V2 API Version Support

* Update blang/semver to allow ParseTolerant() support
* Provide helper functions for API handlers to obtain client's 'version'
  path variable focused on API endpoint tree: libpod vs. compat
* Introduce new errors:
  * version not given in path, endpoints may determine if this is a hard
    error (ErrVersionNotGiven)
  * given version not supported (ErrVersionNotSupported), only a soft
    error if the handler is going to hijack the connection
* Added unit tests for version parsing
* bindings check version on connect:
  * client <= Server API version connection is continued
  * client >= Server API version connection fails

Signed-off-by: Jhon Honce <jhonce@redhat.com>

2 files changed, 25 insertions, 25 deletions

diff --git a/pkg/api/handlers/compat/ping.go b/pkg/api/handlers/compat/ping.go
index 6e77e270f..abee3d8e8 100644
--- a/pkg/api/handlers/compat/ping.go
+++ b/pkg/api/handlers/compat/ping.go
@@ -5,22 +5,22 @@ import (
 	"net/http"
 
 	"github.com/containers/buildah"
-	"github.com/containers/libpod/pkg/api/handlers"
+	"github.com/containers/libpod/pkg/api/handlers/utils"
 )
 
 // Ping returns headers to client about the service
 //
 // This handler must always be the same for the compatibility and libpod URL trees!
 // Clients will use the Header availability to test which backend engine is in use.
+// Note: Additionally handler supports GET and HEAD methods
 func Ping(w http.ResponseWriter, r *http.Request) {
-	w.Header().Set("API-Version", handlers.DefaultApiVersion)
+	w.Header().Set("API-Version", utils.ApiVersion[utils.CompatTree][utils.CurrentApiVersion].String())
 	w.Header().Set("BuildKit-Version", "")
 	w.Header().Set("Docker-Experimental", "true")
 	w.Header().Set("Cache-Control", "no-cache")
 	w.Header().Set("Pragma", "no-cache")
 
-	// API-Version and Libpod-API-Version may not always be equal
-	w.Header().Set("Libpod-API-Version", handlers.DefaultApiVersion)
+	w.Header().Set("Libpod-API-Version", utils.ApiVersion[utils.LibpodTree][utils.CurrentApiVersion].String())
 	w.Header().Set("Libpod-Buildha-Version", buildah.Version)
 	w.WriteHeader(http.StatusOK)
 
diff --git a/pkg/api/handlers/compat/version.go b/pkg/api/handlers/compat/version.go
index 8786f1d5b..bfc226bb8 100644
--- a/pkg/api/handlers/compat/version.go
+++ b/pkg/api/handlers/compat/version.go
@@ -8,7 +8,6 @@ import (
 
 	"github.com/containers/libpod/libpod"
 	"github.com/containers/libpod/libpod/define"
-	"github.com/containers/libpod/pkg/api/handlers"
 	"github.com/containers/libpod/pkg/api/handlers/utils"
 	"github.com/containers/libpod/pkg/domain/entities"
 	docker "github.com/docker/docker/api/types"
@@ -35,34 +34,35 @@ func VersionHandler(w http.ResponseWriter, r *http.Request) {
 		Name:    "Podman Engine",
 		Version: versionInfo.Version,
 		Details: map[string]string{
-			"APIVersion":    handlers.DefaultApiVersion,
+			"APIVersion":    utils.ApiVersion[utils.LibpodTree][utils.CurrentApiVersion].String(),
 			"Arch":          goRuntime.GOARCH,
 			"BuildTime":     time.Unix(versionInfo.Built, 0).Format(time.RFC3339),
 			"Experimental":  "true",
 			"GitCommit":     versionInfo.GitCommit,
 			"GoVersion":     versionInfo.GoVersion,
 			"KernelVersion": infoData.Host.Kernel,
-			"MinAPIVersion": handlers.MinimalApiVersion,
+			"MinAPIVersion": utils.ApiVersion[utils.LibpodTree][utils.MinimalApiVersion].String(),
 			"Os":            goRuntime.GOOS,
 		},
 	}}
 
-	utils.WriteResponse(w, http.StatusOK, entities.ComponentVersion{Version: docker.Version{
-		Platform: struct {
-			Name string
-		}{
-			Name: fmt.Sprintf("%s/%s/%s-%s", goRuntime.GOOS, goRuntime.GOARCH, infoData.Host.Distribution.Distribution, infoData.Host.Distribution.Version),
-		},
-		APIVersion:    components[0].Details["APIVersion"],
-		Arch:          components[0].Details["Arch"],
-		BuildTime:     components[0].Details["BuildTime"],
-		Components:    components,
-		Experimental:  true,
-		GitCommit:     components[0].Details["GitCommit"],
-		GoVersion:     components[0].Details["GoVersion"],
-		KernelVersion: components[0].Details["KernelVersion"],
-		MinAPIVersion: components[0].Details["MinAPIVersion"],
-		Os:            components[0].Details["Os"],
-		Version:       components[0].Version,
-	}})
+	utils.WriteResponse(w, http.StatusOK, entities.ComponentVersion{
+		Version: docker.Version{
+			Platform: struct {
+				Name string
+			}{
+				Name: fmt.Sprintf("%s/%s/%s-%s", goRuntime.GOOS, goRuntime.GOARCH, infoData.Host.Distribution.Distribution, infoData.Host.Distribution.Version),
+			},
+			APIVersion:    components[0].Details["APIVersion"],
+			Arch:          components[0].Details["Arch"],
+			BuildTime:     components[0].Details["BuildTime"],
+			Components:    components,
+			Experimental:  true,
+			GitCommit:     components[0].Details["GitCommit"],
+			GoVersion:     components[0].Details["GoVersion"],
+			KernelVersion: components[0].Details["KernelVersion"],
+			MinAPIVersion: components[0].Details["MinAPIVersion"],
+			Os:            components[0].Details["Os"],
+			Version:       components[0].Version,
+		}})
 }