Adds statik tool for development and debugging

You can run the included statik tool to determine what is being stored in statik files. This can be helpful to compare against what is in the files for other versions, like when git is detecting a change but that's unexpected.

Signed-off-by: Daniel Mikusa <[email protected]>

cmd/statik/main.go

@@ -0,0 +1,85 @@
+package main
+
+import (
+	"fmt"
+	"io/ioutil"
+	"os"
+	"sort"
+	"time"
+
+	_ "github.com/paketo-buildpacks/pipeline-builder/octo/statik"
+	"github.com/rakyll/statik/fs"
+)
+
+// Prints the contents of all the statik files as well as their names and modification times
+//
+// This can be useful to see what has changed between two versions.
+//
+// For example:
+//   1. `git co <branch>`
+//   2. `go run cmd/statik/main.go > old.txt`
+//   3. `git co <other-branch>`
+//   4. `go run cmd/statik/main.go > new.txt`
+//   5. `diff -u old.txt new.txt`
+func main() {
+	fmt.Println("Contents of statik files")
+	fmt.Println()
+
+	statik, err := fs.New()
+	if err != nil {
+		fmt.Println(err)
+		panic("unable to open static fs")
+	}
+
+	maxLen := 0
+	files := []string{}
+	data := map[string]time.Time{}
+	err = fs.Walk(statik, "/", func(path string, info os.FileInfo, err error) error {
+		if err != nil {
+			return fmt.Errorf("unable to walk\n%w", err)
+		}
+
+		_, ok := data[path]
+		if ok {
+			return fmt.Errorf("unable to continue, duplicate file %s", path)
+		}
+
+		if len(path) > maxLen {
+			maxLen = len(path)
+		}
+		files = append(files, path)
+		data[path] = info.ModTime()
+
+		fmt.Println()
+		fmt.Println("#########################################", path)
+
+		fp, err := statik.Open(path)
+		if err != nil {
+			return fmt.Errorf("unable to open file %s", path)
+		}
+
+		b, err := ioutil.ReadAll(fp)
+		if err != nil {
+			return fmt.Errorf("unable to read file %s", path)
+		}
+
+		fmt.Println(string(b))
+
+		return nil
+	})
+	if err != nil {
+		fmt.Println(err)
+		panic("unable to walk statik fs")
+	}
+	fmt.Println()
+	fmt.Println("Listing files & modification times stored in statik")
+
+	sort.Strings(files)
+	for _, path := range files {
+		gap := ""
+		for i := 0; i < maxLen-len(path); i++ {
+			gap += " "
+		}
+		fmt.Printf("%s  %s  %s\n", path, gap, data[path])
+	}
+}