pulumi/pulumi · warning

no go.mod file found: %v

Error message

no go.mod file found: %v

What it means

`go list -m -f {{.GoMod}}` can exit 0 while printing nothing when the program is not in a Go module. loadGomod detects the empty output and raises this error naming the program directory. Like the go list -m error, GetRequiredPackages catches it upstream, logs it, and continues with no required packages.

Source

Thrown at sdk/go/pulumi-language-go/main.go:758

	//		GoMod    string // path to go.mod file
	//	}
	//
	// See 'go help list' for the full definition.
	cmd := exec.Command(gobin, "list", "-m", "-f", "{{.GoMod}}")
	// Disable GOWORK, we only want the one module found in this (or a parent) directory. Workspaces being
	// enabled will cause "list -m" to list every module in the workspace.
	cmd.Env = append(os.Environ(), "GOWORK=off")
	cmd.Dir = programDir
	cmd.Stderr = os.Stderr
	out, err := cmd.Output()
	if err != nil {
		return "", nil, fmt.Errorf("go list -m: %w", err)
	}
	out = bytes.TrimSpace(out)
	if len(out) == 0 {
		// The 'go list' command above will exit successfully
		// and return no output if the program is not in a Go module.
		return "", nil, fmt.Errorf("no go.mod file found: %v", programDir)
	}

	modPath := string(out)
	body, err := os.ReadFile(modPath)
	if err != nil {
		return "", nil, err
	}

	f, err := modfile.Parse(modPath, body, nil)
	if err != nil {
		return "", nil, fmt.Errorf("parse: %w", err)
	}

	return filepath.Dir(modPath), f, nil
}

// GetRequiredPackages computes the complete set of anticipated packages required by a program.
// We're lenient here as this relies on the `go list` command and the use of modules.

View on GitHub (pinned to 793f7b2e16)

Solutions

1. Run `go mod init github.com/you/myprogram` in the program directory (the one named in the error).
2. Verify Pulumi.yaml's `main:` points at the directory containing go.mod (or a subdir of it).
3. Ensure go.mod is committed/copied in CI and present in the working directory used by `pulumi up`.
4. Run `go list -m -f {{.GoMod}}` in that directory to confirm a path is printed before deploying.

Example fix

// before: program dir without go.mod
$ cd myprogram && pulumi up
// after
cd myprogram
go mod init example.com/myprogram
go mod tidy
pulumi up

// shell: ensure the deploy dir resolves to a go.mod
test -f go.mod || { echo "run go mod init in $(pwd)"; exit 1; }

// empty output from `go list -m -f {{.GoMod}}` means not-in-module; treat as setup error
if len(bytes.TrimSpace(out)) == 0 {
    return fmt.Errorf("no go.mod file found: %v — run `go mod init` in the program dir", programDir)
}

When it happens

Trigger: GetRequiredPackages -> loadGomod: `go list -m` succeeds but prints no GoMod path because programDir (req.Info.ProgramDirectory) is outside any module.

Common situations: Running a Pulumi Go program directory that never got `go mod init`; pointing main at the wrong folder via `main:` in Pulumi.yaml; CI checkout that excludes go.mod; GOPATH-mode projects migrated from older tooling.

Related errors

• go list -m: %w
• parse: %w
• language did not return handshake response, attaching via an
• illegal semver returned by language host: %s@%s: %w
• unrecognized plugin kind: %s

AI-assisted analysis of pulumi/pulumi@793f7b2e16 (2026-08-31). Data as JSON: /api/errors/468719eb7cb23cea. Report an issue: GitHub.