main: propagate the current Docker CLI context to $DOCKER_HOST

So that google/go-containerregistry can pick it up

Signed-off-by: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>

cmd/minikube/main.go

@@ -20,6 +20,7 @@ import (
 	"bytes"
 	"crypto/sha1"
 	"encoding/hex"
+	"errors"
 	"flag"
 	"fmt"
 	"log"
@@ -51,6 +52,10 @@ import (
 	"k8s.io/minikube/pkg/minikube/machine"
 	"k8s.io/minikube/pkg/minikube/out"
 	_ "k8s.io/minikube/pkg/provision"
+
+	dconfig "github.com/docker/cli/cli/config"
+	ddocker "github.com/docker/cli/cli/context/docker"
+	dstore "github.com/docker/cli/cli/context/store"
 )
 
 const minikubeEnableProfile = "MINIKUBE_ENABLE_PROFILING"
@@ -68,6 +73,8 @@ func main() {
 	bridgeLogMessages()
 	defer klog.Flush()
 
+	propagateDockerContextToEnv()
+
 	// Don't parse flags when running as kubectl
 	_, callingCmd := filepath.Split(os.Args[0])
 	callingCmd = strings.TrimSuffix(callingCmd, ".exe")
@@ -247,3 +254,54 @@ func setLastStartFlags() {
 		klog.Warningf("Unable to set default flag value for log_file: %v", err)
 	}
 }
+
+// propagateDockerContextToEnv propagates the current context in ~/.docker/config.json to $DOCKER_HOST,
+// so that google/go-containerregistry can pick it up.
+func propagateDockerContextToEnv() {
+	if os.Getenv("DOCKER_HOST") != "" {
+		// Already explicitly set
+		return
+	}
+	currentContext := os.Getenv("DOCKER_CONTEXT")
+	if currentContext == "" {
+		dockerConfigDir := dconfig.Dir()
+		if _, err := os.Stat(dockerConfigDir); err != nil {
+			if !errors.Is(err, os.ErrNotExist) {
+				klog.Warning(err)
+			}
+			return
+		}
+		cf, err := dconfig.Load(dockerConfigDir)
+		if err != nil {
+			klog.Warningf("Unable to load the current Docker config from %q", dockerConfigDir)
+			return
+		}
+		currentContext = cf.CurrentContext
+	}
+	if currentContext == "" {
+		return
+	}
+	storeConfig := dstore.NewConfig(
+		func() interface{} { return &ddocker.EndpointMeta{} },
+		dstore.EndpointTypeGetter(ddocker.DockerEndpoint, func() interface{} { return &ddocker.EndpointMeta{} }),
+	)
+	st := dstore.New(dconfig.ContextStoreDir(), storeConfig)
+	md, err := st.GetMetadata(currentContext)
+	if err != nil {
+		klog.Warningf("Unable to resolve the current Docker CLI context %q: %v", currentContext, err)
+		return
+	}
+	dockerEP, ok := md.Endpoints[ddocker.DockerEndpoint]
+	if !ok {
+		// No warning (the context is not for Docker)
+		return
+	}
+	dockerEPMeta, ok := dockerEP.(ddocker.EndpointMeta)
+	if !ok {
+		klog.Warningf("expected docker.EndpointMeta, got %T", dockerEP)
+		return
+	}
+	if dockerEPMeta.Host != "" {
+		os.Setenv("DOCKER_HOST", dockerEPMeta.Host)
+	}
+}

go.mod

@@ -96,6 +96,7 @@ require (
 require (
 	github.com/Xuanwo/go-locale v1.1.0
 	github.com/blang/semver v3.5.1+incompatible
+	github.com/docker/cli v20.10.20+incompatible
 	github.com/docker/go-connections v0.4.0
 	github.com/google/go-github/v43 v43.0.0
 	github.com/opencontainers/runc v1.1.4
@@ -128,13 +129,13 @@ require (
 	github.com/cpuguy83/go-md2man/v2 v2.0.2 // indirect
 	github.com/cyphar/filepath-securejoin v0.2.3 // indirect
 	github.com/davecgh/go-spew v1.1.1 // indirect
-	github.com/docker/cli v20.10.20+incompatible // indirect
 	github.com/docker/distribution v2.8.1+incompatible // indirect
 	github.com/docker/docker-credential-helpers v0.7.0 // indirect
 	github.com/emicklei/go-restful/v3 v3.9.0 // indirect
 	github.com/evanphx/json-patch v4.12.0+incompatible // indirect
 	github.com/fatih/color v1.13.0 // indirect
 	github.com/fsnotify/fsnotify v1.6.0 // indirect
+	github.com/fvbommel/sortorder v1.0.1 // indirect
 	github.com/go-fonts/liberation v0.2.0 // indirect
 	github.com/go-latex/latex v0.0.0-20210823091927-c0d11ff05a81 // indirect
 	github.com/go-logr/logr v1.2.3 // indirect

go.sum

@@ -411,6 +411,8 @@ github.com/fsnotify/fsnotify v1.4.9/go.mod h1:znqG4EE+3YCdAaPaxE2ZRY/06pZUdp0tY4
 github.com/fsnotify/fsnotify v1.6.0 h1:n+5WquG0fcWoWp6xPWfHdbskMCQaFnG6PfBrh1Ky4HY=
 github.com/fsnotify/fsnotify v1.6.0/go.mod h1:sl3t1tCWJFWoRz9R8WJCbQihKKwmorjAbSClcnxKAGw=
 github.com/fullsailor/pkcs7 v0.0.0-20190404230743-d7302db945fa/go.mod h1:KnogPXtdwXqoenmZCw6S+25EAm2MkxbG0deNDu4cbSA=
+github.com/fvbommel/sortorder v1.0.1 h1:dSnXLt4mJYH25uDDGa3biZNQsozaUWDSWeKJ0qqFfzE=
+github.com/fvbommel/sortorder v1.0.1/go.mod h1:uk88iVf1ovNn1iLfgUVU2F9o5eO30ui720w+kxuqRs0=
 github.com/garyburd/redigo v0.0.0-20150301180006-535138d7bcd7/go.mod h1:NR3MbYisc3/PwhQ00EMzDiPmrwpPxAn5GI05/YaO1SY=
 github.com/ghodss/yaml v0.0.0-20150909031657-73d445a93680/go.mod h1:4dBDuWmgqj2HViK6kFavaiC9ZROes6MMH2rRYeMEF04=
 github.com/ghodss/yaml v1.0.0/go.mod h1:4dBDuWmgqj2HViK6kFavaiC9ZROes6MMH2rRYeMEF04=