Add API examples (#2517)

* [wip] initial syft api examples

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

* smooth over some rough edges in the API

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

* embed example file

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

* address review comments

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

* change name of builder function

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

---------

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

examples/create_simple_sbom/main.go

@@ -0,0 +1,74 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"os"
+
+	"github.com/anchore/syft/syft"
+	"github.com/anchore/syft/syft/format"
+	"github.com/anchore/syft/syft/format/syftjson"
+	"github.com/anchore/syft/syft/sbom"
+	"github.com/anchore/syft/syft/source"
+)
+
+const defaultImage = "alpine:3.19"
+
+func main() {
+	// automagically get a source.Source for arbitrary string input
+	src := getSource(imageReference())
+
+	// catalog the given source and return a SBOM
+	sbom := getSBOM(src)
+
+	// take the SBOM object and encode it into the syft-json representation
+	bytes := formatSBOM(sbom)
+
+	// show the SBOM!
+	fmt.Println(string(bytes))
+}
+
+func imageReference() string {
+	// read an image string reference from the command line or use a default
+	if len(os.Args) > 1 {
+		return os.Args[1]
+	}
+	return defaultImage
+}
+
+func getSource(input string) source.Source {
+	detection, err := source.Detect(input,
+		source.DetectConfig{
+			DefaultImageSource: "docker",
+		},
+	)
+
+	if err != nil {
+		panic(err)
+	}
+
+	src, err := detection.NewSource(source.DefaultDetectionSourceConfig())
+
+	if err != nil {
+		panic(err)
+	}
+
+	return src
+}
+
+func getSBOM(src source.Source) sbom.SBOM {
+	s, err := syft.CreateSBOM(context.Background(), src, nil)
+	if err != nil {
+		panic(err)
+	}
+
+	return *s
+}
+
+func formatSBOM(s sbom.SBOM) []byte {
+	bytes, err := format.Encode(s, syftjson.NewFormatEncoder())
+	if err != nil {
+		panic(err)
+	}
+	return bytes
+}