versioning: misc cleanups

highlights:
 - NetConf struct finally includes cniVersion field
 - improve test coverage of current version report behavior
 - godoc a few key functions
 - allow tests to control version list reported by no-op plugin

invoke/exec.go

@@ -36,7 +36,7 @@ func GetVersionInfo(pluginPath string) (version.PluginInfo, error) {
 
 var defaultPluginExec = &PluginExec{
 	RawExec:        &RawExec{Stderr: os.Stderr},
-	VersionDecoder: &version.Decoder{},
+	VersionDecoder: &version.PluginDecoder{},
 }
 
 type PluginExec struct {
@@ -64,6 +64,10 @@ func (e *PluginExec) WithoutResult(pluginPath string, netconf []byte, args CNIAr
 	return err
 }
 
+// GetVersionInfo returns the version information available about the plugin.
+// For recent-enough plugins, it uses the information returned by the VERSION
+// command.  For older plugins which do not recognize that command, it reports
+// version 0.1.0
 func (e *PluginExec) GetVersionInfo(pluginPath string) (version.PluginInfo, error) {
 	args := &Args{
 		Command: "VERSION",

invoke/get_version_integration_test.go

@@ -54,9 +54,26 @@ var _ = Describe("GetVersion, integration tests", func() {
 		},
 		Entry("old plugin, before VERSION was introduced", git_ref_v010, plugin_source_v010, version.PluginSupports("0.1.0")),
 		Entry("when VERSION was introduced", git_ref_v020, plugin_source_v010, version.PluginSupports("0.1.0", "0.2.0")),
+		Entry("when plugins report their own version support", git_ref_v030, plugin_source_v030, version.PluginSupports("0.3.0", "0.999.0")),
+		Entry("HEAD", "HEAD", plugin_source_v030, version.PluginSupports("0.3.0", "0.999.0")),
 	)
 })
 
+// a 0.3.0 plugin that can report its own versions
+const plugin_source_v030 = `package main
+
+import (
+	"github.com/containernetworking/cni/pkg/skel"
+	"github.com/containernetworking/cni/pkg/version"
+	"fmt"
+)
+
+func c(_ *skel.CmdArgs) error { fmt.Println("{}"); return nil }
+
+func main() { skel.PluginMain(c, c, version.PluginSupports("0.3.0", "0.999.0")) }
+`
+const git_ref_v030 = "bf31ed15"
+
 // a minimal 0.1.0 / 0.2.0 plugin
 const plugin_source_v010 = `package main
 

types/types.go

@@ -57,6 +57,8 @@ func (n *IPNet) UnmarshalJSON(data []byte) error {
 
 // NetConf describes a network.
 type NetConf struct {
+	CNIVersion string `json:"cniVersion,omitempty"`
+
 	Name string `json:"name,omitempty"`
 	Type string `json:"type,omitempty"`
 	IPAM struct {

version/plugin.go

@@ -0,0 +1,77 @@
+// Copyright 2016 CNI 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 version
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+)
+
+// PluginInfo reports information about CNI versioning
+type PluginInfo interface {
+	// SupportedVersions returns one or more CNI spec versions that the plugin
+	// supports.  If input is provided in one of these versions, then the plugin
+	// promises to use the same CNI version in its response
+	SupportedVersions() []string
+
+	// Encode writes this CNI version information as JSON to the given Writer
+	Encode(io.Writer) error
+}
+
+type pluginInfo struct {
+	CNIVersion_        string   `json:"cniVersion"`
+	SupportedVersions_ []string `json:"supportedVersions,omitempty"`
+}
+
+func (p *pluginInfo) Encode(w io.Writer) error {
+	return json.NewEncoder(w).Encode(p)
+}
+
+func (p *pluginInfo) SupportedVersions() []string {
+	return p.SupportedVersions_
+}
+
+// PluginSupports returns a new PluginInfo that will report the given versions
+// as supported
+func PluginSupports(supportedVersions ...string) PluginInfo {
+	if len(supportedVersions) < 1 {
+		panic("programmer error: you must support at least one version")
+	}
+	return &pluginInfo{
+		CNIVersion_:        Current(),
+		SupportedVersions_: supportedVersions,
+	}
+}
+
+type PluginDecoder struct{}
+
+func (_ *PluginDecoder) Decode(jsonBytes []byte) (PluginInfo, error) {
+	var info pluginInfo
+	err := json.Unmarshal(jsonBytes, &info)
+	if err != nil {
+		return nil, fmt.Errorf("decoding version info: %s", err)
+	}
+	if info.CNIVersion_ == "" {
+		return nil, fmt.Errorf("decoding version info: missing field cniVersion")
+	}
+	if len(info.SupportedVersions_) == 0 {
+		if info.CNIVersion_ == "0.2.0" {
+			return PluginSupports("0.1.0", "0.2.0"), nil
+		}
+		return nil, fmt.Errorf("decoding version info: missing field supportedVersions")
+	}
+	return &info, nil
+}

version/plugin_test.go

@@ -20,11 +20,11 @@ import (
 	. "github.com/onsi/gomega"
 )
 
-var _ = Describe("Decode", func() {
-	var decoder *version.Decoder
+var _ = Describe("Decoding versions reported by a plugin", func() {
+	var decoder *version.PluginDecoder
 
 	BeforeEach(func() {
-		decoder = &version.Decoder{}
+		decoder = &version.PluginDecoder{}
 	})
 
 	It("returns a PluginInfo that represents the given json bytes", func() {

version/version.go

@@ -14,73 +14,11 @@
 
 package version
 
-import (
-	"encoding/json"
-	"fmt"
-	"io"
-)
-
 // Current reports the version of the CNI spec implemented by this library
 func Current() string {
 	return "0.3.0"
 }
 
-// PluginInfo reports information about CNI versioning
-type PluginInfo interface {
-	// SupportedVersions returns one or more CNI spec versions that the plugin
-	// supports.  If input is provided in one of these versions, then the plugin
-	// promises to use the same CNI version in its response
-	SupportedVersions() []string
-
-	// Encode writes this CNI version information as JSON to the given Writer
-	Encode(io.Writer) error
-}
-
-type simple struct {
-	CNIVersion_        string   `json:"cniVersion"`
-	SupportedVersions_ []string `json:"supportedVersions,omitempty"`
-}
-
-func (p *simple) Encode(w io.Writer) error {
-	return json.NewEncoder(w).Encode(p)
-}
-
-func (p *simple) SupportedVersions() []string {
-	return p.SupportedVersions_
-}
-
-// PluginSupports returns a new PluginInfo that will report the given versions
-// as supported
-func PluginSupports(supportedVersions ...string) PluginInfo {
-	if len(supportedVersions) < 1 {
-		panic("programmer error: you must support at least one version")
-	}
-	return &simple{
-		CNIVersion_:        Current(),
-		SupportedVersions_: supportedVersions,
-	}
-}
-
-type Decoder struct{}
-
-func (_ *Decoder) Decode(jsonBytes []byte) (PluginInfo, error) {
-	var info simple
-	err := json.Unmarshal(jsonBytes, &info)
-	if err != nil {
-		return nil, fmt.Errorf("decoding version info: %s", err)
-	}
-	if info.CNIVersion_ == "" {
-		return nil, fmt.Errorf("decoding version info: missing field cniVersion")
-	}
-	if len(info.SupportedVersions_) == 0 {
-		if info.CNIVersion_ == "0.2.0" {
-			return PluginSupports("0.1.0", "0.2.0"), nil
-		}
-		return nil, fmt.Errorf("decoding version info: missing field supportedVersions")
-	}
-	return &info, nil
-}
-
 // Legacy PluginInfo describes a plugin that is backwards compatible with the
 // CNI spec version 0.1.0.  In particular, a runtime compiled against the 0.1.0
 // library ought to work correctly with a plugin that reports support for