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The Go pack builds a static Linux binary from your go.mod and serves it on a scratch base image. No runtime dependencies, fast cold starts, small images.

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When it runs

Raypacks picks the Go pack when both are true:
  1. There’s a go.mod at the repo root.
  2. There’s a main.go either at the root or under cmd/<name>/main.go.
Library-only repos (no main.go anywhere) fall through detection. They’re not deployable as a Frame.

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Entrypoint resolution

Raypacks figures out what to build, in this order:
  1. [build].entrypoint in nubo.toml
  2. --entrypoint passed at build time (local rp CLI only)
  3. Auto-detection: ./main.go at the root, then the first cmd/<name>/main.go (alphabetical)
--entrypoint is a flag for the local rp CLI. Managed Nubo builds never pass it, so on the platform the entrypoint comes from nubo.toml [build].entrypoint (or the dashboard override) or auto-detection. Pin it in nubo.toml when you have more than one candidate.
The plan table shows which won:
If you have multiple cmd/*/main.go and don’t pin a choice, the alphabetically first one wins. Pin the right one with nubo.toml:
nubo.toml

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What the build does

Environment baked in:
  • CGO_ENABLED=0
  • GOOS=linux
  • GOARCH=amd64
The resulting binary lands at /app/server in the final image with mode 0755.

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Runtime

Your binary should listen on :$PORT and 0.0.0.0. The default net/http listener http.ListenAndServe(":8080", nil) works as long as the Frame’s configured port matches 8080.

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Go version

The builder image pins Go 1.25. That’s currently fixed; we don’t yet read go 1.x directives from your go.mod.

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Limits today

  • linux/amd64 only. No ARM yet.
  • No vendor/ mode. Run go mod tidy and check go.mod/go.sum into the repo.
  • No go.work workspaces.
  • No build tags or -ldflags customization.
If any of these block you, switch the Frame’s Builder to Paketo for now and tell us what you need: support@withnubo.com.

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Common errors

go.mod detected but no main.go found at root or under cmd/*: your repo is a library, or main.go lives somewhere Raypacks doesn’t look. Add a nubo.toml entry pointing at the right directory. go build fails with “package . is not a main package”: you set an entrypoint to a directory that has Go code but no package main in it. Point at the directory that actually contains the main() function.

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Examples

A single-binary repo with main.go at the root: no config needed. A monorepo with cmd/api/main.go and cmd/worker/main.go: one Frame per binary, each with its own nubo.toml (or use the dashboard’s entrypoint override).