site must be served over HTTPS, so put a reverse proxy in front and set `PUBLIC_URL` to the public `https://` address. Bind the published port to the host only when the proxy runs on the same host, by changing `ports` to `"127.0.0.1:8080:8080"`.