Ceph

Ceph Rados Gateway (RGW) speaks the S3 API with AWS Signature V4 against your own gateway endpoint (e.g. https://ceph.example.com). RGW is self-hosted, so the endpoint is required and path-style addressing is used by default. Credentials (RGW user access key + secret key) are created the same way in both runtimes, see Ceph Credentials.

Node (server-side)

pnpm add @struktoai/mirage-node

import { CephVFS, MountMode, Workspace } from '@struktoai/mirage-node'

const ceph = new CephVFS({
  bucket: process.env.CEPH_BUCKET!,
  endpoint: process.env.CEPH_ENDPOINT_URL!,
  accessKeyId: process.env.CEPH_ACCESS_KEY_ID!,
  secretAccessKey: process.env.CEPH_SECRET_ACCESS_KEY!,
})

const ws = new Workspace({ '/bucket/': ceph }, { mode: MountMode.READ })
const res = await ws.shell('ls /bucket/')
console.log(res.stdoutText)

Config

Field	Description
`bucket` required	Name of the bucket to mount.
`accessKeyId` secret	Access key ID; set it with `secretAccessKey`. Unset uses the AWS SDK credential chain.
`secretAccessKey` secret	Secret access key paired with `accessKeyId`.
`sessionToken` secret	Session token for temporary credentials, sent with the access key pair.
`profile`	Named profile in the shared AWS config and credentials files that supplies credentials when no access key pair is given.
`forcePathStyle` default `true`	Address the bucket in the URL path (`<endpoint>/<bucket>/<key>`) instead of as a subdomain of the endpoint.
`keyPrefix`	Key prefix inside the bucket that the mount treats as its root; keys outside it are not visible. Leading slashes are dropped and a trailing `/` is added.
`timeout` default `DEFAULT_TIMEOUT`	Seconds a request may wait to connect, or between two reads of its answer, before it fails; a download that keeps flowing is never cut off.
`proxy` secret	Proxy URL for every HTTP and HTTPS request to the endpoint.
`region` default `'us-east-1'`	Region requests are signed for; the gateway’s endpoint does not depend on it.
`endpoint` required	URL of the self-hosted S3 gateway, such as `http://localhost:9000`.

Fields marked secret are redacted in snapshots.

Browser (presigned URLs)

pnpm add @struktoai/mirage-browser

The browser CephVFS is secret-free, your backend signs each operation using your RGW keys and returns a URL. RGW accepts AWS Signature V4, so @aws-sdk/s3-request-presigner works, pointed at your gateway endpoint.

Config

Field	Description
`bucket` required	Name of the bucket to mount.
`presignedUrlProvider` required, secret	Function `(path, operation, options)` that returns a signed URL for each S3 operation; your server signs it, so the browser holds no keys.
`region`	Region of the bucket. Most providers derive the endpoint from it; requests go to the host each presigned URL names.
`endpoint`	Endpoint URL that replaces the one the provider derives. Requests go to the host each presigned URL names; the mount uses it to name its storage location.
`defaultContentType` default `'application/octet-stream'`	`Content-Type` stored with every object the mount writes.
`keyPrefix`	Key prefix the mount treats as its root. The browser can change it before a URL is signed, so enforce the prefix on the signing server.
`timeout` default `DEFAULT_TIMEOUT`	Seconds a request may wait to connect, or between two reads of its answer, before it fails; a download that keeps flowing is never cut off.

Fields marked secret are redacted in snapshots.

1. Server: sign URLs with the RGW endpoint

import {
  CopyObjectCommand,
  DeleteObjectCommand,
  GetObjectCommand,
  HeadObjectCommand,
  ListObjectsV2Command,
  PutObjectCommand,
  S3Client,
} from '@aws-sdk/client-s3'
import { getSignedUrl } from '@aws-sdk/s3-request-presigner'

const client = new S3Client({
  region: 'us-east-1',
  endpoint: process.env.CEPH_ENDPOINT_URL,
  forcePathStyle: true,
  credentials: {
    accessKeyId: process.env.CEPH_ACCESS_KEY_ID!,
    secretAccessKey: process.env.CEPH_SECRET_ACCESS_KEY!,
  },
})
const BUCKET = process.env.CEPH_BUCKET!

app.post('/presign/ceph', async (req, res) => {
  const { path, op, opts } = req.body
  const key = path.replace(/^\/+/, '')
  const ttl = typeof opts?.ttlSec === 'number' ? opts.ttlSec : 300
  let cmd
  switch (op) {
    case 'GET':    cmd = new GetObjectCommand({ Bucket: BUCKET, Key: key }); break
    case 'PUT':    cmd = new PutObjectCommand({ Bucket: BUCKET, Key: key, ContentType: opts?.contentType }); break
    case 'HEAD':   cmd = new HeadObjectCommand({ Bucket: BUCKET, Key: key }); break
    case 'DELETE': cmd = new DeleteObjectCommand({ Bucket: BUCKET, Key: key }); break
    case 'LIST':   cmd = new ListObjectsV2Command({
      Bucket: BUCKET,
      Prefix: opts?.listPrefix,
      Delimiter: opts?.listDelimiter,
      ContinuationToken: opts?.listContinuationToken,
    }); break
    case 'COPY':   cmd = new CopyObjectCommand({
      Bucket: BUCKET,
      Key: key,
      CopySource: `${BUCKET}/${opts?.copySource}`,
    }); break
  }
  res.json({ url: await getSignedUrl(client, cmd, { expiresIn: ttl }) })
})

RGW uses path-style URLs (forcePathStyle: true), virtual-hosted style requires wildcard DNS on the gateway.

2. Browser: wire it up

import { CephVFS, MountMode, Workspace } from '@struktoai/mirage-browser'

const ceph = new CephVFS({
  bucket: 'my-bucket',
  endpoint: 'https://ceph.example.com',
  presignedUrlProvider: async (path, op, opts) => {
    const r = await fetch('/presign/ceph', {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({ path, op, opts }),
    })
    const { url } = await r.json()
    return url
  },
})

const ws = new Workspace({ '/bucket/': ceph }, { mode: MountMode.READ })

endpoint on the browser config is only used for display/logging; the actual endpoint is baked into the presigned URLs your backend returns.

3. CORS

RGW supports the S3 PutBucketCors call, so the AWS CLI works against your gateway:

aws s3api put-bucket-cors --bucket "$CEPH_BUCKET" \
  --endpoint-url "$CEPH_ENDPOINT_URL" \
  --cors-configuration '{"CORSRules":[{"AllowedOrigins":["http://localhost:5173","https://app.example.com"],"AllowedMethods":["GET","PUT","HEAD","DELETE","POST"],"AllowedHeaders":["*"],"ExposeHeaders":["ETag","Content-Length","Content-Type","Last-Modified"]}]}'

See the Ceph VFS docs for the equivalent Python wiring. For write: conditional on this provider, see S3-compatible stores.

VFS.md

The VFS.md an agent reads with Ceph mounted at /<path>.

Rendered
Raw

Virtual Filesystem

Path	Description
`/<path>`	`ceph`, write

Supported Unix Commands for VFS

Unix commands work on each path as on a local filesystem, as far as the path supports them:

Path	Supported
`/<path>`	Almost all Unix commands.

Limitations of Unix Commands for VFS

Where a path differs from a local filesystem:

Path	Limitations
`/<path>`	`grep -r`, `find` and `du` stop after 1000 files; a glob matching more, `tar -c`, `cp -r` and `rm -r` are refused.

Run man <cmd> or <cmd> --help for one command’s usage.

---
name: workspace-filesystem
description: The virtual filesystem layout of this workspace.
---

# Virtual Filesystem

| Path | Description |
| --- | --- |
| `/<path>` | `ceph`, write |

## Supported Unix Commands for VFS

Unix commands work on each path as on a local filesystem, as far as the path supports them:

| Path | Supported |
| --- | --- |
| `/<path>` | Almost all Unix commands. |

## Limitations of Unix Commands for VFS

Where a path differs from a local filesystem:

| Path | Limitations |
| --- | --- |
| `/<path>` | `grep -r`, `find` and `du` stop after 1000 files; a glob matching more, `tar -c`, `cp -r` and `rm -r` are refused. |

Run `man <cmd>` or `<cmd> --help` for one command's usage.

Integration

What Ceph answers through its own API, so fewer files are read. Integration explains each command.

Command	On Ceph
`md5sum`	The object’s ETag, when it is the MD5: a single-part upload, unencrypted or under SSE-S3
`find`, `du`, `ls -R`, `tree`	One recursive listing

Getting Started

Access

AI Agents

VFS

CLIs

Runtimes

Node (server-side)

Config

Browser (presigned URLs)

Config

1. Server: sign URLs with the RGW endpoint

2. Browser: wire it up

3. CORS

VFS.md

Virtual Filesystem

Supported Unix Commands for VFS

Limitations of Unix Commands for VFS

Integration

​Node (server-side)

​Config

​Browser (presigned URLs)

​Config

​1. Server: sign URLs with the RGW endpoint

​2. Browser: wire it up

​3. CORS

​VFS.md

​Virtual Filesystem

​Supported Unix Commands for VFS

​Limitations of Unix Commands for VFS

​Integration

Node (server-side)

Config

Browser (presigned URLs)

Config

1. Server: sign URLs with the RGW endpoint

2. Browser: wire it up

3. CORS

VFS.md

Virtual Filesystem

Supported Unix Commands for VFS

Limitations of Unix Commands for VFS

Integration