asyagent 0.2.0

An HTTP service that compiles Asymptote (*.asy) sources into rendered output (PDF, SVG, EPS, PNG, JPG).

asyagent

An HTTP service that compiles Asymptote (*.asy) vector-graphics source code into rendered output (PDF, SVG, EPS, PNG, JPG) and returns it either inline (raw binary or base64 JSON) or as an object-storage URL.

AsyAgent is a proxy that wraps a local tool and exposes it as an API with optional object-storage upload for Asymptote: the asy compiler doesn't have a server mode, so asyagent wraps it in an HTTP API.

Key characteristics

• Zero third-party dependencies — pure Python 3.10+ standard library. No pip install, no virtualenv required.
• Header-driven control plane — all request behaviour (output format, response mode, encoding, DPI, timeout, storage prefix) is controlled by X-Asy-* request headers.
• Dual response modes — return compiled output inline (binary or base64 JSON) or upload to storage and return a URL.
• Multiple storage backends — local filesystem (zero-config), S3-compatible object storage (hand-rolled AWS Signature V4), or disabled.
• Multi-format — native pdf/svg/eps, plus png/jpg via Ghostscript rasterization. Multi-output (multiple shipout() calls) is auto-bundled as a ZIP.

Quick start

# Start the server (zero config — uses local storage)
python3 -m asyagent

# Compile an asy source, get PDF inline
curl -s http://127.0.0.1:8787/v1/render \
  --data-binary 'size(5cm); draw(unitcircle);' \
  -H 'Content-Type: text/plain' \
  -o circle.pdf

# Get a PNG instead
curl -s http://127.0.0.1:8787/v1/render \
  --data-binary 'size(5cm); draw(unitcircle);' \
  -H 'Content-Type: text/plain' \
  -H 'X-Asy-Format: png' \
  -o circle.png

# Return base64 JSON
curl -s http://127.0.0.1:8787/v1/render \
  -d '{"source": "size(5cm); draw(unitcircle);"}' \
  -H 'Content-Type: application/json' \
  -H 'X-Asy-Encoding: base64'

# Upload to storage, return URL
curl -s http://127.0.0.1:8787/v1/render \
  -d '{"source": "size(5cm); draw(unitcircle);"}' \
  -H 'Content-Type: application/json' \
  -H 'X-Asy-Mode: url'

API

POST /v1/render

Accepts an Asymptote source and returns the compiled output.

Request body (one of):

Body type	Content-Type	Description
Raw source text	text/plain (or any non-JSON)	The .asy source code directly. Auto-detection: if the body is a single line starting with http:// or https://, it's treated as a URL.
JSON object	application/json	{"source": "..."} or {"url": "https://..."}

Control headers:

Header	Values	Default	Description
X-Asy-Format	pdf svg eps png jpg jpeg	pdf (or inferred from Accept)	Output format
X-Asy-Mode	inline url	inline	inline = return binary/base64; url = upload to storage, return URL
X-Asy-Encoding	binary base64	binary	Only for inline mode. binary returns raw bytes with proper Content-Type; base64 returns JSON with base64-encoded data
X-Asy-Input	auto source url	auto	How to interpret a non-JSON body
X-Asy-Dpi	1–4096	150	DPI for raster formats (png/jpg)
X-Asy-Timeout	seconds	60	Compile timeout (capped by ASYAGENT_MAX_TIMEOUT)
X-Asy-Filename	string	—	Suggested filename for Content-Disposition / storage key
X-Asy-Disposition	inline attachment	inline	Content-Disposition value
X-Asy-Storage-Prefix	string	env S3_PREFIX	Override storage key prefix for this request
X-Asy-Storage-Bucket	string	env S3_BUCKET	Override S3 bucket for this request
Accept	MIME type	—	Alternative to X-Asy-Format (e.g. Accept: image/png)

Response (inline/binary): Raw bytes with Content-Type matching the format (e.g. application/pdf, image/png).

Response (inline/base64):

{
  "ok": true,
  "mode": "inline",
  "encoding": "base64",
  "format": "pdf",
  "mime": "application/pdf",
  "size": 5989,
  "data": "JVBERi0xLjU..."
}

Response (url mode):

{
  "ok": true,
  "mode": "url",
  "format": "pdf",
  "mime": "application/pdf",
  "size": 5989,
  "url": "http://host/files/...",
  "key": "files/abc123.pdf",
  "urls": [{"url": "...", "key": "...", "mime": "...", "size": 5989}]
}

GET /

Service info (version, formats, storage health, defaults).

GET /healthz

Health check — returns 200 if storage is writable, 503 otherwise.

GET /files/{key}

Serves files from local storage (only available when ASYAGENT_STORAGE=local).

Configuration

All configuration via environment variables:

Server

Variable	Default	Description
ASYAGENT_HOST	0.0.0.0	Listen address
ASYAGENT_PORT	8787	Listen port
ASYAGENT_MAX_WORKERS	16	Max concurrent compiles (semaphore)
ASYAGENT_COMPILE_TIMEOUT	60	Default compile timeout (s)
ASYAGENT_MAX_TIMEOUT	300	Max allowed client-requested timeout
ASYAGENT_FETCH_TIMEOUT	20	URL fetch timeout (s)
ASYAGENT_MAX_SOURCE_BYTES	1048576	Max request body size
ASYAGENT_MAX_FETCH_BYTES	5242880	Max remote file size for URL input
ASYAGENT_ASY_BIN	asy	Path to asy binary
ASYAGENT_GS_BIN	gs	Path to ghostscript binary
ASYAGENT_DEFAULT_FORMAT	pdf	Default output format
ASYAGENT_DEFAULT_MODE	inline	Default response mode
ASYAGENT_DEFAULT_ENCODING	binary	Default inline encoding
ASYAGENT_DEFAULT_DPI	150	Default raster DPI
ASYAGENT_TMP_DIR	—	Override temp directory for compile working dirs

Storage

Variable	Default	Description
ASYAGENT_STORAGE	local	Backend: local, s3, or none
ASYAGENT_LOCAL_DIR	./storage	Local storage directory
ASYAGENT_LOCAL_BASE_URL	auto	Base URL for local file serving

S3 / Object Storage

Variable	Default	Description
S3_BUCKET	—	Bucket name (required for S3)
S3_PREFIX	asyagent/	Key prefix
S3_ENDPOINT	auto	Custom endpoint (e.g. http://minio:9000)
S3_URL_STYLE	path	path or virtual (virtual-hosted)
S3_PUBLIC_BASE_URL	—	Override the public URL base (e.g. CDN domain)
S3_PRESIGN	false	Return presigned URLs instead of public URLs
S3_PRESIGN_EXPIRES	3600	Presigned URL expiry (s)
S3_USE_TLS	true	Use HTTPS for S3 API calls
AWS_ACCESS_KEY_ID	—	Access key
AWS_SECRET_ACCESS_KEY	—	Secret key
AWS_SESSION_TOKEN	—	STS session token (optional)
AWS_REGION	us-east-1	Region

Architecture

asyagent/
  __init__.py          # package metadata
  __main__.py          # python -m asyagent entry point
  config.py            # Settings dataclass, env-driven
  errors.py            # typed exception hierarchy
  sigv4.py             # AWS Signature V4 (sign + presign), zero-dep
  fetcher.py           # URL -> source text fetcher
  compiler.py          # asy invocation + gs rasterization + ZIP bundling
  storage.py           # Local / S3 / None storage backends
  server.py            # ThreadingHTTPServer, header-driven rendering
tests/
  test_sigv4.py        # KAT against AWS test vector (AKIDEXAMPLE)
  test_compiler.py     # all formats, multi-shipout, errors
  test_server.py       # end-to-end integration tests
examples/
  unit_circle.asy      # example source
  function_plot.asy    # example source
  multi_page.asy       # multi-shipout example
  client.py            # example client script

Request flow

Client ──POST /v1/render──▶ server.py
  │                           │
  │  Headers: X-Asy-Format,   │  RenderContext (parses all X-Asy-* headers)
  │  X-Asy-Mode, etc.         │
  │                           ├── text/plain body ──▶ _resolve_source (auto-detect url/source)
  │                           ├── application/json ──▶ _resolve_source (json.source or json.url)
  │                           │                          └── fetcher.py (if url)
  │                           │
  │                           ├── compile_source (semaphore-gated)
  │                           │   ├── asy -f pdf -o out input.asy    (native: pdf/svg/eps)
  │                           │   ├── gs -sDEVICE=pngalpha ...        (raster: png/jpg)
  │                           │   └── select_or_bundle (ZIP if multiple outputs)
  │                           │
  │                           ├── mode=inline,encoding=binary ──▶ raw bytes + Content-Type
  │                           ├── mode=inline,encoding=base64 ──▶ JSON {data: base64...}
  │                           └── mode=url ──▶ storage.upload ──▶ JSON {url: ...}
  │
◀── response (binary / JSON) ─┘

Response mode comparison

Mode	Encoding	Response body	Content-Type	Use case
inline	binary	Raw compiled bytes	matches format	Direct download, browser display
inline	base64	JSON {data: "..."}	application/json	API compositing, embedding in JSON workflows
url	—	JSON {url: "..."}	application/json	Large files, CDN delivery, async workflows

Running tests

python3 -m unittest discover -s tests -v

Docker

docker build -t asyagent .
docker run -p 8787:8787 asyagent

License

MIT