Go

Summary

Item	Value
API name	go
source OCI image	golang:1.25-alpine
per-job resource ceiling	2 vCPU, 1024 MiB

The vCPU and RAM ceiling exists to prevent abuse; libkrun memory is elastic and the host only pays for what the guest touches.

Warmup

The build compiles a program with GOCACHE=/opt/runner/gocache, which populates the standard library build cache inside the image. Since the root is read-only, start.sh copies that cache to /tmp/go-cache at boot, the path the guest executor forces into GOCACHE. The copy happens before the VM enters the pool and does not weigh on the job. Measured: go run in 247 ms with the warm cache, versus 3.4 s without it.

See Images.

How the code is executed

The main file (the first in files) is executed with go run <file>. With no network, only the standard library is available: external modules are not downloaded. Everything runs in a directory under /tmp (tmpfs), in a fresh VM destroyed at the end of the job.

Building the image

rc image build --stack go

Example

curl -s http://127.0.0.1:8080/api/v1/run \
  -H 'Content-Type: application/json' \
  -d '{
    "language": "go",
    "files": [
      {"name": "main.go", "content": "package main\n\nimport \"fmt\"\n\nfunc main() {\n\tfmt.Println(6 * 7)\n}\n"}
    ]
  }'

Expected stdout: 42.