registry/search: pass User-Agent through headers

Commit 3991faf4640a46412a8af000ede78fc5cba76d0a moved search into the registry
package, which also made the `dockerversion` package a dependency for registry,
which brings additional (indirect) dependencies, such as `pkg/parsers/kernel`,
and `golang.org/x/sys/windows/registry`.

Client code, such as used in docker/cli may depend on the `registry` package,
but should not depend on those additional dependencies.

This patch moves setting the userAgent to the API router, and instead of
passing it as a separate argument, includes it into the "headers".

As these headers now not only contain the `X-Meta-...` headers, the variables
were renamed accordingly.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

2 files changed, 11 insertions, 8 deletions

diff --git a/api/server/router/image/backend.go b/api/server/router/image/backend.go
index 6dcee6f100..302b48d68e 100644
--- a/api/server/router/image/backend.go
+++ b/api/server/router/image/backend.go
@@ -42,5 +42,5 @@ type registryBackend interface {
 }
 
 type Searcher interface {
-	Search(ctx context.Context, searchFilters filters.Args, term string, limit int, authConfig *registry.AuthConfig, metaHeaders map[string][]string) ([]registry.SearchResult, error)
+	Search(ctx context.Context, searchFilters filters.Args, term string, limit int, authConfig *registry.AuthConfig, headers map[string][]string) ([]registry.SearchResult, error)
 }
diff --git a/api/server/router/image/image_routes.go b/api/server/router/image/image_routes.go
index 3140a663ab..d891b8158e 100644
--- a/api/server/router/image/image_routes.go
+++ b/api/server/router/image/image_routes.go
@@ -18,6 +18,7 @@ import (
 	"github.com/docker/docker/api/types/registry"
 	"github.com/docker/docker/api/types/versions"
 	"github.com/docker/docker/builder/remotecontext"
+	"github.com/docker/docker/dockerversion"
 	"github.com/docker/docker/errdefs"
 	"github.com/docker/docker/image"
 	"github.com/docker/docker/pkg/ioutils"
@@ -392,13 +393,6 @@ func (ir *imageRouter) getImagesSearch(ctx context.Context, w http.ResponseWrite
 		return err
 	}
 
-	var headers = map[string][]string{}
-	for k, v := range r.Header {
-		if strings.HasPrefix(k, "X-Meta-") {
-			headers[k] = v
-		}
-	}
-
 	var limit int
 	if r.Form.Get("limit") != "" {
 		var err error
@@ -415,6 +409,15 @@ func (ir *imageRouter) getImagesSearch(ctx context.Context, w http.ResponseWrite
 	// For a search it is not an error if no auth was given. Ignore invalid
 	// AuthConfig to increase compatibility with the existing API.
 	authConfig, _ := registry.DecodeAuthConfig(r.Header.Get(registry.AuthHeader))
+
+	var headers = http.Header{}
+	for k, v := range r.Header {
+		k = http.CanonicalHeaderKey(k)
+		if strings.HasPrefix(k, "X-Meta-") {
+			headers[k] = v
+		}
+	}
+	headers.Set("User-Agent", dockerversion.DockerUserAgent(ctx))
 	res, err := ir.searcher.Search(ctx, searchFilters, r.Form.Get("term"), limit, authConfig, headers)
 	if err != nil {
 		return err