Add producer API to write specs

Signed-off-by: Evan Lezar <[email protected]>

pkg/cdi/producer/api.go

@@ -0,0 +1,29 @@
+/*
+   Copyright © 2024 The CDI Authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package producer
+
+type specFormat string
+
+const (
+	// DefaultSpecFormat defines the default encoding used to write CDI specs.
+	DefaultSpecFormat = SpecFormatYAML
+
+	// SpecFormatJSON defines a CDI spec formatted as JSON.
+	SpecFormatJSON = specFormat(".json")
+	// SpecFormatYAML defines a CDI spec formatted as YAML.
+	SpecFormatYAML = specFormat(".yaml")
+)

pkg/cdi/producer/options.go

@@ -0,0 +1,44 @@
+/*
+   Copyright © 2024 The CDI Authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package producer
+
+import "fmt"
+
+// An Option defines a functional option for constructing a producer.
+type Option func(*Producer) error
+
+// WithSpecFormat sets the output format of a CDI specification.
+func WithSpecFormat(format specFormat) Option {
+	return func(p *Producer) error {
+		switch format {
+		case SpecFormatJSON, SpecFormatYAML:
+			p.format = format
+		default:
+			return fmt.Errorf("invalid CDI spec format %v", format)
+		}
+		return nil
+	}
+}
+
+// WithOverwrite specifies whether a producer should overwrite a CDI spec when
+// saving to file.
+func WithOverwrite(overwrite bool) Option {
+	return func(p *Producer) error {
+		p.failIfExists = !overwrite
+		return nil
+	}
+}

pkg/cdi/producer/producer.go

@@ -0,0 +1,86 @@
+/*
+   Copyright © 2024 The CDI Authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package producer
+
+import (
+	"path/filepath"
+
+	cdi "tags.cncf.io/container-device-interface/specs-go"
+)
+
+// A Producer defines a structure for outputting CDI specifications.
+type Producer struct {
+	format       specFormat
+	failIfExists bool
+}
+
+// New creates a new producer with the supplied options.
+func New(opts ...Option) (*Producer, error) {
+	p := &Producer{
+		format: DefaultSpecFormat,
+	}
+	for _, opt := range opts {
+		err := opt(p)
+		if err != nil {
+			return nil, err
+		}
+	}
+	return p, nil
+}
+
+// SaveSpec writes the specified CDI spec to a file with the specified name.
+// If the filename ends in a supported extension, the format implied by the
+// extension takes precedence over the format with which the Producer was
+// configured.
+func (p *Producer) SaveSpec(s *cdi.Spec, filename string) (string, error) {
+	filename = p.normalizeFilename(filename)
+
+	sp := spec{
+		Spec:   s,
+		format: p.specFormatFromFilename(filename),
+	}
+
+	if err := sp.save(filename, !p.failIfExists); err != nil {
+		return "", err
+	}
+
+	return filename, nil
+}
+
+// specFormatFromFilename determines the CDI spec format for the given filename.
+func (p *Producer) specFormatFromFilename(filename string) specFormat {
+	switch filepath.Ext(filename) {
+	case ".json":
+		return SpecFormatJSON
+	case ".yaml", ".yml":
+		return SpecFormatYAML
+	default:
+		return p.format
+	}
+}
+
+// normalizeFilename ensures that the specified filename ends in a supported extension.
+func (p *Producer) normalizeFilename(filename string) string {
+	switch filepath.Ext(filename) {
+	case ".json":
+		fallthrough
+	case ".yaml", ".yml":
+		return filename
+	default:
+		return filename + string(p.format)
+	}
+}

pkg/cdi/producer/spec.go

@@ -0,0 +1,82 @@
+/*
+   Copyright © 2024 The CDI Authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package producer
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+	"path/filepath"
+
+	"sigs.k8s.io/yaml"
+
+	cdi "tags.cncf.io/container-device-interface/specs-go"
+)
+
+type spec struct {
+	*cdi.Spec
+	format specFormat
+}
+
+// save saves a CDI spec to the specified filename.
+func (s *spec) save(filename string, overwrite bool) error {
+	data, err := s.contents()
+	if err != nil {
+		return fmt.Errorf("failed to marshal Spec file: %w", err)
+	}
+
+	dir := filepath.Dir(filename)
+	if dir != "" {
+		if err := os.MkdirAll(dir, 0o755); err != nil {
+			return fmt.Errorf("failed to create Spec dir: %w", err)
+		}
+	}
+
+	tmp, err := os.CreateTemp(dir, "spec.*.tmp")
+	if err != nil {
+		return fmt.Errorf("failed to create Spec file: %w", err)
+	}
+	_, err = tmp.Write(data)
+	tmp.Close()
+	if err != nil {
+		return fmt.Errorf("failed to write Spec file: %w", err)
+	}
+
+	err = renameIn(dir, filepath.Base(tmp.Name()), filepath.Base(filename), overwrite)
+	if err != nil {
+		_ = os.Remove(tmp.Name())
+		return fmt.Errorf("failed to write Spec file: %w", err)
+	}
+	return nil
+}
+
+// contents returns the raw contents of a CDI specification.
+func (s *spec) contents() ([]byte, error) {
+	switch s.format {
+	case SpecFormatYAML:
+		data, err := yaml.Marshal(s.Spec)
+		if err != nil {
+			return nil, err
+		}
+		data = append([]byte("---\n"), data...)
+		return data, nil
+	case SpecFormatJSON:
+		return json.Marshal(s.Spec)
+	default:
+		return nil, fmt.Errorf("undefined CDI spec format %v", s.format)
+	}
+}

pkg/cdi/spec_linux.go → pkg/cdi/producer/spec_linux.go

@@ -14,7 +14,7 @@
    limitations under the License.
 */
 
-package cdi
+package producer
 
 import (
 	"fmt"

pkg/cdi/spec_other.go → pkg/cdi/producer/spec_other.go

@@ -17,7 +17,7 @@
    limitations under the License.
 */
 
-package cdi
+package producer
 
 import (
 	"os"

pkg/cdi/spec.go

@@ -17,7 +17,6 @@
 package cdi
 
 import (
-	"encoding/json"
 	"fmt"
 	"os"
 	"path/filepath"
@@ -28,6 +27,7 @@ import (
 	"sigs.k8s.io/yaml"
 
 	"tags.cncf.io/container-device-interface/internal/validation"
+	"tags.cncf.io/container-device-interface/pkg/cdi/producer"
 	"tags.cncf.io/container-device-interface/pkg/parser"
 	cdi "tags.cncf.io/container-device-interface/specs-go"
 )
@@ -118,52 +118,19 @@ func newSpec(raw *cdi.Spec, path string, priority int) (*Spec, error) {
 // Write the CDI Spec to the file associated with it during instantiation
 // by newSpec() or ReadSpec().
 func (s *Spec) write(overwrite bool) error {
-	var (
-		data []byte
-		dir  string
-		tmp  *os.File
-		err  error
+	p, err := producer.New(
+		producer.WithOverwrite(overwrite),
 	)
-
-	err = validateSpec(s.Spec)
 	if err != nil {
 		return err
 	}
 
-	if filepath.Ext(s.path) == ".yaml" {
-		data, err = yaml.Marshal(s.Spec)
-		data = append([]byte("---\n"), data...)
-	} else {
-		data, err = json.Marshal(s.Spec)
-	}
-	if err != nil {
-		return fmt.Errorf("failed to marshal Spec file: %w", err)
-	}
-
-	dir = filepath.Dir(s.path)
-	err = os.MkdirAll(dir, 0o755)
+	savedPath, err := p.SaveSpec(s.Spec, s.path)
 	if err != nil {
-		return fmt.Errorf("failed to create Spec dir: %w", err)
-	}
-
-	tmp, err = os.CreateTemp(dir, "spec.*.tmp")
-	if err != nil {
-		return fmt.Errorf("failed to create Spec file: %w", err)
-	}
-	_, err = tmp.Write(data)
-	tmp.Close()
-	if err != nil {
-		return fmt.Errorf("failed to write Spec file: %w", err)
-	}
-
-	err = renameIn(dir, filepath.Base(tmp.Name()), filepath.Base(s.path), overwrite)
-
-	if err != nil {
-		os.Remove(tmp.Name())
-		err = fmt.Errorf("failed to write Spec file: %w", err)
+		return err
 	}
-
-	return err
+	s.path = savedPath
+	return nil
 }
 
 // GetVendor returns the vendor of this Spec.