build: basis of build command

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>

build/secrets.go

@@ -0,0 +1,60 @@
+package build
+
+import (
+	"encoding/csv"
+	"strings"
+
+	"github.com/moby/buildkit/session"
+	"github.com/moby/buildkit/session/secrets/secretsprovider"
+	"github.com/pkg/errors"
+)
+
+func ParseSecretSpecs(sl []string) (session.Attachable, error) {
+	fs := make([]secretsprovider.FileSource, 0, len(sl))
+	for _, v := range sl {
+		s, err := parseSecret(v)
+		if err != nil {
+			return nil, err
+		}
+		fs = append(fs, *s)
+	}
+	store, err := secretsprovider.NewFileStore(fs)
+	if err != nil {
+		return nil, err
+	}
+	return secretsprovider.NewSecretProvider(store), nil
+}
+
+func parseSecret(value string) (*secretsprovider.FileSource, error) {
+	csvReader := csv.NewReader(strings.NewReader(value))
+	fields, err := csvReader.Read()
+	if err != nil {
+		return nil, errors.Wrap(err, "failed to parse csv secret")
+	}
+
+	fs := secretsprovider.FileSource{}
+
+	for _, field := range fields {
+		parts := strings.SplitN(field, "=", 2)
+		key := strings.ToLower(parts[0])
+
+		if len(parts) != 2 {
+			return nil, errors.Errorf("invalid field '%s' must be a key=value pair", field)
+		}
+
+		value := parts[1]
+		switch key {
+		case "type":
+			if value != "file" {
+				return nil, errors.Errorf("unsupported secret type %q", value)
+			}
+		case "id":
+			fs.ID = value
+		case "source", "src":
+			fs.FilePath = value
+		default:
+			return nil, errors.Errorf("unexpected key '%s' in '%s'", key, field)
+		}
+	}
+	return &fs, nil
+}