Go env: Troubleshoot Missing C Compiler

Problem

When build the project locally, the following errors occured

$ make build
# github.com/neuvector/neuvector/controller/common
../go/pkg/mod/github.com/neuvector/neuvector@v0.0.0-20250903232727-c2d83d9df18f/controller/common/output.go:55:13: undefined: LevelToPrio
../go/pkg/mod/github.com/neuvector/neuvector@v0.0.0-20250903232727-c2d83d9df18f/controller/common/output.go:92:14: undefined: LevelToPrio
# ... more undefined errors

This build works fine in CI and other Linux environments, but fails locally.

Environment

- OS: Ubuntu 24.04.1 LTS (x86_64)
- Architecture: x86_64
- RKE2: v1.33.0+rke2r1
- go: go1.24.2

Root Cause Analysis

• Ubuntu version: Same as CI → not the cause
• RKE2 version: Unrelated to local build
• Go version: Same as CI → not the cause
• Go environment: Potential cause

To inspect the Go environment, run:

go env -> check all of the var
go env CGO_ENABLED GOPROXY GOSUMDB GOOS GOARCH

Key Difference Found

Upon comparing with the CI environment, this stood out:

Fixes

Problem 1: CGO_ENABLED=0

Some Go modules rely on CGO for system-level functionality. If CGO is disabled, files using import "C" are skipped during compilation, leading to undefined symbols.

Solution:

export CGO_ENABLED=1
make build

Problem 2: Missing C Compiler

After enabling CGO, you might hit this error:

# runtime/cgo
cgo: C compiler "cc" not found: exec: "cc": executable file not found in $PATH

Solution: Install a C compiler

sudo apt update
sudo apt install build-essential

This provides the required C toolchain (gcc, cc, make, etc.).

Summary

• Using go env was the key to identifying the environment difference.
• The root cause of the build failure was a mismatch in the CGO_ENABLED setting and a missing C compiler. By aligning the local environment with CI (enabling CGO and installing build tools), the issue was resolved.