Job request

Format

The host converts the HTTP request (or the CLI call) into a job and sends it to the guest as a vsock frame (4 big-endian bytes of length + JSON).

{
  "trace_id": "tr-123",
  "lang": "python",
  "code": "",
  "files": [
    {"name": "main.py", "content": "import util\nprint(util.dobro(int(input())))"},
    {"name": "util.py", "content": "def dobro(x):\n    return 2 * x\n"}
  ],
  "stdin": "21",
  "timeout": 10
}

Fields

Field	Type	Description
trace_id	string	job identifier, returned in the result
lang	string	language; it must exist in the guest executor
code	string	code of the main file when there are no files
files	list of {name, content}	the job's files; the first one is the main file
stdin	string	standard input; omitted when empty
timeout	integer	seconds
stream	boolean	asks for the output in chunks before the result; see Streaming
op	string	operation; empty means the code job. The machine operations (exec, put, pty...) are in vsock protocol

Main file

• With files, each file is written by name to a temporary directory under /tmp, and the first one is executed (or compiled).
• With only code, the guest writes script.<ext> — except Java, which becomes Main.java, because the executed class is Main.

Rules applied before the job reaches the guest

The domain, on the host, rejects the job (HTTP 400 in the API) when:

Rule	Limit
language	in the catalog and with an image built on this host (otherwise E006)
stdin	≤ 1,000,000 bytes (otherwise E005)
timeout	> 0 and ≤ 300 s; missing becomes 10 s
content	code or at least one file
files	up to 32, no repeated names
total size	sum of code and contents ≤ 4 MiB
file name	no /, no .., not starting with ., ≤ 255 bytes

The name rules prevent writes outside the job directory inside the guest, even though the VM is disposable.

Readiness

Before the first real job, the host repeatedly sends the VM an sh true job (every 1 ms) until it gets a response. That is how it knows the guest is already listening.