Verify /etc/os-release contents

main.go

package main

import (
	"fmt"
	"log"
	"os"
	"path/filepath"

	"github.com/ashcrow/osrelease"
	"github.com/davecgh/go-spew/spew"
	"github.com/openshift/machine-config-operator/pkg/daemon"
)

func getNodeRunningOS(etcPath, libPath string) (daemon.OperatingSystem, error) {
	ret := daemon.OperatingSystem{}

	or, err := osrelease.NewWithOverrides(etcPath, libPath)
	if err != nil {
		return ret, err
	}

	ret.ID = or.ID
	ret.VariantID = or.VARIANT_ID
	ret.VersionID = or.VERSION_ID

	return ret, nil
}

func analyzeOSRelease(osReleaseContents string) error {
	tmpDir := os.TempDir()
	defer os.RemoveAll(tmpDir)

	osReleasePath := filepath.Join(tmpDir, "etc-os-release")
	libReleasePath := filepath.Join(tmpDir, "usr-lib-os-release")

	if err := os.WriteFile(osReleasePath, []byte(osReleaseContents), 0644); err != nil {
		return err
	}

	if err := os.WriteFile(libReleasePath, []byte(osReleaseContents), 0644); err != nil {
		return err
	}

	os, err := getNodeRunningOS(osReleasePath, libReleasePath)
	if err != nil {
		return err
	}

	spew.Dump(os)

	fmt.Printf("IsEL(): %v\n", os.IsEL())
	fmt.Printf("IsEL9(): %v\n", os.IsEL9())
	fmt.Printf("IsFCOS(): %v\n", os.IsFCOS())
	fmt.Printf("IsSCOS(): %v\n", os.IsSCOS())
	fmt.Printf("IsCoreOSVariant(): %v\n", os.IsCoreOSVariant())
	fmt.Printf("IsLikeTraditionalRHEL7(): %v\n", os.IsLikeTraditionalRHEL7())
	fmt.Printf("ToPrometheusLabel(): %s\n", os.ToPrometheusLabel())

	return nil
}

func main() {
	osReleaseContents := `NAME="Red Hat Enterprise Linux CoreOS"
ID="rhcos"
ID_LIKE="rhel fedora"
VERSION="412.86.202301311551-0"
VERSION_ID="4.12"
PLATFORM_ID="platform:el8"
PRETTY_NAME="Red Hat Enterprise Linux CoreOS 412.86.202301311551-0 (Ootpa)"
ANSI_COLOR="0;31"
CPE_NAME="cpe:/o:redhat:enterprise_linux:8::coreos"
HOME_URL="https://www.redhat.com/"
DOCUMENTATION_URL="https://docs.openshift.com/container-platform/4.12/"
BUG_REPORT_URL="https://access.redhat.com/labs/rhir/"
REDHAT_BUGZILLA_PRODUCT="OpenShift Container Platform"
REDHAT_BUGZILLA_PRODUCT_VERSION="4.12"
REDHAT_SUPPORT_PRODUCT="OpenShift Container Platform"
REDHAT_SUPPORT_PRODUCT_VERSION="4.12"
OPENSHIFT_VERSION="4.12"
RHEL_VERSION="8.6"
OSTREE_VERSION="412.86.202301311551-0"`

	if err := analyzeOSRelease(osReleaseContents); err != nil {
		log.Fatal(err)
	}
}