BusyBox/Alpine support (k0sproject#94)

The BusyBox stat and touch binaries differ from their GNU counterparts
in some ways that are relevant to rig:

The stat binary won't accept the --printf flag, but it accepts the
-c flag in the same way GNU stat does. The -c command won't accept
backslash escapes, though. Hence fall back to the pipe character as
delimiter.

The touch binary won't parse time zones and sub-second precision times.
Accommodate for that by normalizing the time to UTC and only use sub-
second precision timestamps if it's not BusyBox touch. This will loose
precision, but that's probably better than failing completely.

Make localhost connections use the SHELL instead of hard-coding bash.
Make the rigfs helper shell script POSIX compatible.

Add an OS support package for Alpine that uses apk for package
installations.

Add a minimal footloose-compatible Dockerfile for Alpine 3.18 to the
tests and execute it as part of the CI.

.github/workflows/go.yml

@@ -34,13 +34,15 @@ jobs:
 
   integration:
     strategy:
+      fail-fast: false
       matrix:
         image:
           - quay.io/footloose/ubuntu18.04
           - quay.io/footloose/centos7
           # - quay.io/footloose/amazonlinux2  ( not recognized )
           - quay.io/footloose/debian10
           # - quay.io/footloose/fedora29 ( not recognized )
+          - alpine-3.18.iid
     needs: build
     runs-on: ubuntu-20.04
     steps:
@@ -57,8 +59,21 @@ jobs:
         sudo apt-get update
         sudo apt-get install expect
 
+    - name: Prepare footloose image
+      id: prepare-footloose-image
+      env:
+        IMAGE: ${{ matrix.image }}
+      run: |
+        case "$IMAGE" in
+        *.iid)
+          make -C test "$IMAGE"
+          IMAGE="$(cat "test/$IMAGE")"
+          ;;
+        esac
+        echo image="$IMAGE" >> $GITHUB_OUTPUT
+
     - name: Run integration tests
       env:
-        LINUX_IMAGE: ${{ matrix.image }}
+        LINUX_IMAGE: ${{ steps.prepare-footloose-image.outputs.image }}
       run: make -C test test
 

.gitignore

@@ -2,3 +2,4 @@ test/rigtest
 test/footloose.yaml
 test/Library
 test/.ssh
+test/*.iid

cmd/rigtest/rigtest.go

@@ -22,6 +22,7 @@ import (
 	_ "github.com/k0sproject/rig/os/support"
 	"github.com/k0sproject/rig/pkg/rigfs"
 	"github.com/kevinburke/ssh_config"
+	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
 
@@ -59,6 +60,7 @@ type configurer interface {
 	FileExist(os.Host, string) bool
 	DeleteFile(os.Host, string) error
 	Stat(os.Host, string, ...exec.Option) (*os.FileInfo, error)
+	Touch(os.Host, string, time.Time, ...exec.Option) error
 	MkDir(os.Host, string, ...exec.Option) error
 }
 
@@ -218,6 +220,22 @@ func main() {
 
 		t.Run("os support module functions on %s", h)
 
+		stat, err := h.Configurer.Stat(h, fn)
+		require.Error(t, err, "no stat error")
+
+		now := time.Now()
+		err = h.Configurer.Touch(h, fn, now)
+		require.NoError(t, err, "touch error")
+
+		stat, err = h.Configurer.Stat(h, fn)
+		require.NoError(t, err, "stat error")
+		assert.Equal(t, filepath.Base(stat.Name()), filepath.Base(fn), "stat name not as expected")
+		assert.Equal(t, filepath.Base(stat.Name()), filepath.Base(fn), "stat name not as expected")
+		assert.Condition(t, func() bool {
+			actual := stat.ModTime()
+			return now.Equal(actual) || now.Truncate(time.Second).Equal(actual)
+		}, "Expected %s, got %s", now, stat.ModTime())
+
 		require.NoError(t, h.Configurer.WriteFile(h, fn, "test\ntest2\ntest3", "0644"), "write file")
 		if !h.Configurer.FileExist(h, fn) {
 			t.Fail("file does not exist after write")
@@ -228,10 +246,6 @@ func main() {
 		require.NoError(t, err, "read file")
 		require.Equal(t, "test\ntest4\ntest3", row, "file content not as expected after line into file")
 
-		stat, err := h.Configurer.Stat(h, fn)
-		require.NoError(t, err, "stat error")
-		require.Equal(t, filepath.Base(stat.Name()), filepath.Base(fn), "stat name not as expected")
-
 		require.NoError(t, h.Configurer.DeleteFile(h, fn))
 		require.False(t, h.Configurer.FileExist(h, fn))
 

localhost.go

@@ -156,7 +156,7 @@ func (c *Localhost) command(cmd string, o *exec.Options) (*osexec.Cmd, error) {
 		return osexec.Command("cmd.exe", "/c", cmd), nil
 	}
 
-	return osexec.Command("bash", "-c", "--", cmd), nil
+	return osexec.Command("sh", "-c", "--", cmd), nil
 }
 
 // ExecInteractive executes a command on the host and copies stdin/stdout/stderr from local host

os/linux.go

@@ -406,16 +406,26 @@ func (c Linux) Chmod(h Host, s, perm string, opts ...exec.Option) error {
 // coreutils. Note that this is different from BSD coreutils.
 const gnuCoreutilsDateTimeLayout = "2006-01-02 15:04:05.999999999 -0700"
 
+// busyboxDateTimeLayout represents the date and time format that can be passed
+// to BusyBox. BusyBox will happily output the GNU format, but will fail to
+// parse it. Currently, there doesn't seem to be a way to support sub-second
+// precision.
+const busyboxDateTimeLayout = "2006-01-02 15:04:05"
+
 // Stat gets file / directory information
 func (c Linux) Stat(h Host, path string, opts ...exec.Option) (*FileInfo, error) {
-	cmd := `env -i LC_ALL=C stat --printf '%s\0%y\0%a\0%F' -- ` + shellescape.Quote(path)
+	cmd := `env -i LC_ALL=C stat -c '%s|%y|%a|%F' -- ` + shellescape.Quote(path)
 
 	out, err := h.ExecOutput(cmd, opts...)
 	if err != nil {
 		return nil, fmt.Errorf("failed to stat %s: %w", path, err)
 	}
 
-	fields := strings.SplitN(out, "\x00", 4)
+	fields := strings.SplitN(out, "|", 4)
+	if len(fields) != 4 {
+		err = fmt.Errorf("failed to stat %s: unrecognized output: %s", path, out) //nolint:goerr113
+		return nil, err
+	}
 
 	size, err := strconv.ParseInt(fields[0], 10, 64)
 	if err != nil {
@@ -444,8 +454,24 @@ func (c Linux) Stat(h Host, path string, opts ...exec.Option) (*FileInfo, error)
 // Touch updates a file's last modified time. It creates a new empty file if it
 // didn't exist prior to the call to Touch.
 func (c Linux) Touch(h Host, path string, ts time.Time, opts ...exec.Option) error {
-	cmd := fmt.Sprintf("env -i LC_ALL=C touch -m -d %s -- %s",
-		shellescape.Quote(ts.Format(gnuCoreutilsDateTimeLayout)),
+	utc := ts.UTC()
+
+	// The BusyBox format will be accepted by both BusyBox and GNU stat.
+	format := busyboxDateTimeLayout
+
+	// Sub-second precision in timestamps is supported by GNU, but not by
+	// BusyBox. If there is sub-second precision in the provided timestamp, try
+	// to detect BusyBox touch and if it's not BusyBox go on with the
+	// full-precision GNU format instead.
+	if !utc.Equal(utc.Truncate(time.Second)) {
+		out, err := h.ExecOutput("env -i LC_ALL=C TZ=UTC touch --help 2>&1")
+		if err != nil || !strings.Contains(out, "BusyBox") {
+			format = gnuCoreutilsDateTimeLayout
+		}
+	}
+
+	cmd := fmt.Sprintf("env -i LC_ALL=C TZ=UTC touch -m -d %s -- %s",
+		shellescape.Quote(utc.Format(format)),
 		shellescape.Quote(path),
 	)
 

os/linux/alpine.go

@@ -0,0 +1,52 @@
+package linux
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/alessio/shellescape"
+	"github.com/k0sproject/rig"
+	"github.com/k0sproject/rig/exec"
+	"github.com/k0sproject/rig/os"
+	"github.com/k0sproject/rig/os/registry"
+)
+
+// Alpine provides OS support for Alpine Linux.
+type Alpine struct {
+	os.Linux
+}
+
+func init() {
+	registry.RegisterOSModule(
+		func(os rig.OSVersion) bool {
+			return os.ID == "alpine"
+		},
+		func() interface{} {
+			return &Alpine{}
+		},
+	)
+}
+
+// InstallPackage installs packages via apk.
+func (l Alpine) InstallPackage(host os.Host, pkgs ...string) error {
+	if err := host.Execf("apk update", exec.Sudo(host)); err != nil {
+		return fmt.Errorf("failed to update apk cache: %w", err)
+	}
+
+	if len(pkgs) < 1 {
+		return nil
+	}
+
+	var cmd strings.Builder
+	cmd.WriteString("apk add --")
+	for _, pkg := range pkgs {
+		cmd.WriteRune(' ')
+		cmd.WriteString(shellescape.Quote(pkg))
+	}
+
+	if err := host.Exec(cmd.String(), exec.Sudo(host)); err != nil {
+		return fmt.Errorf("failed to install apk packages: %w", err)
+	}
+
+	return nil
+}

pkg/rigfs/posixfsys.go

@@ -19,7 +19,7 @@ import (
 // rigHelper is a helper script to avoid having to write complex bash oneliners in Go
 // it's not a read-loop "daemon" like the windows counterpart rigrcp.ps1
 //
-//go:embed righelper.bash
+//go:embed righelper.sh
 var rigHelper string
 
 var (
@@ -278,7 +278,7 @@ func (fsys *PosixFsys) helper(args ...string) (*helperResponse, error) {
 	var res helperResponse
 	opts := fsys.opts
 	opts = append(opts, exec.Stdin(rigHelper))
-	out, err := fsys.conn.ExecOutput(fmt.Sprintf("bash -s -- %s", shellescape.QuoteCommand(args)), opts...)
+	out, err := fsys.conn.ExecOutput(fmt.Sprintf("sh -s -- %s", shellescape.QuoteCommand(args)), opts...)
 	if err != nil {
 		return nil, fmt.Errorf("%w: failed to execute helper: %w", ErrCommandFailed, err)
 	}

pkg/rigfs/righelper.bash → pkg/rigfs/righelper.sh

@@ -1,6 +1,5 @@
-#!/usr/bin/env bash
-
-shopt -s dotglob
+#!/usr/bin/env sh
+#shellcheck disable=SC3037,SC3043
 
 abs() (
   if [ -d "$1" ]; then
@@ -26,12 +25,12 @@ statjson() {
   if [ "$path" = "" ]; then
     throw "empty path"
   fi
-  if stat --help 2>&1 | grep -q -- --format; then
-    # GNU stat
-    file_info=$(stat --format="0%a %s %Y" "$path" 2> /dev/null)
+  if stat --help 2>&1 | grep -q -- 'GNU\|BusyBox'; then
+    # GNU/BusyBox stat
+    file_info=$(stat -c '0%a %s %Y' -- "$path" 2> /dev/null)
   else
     # BSD stat
-    file_info=$(stat -f "%Mp%Lp %z %m" "$path" 2> /dev/null)
+    file_info=$(stat -f '%Mp%Lp %z %m' "$path" 2> /dev/null)
   fi
   read -r unix_mode size mod_time <<EOF
 $file_info
@@ -44,15 +43,15 @@ EOF
   else
     is_dir=false
   fi
-  if [ "$embed" == "" ]; then
+  if [ -z "$embed" ]; then
     echo -n "{\"stat\":{\"size\":$size,\"unixMode\":$unix_mode,\"modTime\":$mod_time,\"isDir\":$is_dir,\"name\":\"$path\"}}"
   else
     echo -n "{\"size\":$size,\"unixMode\":$unix_mode,\"modTime\":$mod_time,\"isDir\":$is_dir,\"name\":\"$path\"}"
   fi
 }
 
 throw() {
-  echo -n "{\"error\":\"$@\"}"
+  echo -n "{\"error\":\"$*\"}"
   exit 1
 }
 
@@ -88,7 +87,8 @@ main() {
       fi
       echo -n "{\"dir\":["
       first=true
-      for file in "$path"/*; do
+      for file in "$path"/.* "$path"/*; do
+        case "$file" in "$path"/. | "$path"/..) continue ;; esac
         if [ "$first" = true ]; then
           first=false
         else
@@ -113,4 +113,5 @@ main() {
       ;;
   esac
 }
-main $@
+
+main "$@"

test/Dockerfile.alpine-3.18

@@ -0,0 +1,13 @@
+FROM docker.io/library/alpine:3.18.3
+
+RUN apk add --no-cache \
+  alpine-base \
+  openssh-server \
+  bash \
+  && rc-update add syslog boot \
+  && rc-update add sshd default \
+  && rc-update add local default \
+# disable ttys
+  && sed -i -e 's/^\(tty[0-9]\)/# \1/' /etc/inittab \
+# no greetings
+  && truncate -c -s0 /etc/issue /etc/motd

test/Makefile

@@ -52,6 +52,9 @@ footloose.yaml: .ssh/identity $(footloose)
     --override \
 		--replicas $(REPLICAS)
 
+%.iid: Dockerfile.%
+	docker build --iidfile '$@' - < '$<'
+
 .PHONY: create-host
 create-host: footloose.yaml docker-network
 	$(footloose) create -c footloose.yaml
@@ -63,7 +66,7 @@ delete-host: footloose.yaml
 .PHONY: clean
 clean: delete-host
 	rm -f footloose.yaml identity rigtest
-	rm -rf .ssh
+	rm -rf .ssh *.iid
 	docker network rm footloose-cluster || true
 
 .PHONY: sshport