feat(check): report kernel version and fs type

stacker functionality depends on kernel versions and filesystem support.
So useful to report this often, at least to debug issues.

Signed-off-by: Ramkumar Chinchani <rchincha@cisco.com>

cmd/stacker/check.go

@@ -8,7 +8,9 @@ import (
 	"github.com/pkg/errors"
 	"github.com/pkg/xattr"
 	"github.com/urfave/cli"
+	"stackerbuild.io/stacker/pkg/log"
 	"stackerbuild.io/stacker/pkg/overlay"
+	"stackerbuild.io/stacker/pkg/stacker"
 )
 
 var checkCmd = cli.Command{
@@ -18,6 +20,21 @@ var checkCmd = cli.Command{
 }
 
 func doCheck(ctx *cli.Context) error {
+
+	kernel, err := stacker.KernelInfo()
+	if err != nil {
+		return errors.Wrapf(err, "couldn't get kernel info")
+	}
+
+	log.Infof(kernel)
+
+	fstype, err := stacker.MountInfo(config.RootFSDir)
+	if err != nil {
+		return errors.Wrapf(err, "couldn't get fs type")
+	}
+
+	log.Infof("%s %s", config.RootFSDir, fstype)
+
 	if err := os.MkdirAll(config.RootFSDir, 0700); err != nil {
 		return errors.Wrapf(err, "couldn't create rootfs dir for testing")
 	}

pkg/stacker/check.go

@@ -0,0 +1,114 @@
+package stacker
+
+import (
+	"fmt"
+
+	"golang.org/x/sys/unix"
+)
+
+func KernelInfo() (string, error) {
+	utsname := unix.Utsname{}
+	if err := unix.Uname(&utsname); err != nil {
+		return "", err
+	}
+
+	return fmt.Sprintf("%s %s %s", string(utsname.Sysname[:]), string(utsname.Release[:]), string(utsname.Version[:])), nil
+}
+
+func MountInfo(path string) (string, error) {
+	// from /usr/include/linux/magic.h
+	var fstypeMap = map[int64]string{
+		0xadf5:     "ADFS",
+		0xadff:     "AFFS",
+		0x5346414F: "AFS",
+		0x0187:     "AUTOFS",
+		0x73757245: "CODA",
+		0x28cd3d45: "CRAMFS",
+		0x453dcd28: "CRAMFS_WEND",
+		0x64626720: "DEBUGFS",
+		0x73636673: "SECURITYFS",
+		0xf97cff8c: "SELINUX",
+		0x43415d53: "SMACK",
+		0x858458f6: "RAMFS",
+		0x01021994: "TMPFS",
+		0x958458f6: "HUGETLBFS",
+		0x73717368: "SQUASHFS",
+		0xf15f:     "ECRYPTFS",
+		0x414A53:   "EFS",
+		0xE0F5E1E2: "EROFS_V1",
+		0xEF53:     "EXT2",
+		0xabba1974: "XENFS",
+		0x9123683E: "BTRFS",
+		0x3434:     "NILFS",
+		0xF2F52010: "F2FS",
+		0xf995e849: "HPFS",
+		0x9660:     "ISOFS",
+		0x72b6:     "JFFS2",
+		0x58465342: "XFS	",
+		0x6165676C: "PSTOREFS	",
+		0xde5e81e4: "EFIVARFS	",
+		0x00c0ffee: "HOSTFS",
+		0x794c7630: "OVERLAYFS",
+		0x137F:     "MINIX",
+		0x138F:     "MINIX2",
+		0x2468:     "MINIX2",
+		0x2478:     "MINIX22",
+		0x4d5a:     "MINIX3",
+		0x4d44:     "MSDOS",
+		0x564c:     "NCP",
+		0x6969:     "NFS",
+		0x7461636f: "OCFS2",
+		0x9fa1:     "OPENPROM",
+		0x002f:     "QNX4",
+		0x68191122: "QNX6",
+		0x6B414653: "AFS_FS	",
+		0x52654973: "REISERFS",
+		0x517B:     "SMB",
+		0x27e0eb:   "CGROUP",
+		0x63677270: "CGROUP2",
+		0x7655821:  "RDTGROUP",
+		0x57AC6E9D: "STACK_END",
+		0x74726163: "TRACEFS",
+		0x01021997: "V9FS",
+		0x62646576: "BDEVFS",
+		0x64646178: "DAXFS",
+		0x42494e4d: "BINFMTFS",
+		0x1cd1:     "DEVPTS",
+		0x6c6f6f70: "BINDERFS",
+		0xBAD1DEA:  "FUTEXFS",
+		0x50495045: "PIPEFS",
+		0x9fa0:     "PROC",
+		0x534F434B: "SOCKFS",
+		0x62656572: "SYSFS",
+		0x9fa2:     "USBDEVICE",
+		0x11307854: "MTD_INODE_FS",
+		0x09041934: "ANON_INODE_FS",
+		0x73727279: "BTRFS_TEST",
+		0x6e736673: "NSFS",
+		0xcafe4a11: "BPF_FS",
+		0x5a3c69f0: "AAFS",
+		0x5a4f4653: "ZONEFS",
+		0x15013346: "UDF",
+		0x13661366: "BALLOON_KVM",
+		0x58295829: "ZSMALLOC",
+		0x444d4142: "DMA_BUF",
+		0x454d444d: "DEVMEM",
+		0x33:       "Z3FOLD",
+		0xc7571590: "PPC_CMM",
+		0x5345434d: "SECRETMEM",
+		0x6a656a62: "SHIFTFS",
+	}
+
+	st := unix.Statfs_t{}
+	if err := unix.Statfs(path, &st); err != nil {
+		return "", err
+	}
+
+	fstype, ok := fstypeMap[st.Type]
+	if !ok {
+		fstype = "unknown"
+	}
+
+	// lookup fs type in /usr/include/linux/magic.h
+	return fmt.Sprintf("%s(%x)", fstype, st.Type), nil
+}