Merge pull request #449 from Aishwarya-Lad/CI-13422

Change docker login method, from config writing to login func

.drone.yml

@@ -12,7 +12,7 @@ platform:
 
 steps:
   - name: vet
-    image: golang:1.22
+    image: golang:1.22.4
     commands:
       - go vet ./...
     environment:
@@ -22,7 +22,7 @@ steps:
         path: /go
 
   - name: test
-    image: golang:1.22
+    image: golang:1.22.4
     commands:
       - go test -cover ./...
     environment:
@@ -55,7 +55,7 @@ platform:
 
 steps:
   - name: go build
-    image: golang:1.22
+    image: golang:1.22.4
     environment:
       CGO_ENABLED: 0
     commands:
@@ -162,7 +162,7 @@ platform:
 
 steps:
   - name: go build
-    image: golang:1.22
+    image: golang:1.22.4
     environment:
       CGO_ENABLED: 0
     commands:
@@ -172,7 +172,7 @@ steps:
       - go build -o release/windows/amd64/drone-acr.exe ./cmd/drone-acr
       - go build -o release/windows/amd64/drone-gar.exe ./cmd/drone-gar
   - name: build docker plugin
-    image: plugins/docker
+    image: plugins/docker@sha256:f0233d950ae87ee6cb5500b2d5497fe02aa338201c0bdce2619f443fd174cfa4
     settings:
       dockerfile: docker/docker/Dockerfile.windows.amd64.ltsc2022
       repo: plugins/docker
@@ -186,7 +186,7 @@ steps:
     when:
       event: [push, tag]
   - name: build ecr plugin
-    image: plugins/docker
+    image: plugins/docker@sha256:f0233d950ae87ee6cb5500b2d5497fe02aa338201c0bdce2619f443fd174cfa4
     settings:
       dockerfile: docker/ecr/Dockerfile.windows.amd64.ltsc2022
       repo: plugins/ecr
@@ -200,7 +200,7 @@ steps:
     when:
       event: [push, tag]
   - name: build gcr plugin
-    image: plugins/docker
+    image: plugins/docker@sha256:f0233d950ae87ee6cb5500b2d5497fe02aa338201c0bdce2619f443fd174cfa4
     settings:
       dockerfile: docker/gcr/Dockerfile.windows.amd64.ltsc2022
       repo: plugins/gcr
@@ -214,7 +214,7 @@ steps:
     when:
       event: [push, tag]
   - name: build acr plugin
-    image: plugins/docker
+    image: plugins/docker@sha256:f0233d950ae87ee6cb5500b2d5497fe02aa338201c0bdce2619f443fd174cfa4
     settings:
       dockerfile: docker/acr/Dockerfile.windows.amd64.ltsc2022
       repo: plugins/acr
@@ -228,7 +228,7 @@ steps:
     when:
       event: [push, tag]
   - name: build gar plugin
-    image: plugins/docker
+    image: plugins/docker@sha256:f0233d950ae87ee6cb5500b2d5497fe02aa338201c0bdce2619f443fd174cfa4
     settings:
       dockerfile: docker/gar/Dockerfile.windows.amd64.ltsc2022
       repo: plugins/gar
@@ -264,7 +264,7 @@ platform:
 
 steps:
   - name: build-push
-    image: golang:1.22
+    image: golang:1.22.4
     commands:
       - 'go build -v -ldflags "-X main.version=${DRONE_COMMIT_SHA:0:8}" -a -tags netgo -o release/linux/amd64/drone-docker ./cmd/drone-docker'
     environment:
@@ -275,7 +275,7 @@ steps:
           - tag
 
   - name: build-tag
-    image: golang:1.22
+    image: golang:1.22.4
     commands:
       - 'go build -v -ldflags "-X main.version=${DRONE_TAG##v}" -a -tags netgo -o release/linux/amd64/drone-docker ./cmd/drone-docker'
     environment:
@@ -285,7 +285,7 @@ steps:
         - tag
 
   - name: executable
-    image: golang:1.22
+    image: golang:1.22.4
     commands:
       - ./release/linux/amd64/drone-docker --help
 
@@ -329,7 +329,7 @@ platform:
 
 steps:
   - name: build-push
-    image: golang:1.22
+    image: golang:1.22.4
     commands:
       - 'go build -v -ldflags "-X main.version=${DRONE_COMMIT_SHA:0:8}" -a -tags netgo -o release/linux/arm64/drone-docker ./cmd/drone-docker'
     environment:
@@ -340,7 +340,7 @@ steps:
           - tag
 
   - name: build-tag
-    image: golang:1.22
+    image: golang:1.22.4
     commands:
       - 'go build -v -ldflags "-X main.version=${DRONE_TAG##v}" -a -tags netgo -o release/linux/arm64/drone-docker ./cmd/drone-docker'
     environment:
@@ -350,7 +350,7 @@ steps:
         - tag
 
   - name: executable
-    image: golang:1.22
+    image: golang:1.22.4
     commands:
       - ./release/linux/arm64/drone-docker --help
 
@@ -429,7 +429,7 @@ platform:
 
 steps:
   - name: build-push
-    image: golang:1.22
+    image: golang:1.22.4
     commands:
       - 'go build -v -ldflags "-X main.version=${DRONE_COMMIT_SHA:0:8}" -a -tags netgo -o release/linux/amd64/drone-gcr ./cmd/drone-gcr'
     environment:
@@ -440,7 +440,7 @@ steps:
           - tag
 
   - name: build-tag
-    image: golang:1.22
+    image: golang:1.22.4
     commands:
       - 'go build -v -ldflags "-X main.version=${DRONE_TAG##v}" -a -tags netgo -o release/linux/amd64/drone-gcr ./cmd/drone-gcr'
     environment:
@@ -488,7 +488,7 @@ platform:
 
 steps:
   - name: build-push
-    image: golang:1.22
+    image: golang:1.22.4
     commands:
       - 'go build -v -ldflags "-X main.version=${DRONE_COMMIT_SHA:0:8}" -a -tags netgo -o release/linux/arm64/drone-gcr ./cmd/drone-gcr'
     environment:
@@ -499,7 +499,7 @@ steps:
           - tag
 
   - name: build-tag
-    image: golang:1.22
+    image: golang:1.22.4
     commands:
       - 'go build -v -ldflags "-X main.version=${DRONE_TAG##v}" -a -tags netgo -o release/linux/arm64/drone-gcr ./cmd/drone-gcr'
     environment:
@@ -582,7 +582,7 @@ platform:
 
 steps:
   - name: build-push
-    image: golang:1.22
+    image: golang:1.22.4
     commands:
       - 'go build -v -ldflags "-X main.version=${DRONE_COMMIT_SHA:0:8}" -a -tags netgo -o release/linux/amd64/drone-gar ./cmd/drone-gar'
     environment:
@@ -593,7 +593,7 @@ steps:
           - tag
 
   - name: build-tag
-    image: golang:1.22
+    image: golang:1.22.4
     commands:
       - 'go build -v -ldflags "-X main.version=${DRONE_TAG##v}" -a -tags netgo -o release/linux/amd64/drone-gar ./cmd/drone-gar'
     environment:
@@ -641,7 +641,7 @@ platform:
 
 steps:
   - name: build-push
-    image: golang:1.22
+    image: golang:1.22.4
     commands:
       - 'go build -v -ldflags "-X main.version=${DRONE_COMMIT_SHA:0:8}" -a -tags netgo -o release/linux/arm64/drone-gar ./cmd/drone-gar'
     environment:
@@ -652,7 +652,7 @@ steps:
           - tag
 
   - name: build-tag
-    image: golang:1.22
+    image: golang:1.22.4
     commands:
       - 'go build -v -ldflags "-X main.version=${DRONE_TAG##v}" -a -tags netgo -o release/linux/arm64/drone-gar ./cmd/drone-gar'
     environment:
@@ -734,7 +734,7 @@ platform:
 
 steps:
   - name: build-push
-    image: golang:1.22
+    image: golang:1.22.4
     commands:
       - 'go build -v -ldflags "-X main.version=${DRONE_COMMIT_SHA:0:8}" -a -tags netgo -o release/linux/amd64/drone-ecr ./cmd/drone-ecr'
     environment:
@@ -744,7 +744,7 @@ steps:
         exclude:
           - tag
   - name: build-tag
-    image: golang:1.22
+    image: golang:1.22.4
     commands:
       - 'go build -v -ldflags "-X main.version=${DRONE_TAG##v}" -a -tags netgo -o release/linux/amd64/drone-ecr ./cmd/drone-ecr'
     environment:
@@ -792,7 +792,7 @@ platform:
 
 steps:
   - name: build-push
-    image: golang:1.22
+    image: golang:1.22.4
     commands:
       - 'go build -v -ldflags "-X main.version=${DRONE_COMMIT_SHA:0:8}" -a -tags netgo -o release/linux/arm64/drone-ecr ./cmd/drone-ecr'
     environment:
@@ -802,7 +802,7 @@ steps:
         exclude:
           - tag
   - name: build-tag
-    image: golang:1.22
+    image: golang:1.22.4
     commands:
       - 'go build -v -ldflags "-X main.version=${DRONE_TAG##v}" -a -tags netgo -o release/linux/arm64/drone-ecr ./cmd/drone-ecr'
     environment:
@@ -885,7 +885,7 @@ platform:
 
 steps:
   - name: build-push
-    image: golang:1.22
+    image: golang:1.22.4
     commands:
       - 'go build -v -ldflags "-X main.version=${DRONE_COMMIT_SHA:0:8}" -a -tags netgo -o release/linux/amd64/drone-heroku ./cmd/drone-heroku'
     environment:
@@ -895,7 +895,7 @@ steps:
         exclude:
           - tag
   - name: build-tag
-    image: golang:1.22
+    image: golang:1.22.4
     commands:
       - 'go build -v -ldflags "-X main.version=${DRONE_TAG##v}" -a -tags netgo -o release/linux/amd64/drone-heroku ./cmd/drone-heroku'
     environment:
@@ -944,7 +944,7 @@ platform:
 
 steps:
   - name: build-push
-    image: golang:1.22
+    image: golang:1.22.4
     commands:
       - 'go build -v -ldflags "-X main.version=${DRONE_COMMIT_SHA:0:8}" -a -tags netgo -o release/linux/arm64/drone-heroku ./cmd/drone-heroku'
     environment:
@@ -954,7 +954,7 @@ steps:
         exclude:
           - tag
   - name: build-tag
-    image: golang:1.22
+    image: golang:1.22.4
     commands:
       - 'go build -v -ldflags "-X main.version=${DRONE_TAG##v}" -a -tags netgo -o release/linux/arm64/drone-heroku ./cmd/drone-heroku'
     environment:
@@ -1035,7 +1035,7 @@ platform:
 
 steps:
   - name: build-push
-    image: golang:1.22
+    image: golang:1.22.4
     commands:
       - 'go build -v -ldflags "-X main.build=${DRONE_BUILD_NUMBER}" -a -tags netgo -o release/linux/amd64/drone-acr ./cmd/drone-acr'
     environment:
@@ -1045,7 +1045,7 @@ steps:
         exclude:
           - tag
   - name: build-tag
-    image: golang:1.22
+    image: golang:1.22.4
     commands:
       - 'go build -v -ldflags "-X main.version=${DRONE_TAG##v} -X main.build=${DRONE_BUILD_NUMBER}" -a -tags netgo -o release/linux/amd64/drone-acr ./cmd/drone-acr'
     environment:
@@ -1093,7 +1093,7 @@ platform:
 
 steps:
   - name: build-push
-    image: golang:1.22
+    image: golang:1.22.4
     commands:
       - 'go build -v -ldflags "-X main.build=${DRONE_BUILD_NUMBER}" -a -tags netgo -o release/linux/arm64/drone-acr ./cmd/drone-acr'
     environment:
@@ -1104,7 +1104,7 @@ steps:
           - tag
 
   - name: build-tag
-    image: golang:1.22
+    image: golang:1.22.4
     commands:
       - 'go build -v -ldflags "-X main.version=${DRONE_TAG##v} -X main.build=${DRONE_BUILD_NUMBER}" -a -tags netgo -o release/linux/arm64/drone-acr ./cmd/drone-acr'
     environment:

cmd/drone-docker/main.go

@@ -222,6 +222,21 @@ func main() {
 			Usage:  "docker password",
 			EnvVar: "PLUGIN_PASSWORD,DOCKER_PASSWORD",
 		},
+		cli.StringFlag{
+			Name:   "docker.baseimageusername",
+			Usage:  "Docker username for base image registry",
+			EnvVar: "PLUGIN_DOCKER_USERNAME,PLUGIN_BASE_IMAGE_USERNAME,DOCKER_BASE_IMAGE_USERNAME",
+		},
+		cli.StringFlag{
+			Name:   "docker.baseimagepassword",
+			Usage:  "Docker password for base image registry",
+			EnvVar: "PLUGIN_DOCKER_PASSWORD,PLUGIN_BASE_IMAGE_PASSWORD,DOCKER_BASE_IMAGE_PASSWORD",
+		},
+		cli.StringFlag{
+			Name:   "docker.baseimageregistry",
+			Usage:  "Docker registry for base image registry",
+			EnvVar: "PLUGIN_DOCKER_REGISTRY,PLUGIN_BASE_IMAGE_REGISTRY,DOCKER_BASE_IMAGE_REGISTRY",
+		},
 		cli.StringFlag{
 			Name:   "docker.email",
 			Usage:  "docker email",
@@ -367,6 +382,9 @@ func run(c *cli.Context) error {
 			Experimental:  c.Bool("daemon.experimental"),
 			RegistryType:  registryType,
 		},
+		BaseImageRegistry: c.String("docker.baseimageregistry"),
+		BaseImageUsername: c.String("docker.baseimageusername"),
+		BaseImagePassword: c.String("docker.baseimagepassword"),
 	}
 
 	if c.Bool("tags.auto") {

cmd/drone-ecr/main.go

@@ -42,7 +42,7 @@ func main() {
 		assumeRole       = getenv("PLUGIN_ASSUME_ROLE")
 		externalId       = getenv("PLUGIN_EXTERNAL_ID")
 		scanOnPush       = parseBoolOrDefault(false, getenv("PLUGIN_SCAN_ON_PUSH"))
-		idToken          = os.Getenv("PLUGIN_OIDC_TOKEN_ID") 
+		idToken          = os.Getenv("PLUGIN_OIDC_TOKEN_ID")
 	)
 
 	// set the region
@@ -218,9 +218,24 @@ func getECRClient(sess *session.Session, role string, externalId string, idToken
 	if role == "" {
 		return ecr.New(sess)
 	}
-	// Use STS AssumeRoleWithWebIdentity when idToken is provided
+
 	if idToken != "" {
-		creds := stscreds.NewWebIdentityCredentials(sess, role, "", idToken)
+		tempFile, err := os.CreateTemp("/tmp", "idToken-*.jwt")
+		if err != nil {
+			log.Fatalf("Failed to create temporary file: %v", err)
+		}
+		defer tempFile.Close()
+
+		if err := os.Chmod(tempFile.Name(), 0600); err != nil {
+			log.Fatalf("Failed to set file permissions: %v", err)
+		}
+
+		if _, err := tempFile.WriteString(idToken); err != nil {
+			log.Fatalf("Failed to write ID token to temporary file: %v", err)
+		}
+
+		// Create credentials using the path to the ID token file
+		creds := stscreds.NewWebIdentityCredentials(sess, role, "", tempFile.Name())
 		return ecr.New(sess, &aws.Config{Credentials: creds})
 	} else if externalId != "" {
 		return ecr.New(sess, &aws.Config{

docker.go

@@ -10,6 +10,7 @@ import (
 	"strings"
 	"time"
 
+	"github.com/drone-plugins/drone-docker/internal/docker"
 	"github.com/drone-plugins/drone-plugin-lib/drone"
 )
 
@@ -75,13 +76,16 @@ type (
 
 	// Plugin defines the Docker plugin parameters.
 	Plugin struct {
-		Login        Login  // Docker login configuration
-		Build        Build  // Docker build configuration
-		Daemon       Daemon // Docker daemon configuration
-		Dryrun       bool   // Docker push is skipped
-		Cleanup      bool   // Docker purge is enabled
-		CardPath     string // Card path to write file to
-		ArtifactFile string // Artifact path to write file to
+		Login             Login  // Docker login configuration
+		Build             Build  // Docker build configuration
+		Daemon            Daemon // Docker daemon configuration
+		Dryrun            bool   // Docker push is skipped
+		Cleanup           bool   // Docker purge is enabled
+		CardPath          string // Card path to write file to
+		ArtifactFile      string // Artifact path to write file to
+		BaseImageRegistry string // Docker registry to pull base image
+		BaseImageUsername string // Docker registry username to pull base image
+		BaseImagePassword string // Docker registry password to pull base image
 	}
 
 	Card []struct {
@@ -160,6 +164,29 @@ func (p Plugin) Exec() error {
 		}
 	}
 
+	// instead of writing to config file directly, using docker's login func
+	// is better to integrate with various credential helpers,
+	//	it also handles different registry specific logic in a better way,
+	//	as opposed to config write where different registries need to be addressed differently.
+	//	It handles any changes in the authentication process across different Docker versions.
+
+	if p.BaseImagePassword != "" {
+		var baseConnectorLogin Login
+		baseConnectorLogin.Registry = p.BaseImageRegistry
+		baseConnectorLogin.Username = p.BaseImageUsername
+		baseConnectorLogin.Password = p.BaseImagePassword
+
+		cmd := commandLogin(baseConnectorLogin)
+
+		raw, err := cmd.CombinedOutput()
+		if err != nil {
+			out := string(raw)
+			out = strings.Replace(out, "WARNING! Using --password via the CLI is insecure. Use --password-stdin.", "", -1)
+			fmt.Println(out)
+			return fmt.Errorf("Error authenticating base connector: exit status 1")
+		}
+	}
+
 	// login to the Docker registry
 	if p.Login.Password != "" {
 		cmd := commandLogin(p.Login)
@@ -270,6 +297,35 @@ func (p Plugin) Exec() error {
 	return nil
 }
 
+// helper function to set the credentials
+func setDockerAuth(username, password, registry, baseImageUsername,
+	baseImagePassword, baseImageRegistry string) ([]byte, error) {
+	var credentials []docker.RegistryCredentials
+	// add only docker registry to the config
+	dockerConfig := docker.NewConfig()
+	if password != "" {
+		pushToRegistryCreds := docker.RegistryCredentials{
+			Registry: registry,
+			Username: username,
+			Password: password,
+		}
+		// push registry auth
+		credentials = append(credentials, pushToRegistryCreds)
+	}
+
+	if baseImageRegistry != "" {
+		pullFromRegistryCreds := docker.RegistryCredentials{
+			Registry: baseImageRegistry,
+			Username: baseImageUsername,
+			Password: baseImagePassword,
+		}
+		// base image registry auth
+		credentials = append(credentials, pullFromRegistryCreds)
+	}
+	// Creates docker config for both the registries used for authentication
+	return dockerConfig.CreateDockerConfigJson(credentials)
+}
+
 // helper function to create the docker login command.
 func commandLogin(login Login) *exec.Cmd {
 	if login.Email != "" {

go.mod

@@ -9,6 +9,7 @@ require (
 	github.com/inhies/go-bytesize v0.0.0-20210819104631-275770b98743
 	github.com/joho/godotenv v1.3.0
 	github.com/sirupsen/logrus v1.9.0
+	github.com/stretchr/testify v1.8.1
 	github.com/urfave/cli v1.22.2
 	golang.org/x/oauth2 v0.13.0
 )
@@ -17,6 +18,7 @@ require (
 	cloud.google.com/go/compute v1.23.1 // indirect
 	cloud.google.com/go/compute/metadata v0.2.3 // indirect
 	github.com/cpuguy83/go-md2man/v2 v2.0.2 // indirect
+	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/golang/groupcache v0.0.0-20210331224755-41bb18bfe9da // indirect
 	github.com/golang/protobuf v1.5.3 // indirect
 	github.com/google/s2a-go v0.1.7 // indirect
@@ -24,6 +26,7 @@ require (
 	github.com/googleapis/enterprise-certificate-proxy v0.3.1 // indirect
 	github.com/googleapis/gax-go/v2 v2.12.0 // indirect
 	github.com/jmespath/go-jmespath v0.0.0-20180206201540-c2b33e8439af // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/russross/blackfriday/v2 v2.1.0 // indirect
 	go.opencensus.io v0.24.0 // indirect
 	golang.org/x/crypto v0.14.0 // indirect
@@ -39,4 +42,4 @@ require (
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 )
 
-go 1.22
+go 1.22.4

go.sum

@@ -90,6 +90,7 @@ github.com/stretchr/testify v1.7.0 h1:nwc3DEeHmmLAfoZucVR881uASk0Mfjw8xYJ99tb5Cc
 github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 github.com/stretchr/testify v1.8.0/go.mod h1:yNjHg4UonilssWZ8iaSj1OCr/vHnekPRkoO+kdMU+MU=
+github.com/stretchr/testify v1.8.1 h1:w7B6lhMri9wdJUVmEZPGGhZzrYTPvgJArz7wNPgYKsk=
 github.com/stretchr/testify v1.8.1/go.mod h1:w2LPCIKwWwSfY2zedu0+kehJoqGctiVI29o6fzry7u4=
 github.com/urfave/cli v1.22.2 h1:gsqYFH8bb9ekPA12kRo0hfjngWQjkJPlN9R0N78BoUo=
 github.com/urfave/cli v1.22.2/go.mod h1:Gos4lmkARVdJ6EkW0WaNv/tZAAMe9V7XWyB60NtXRu0=

internal/docker/config.go

@@ -0,0 +1,70 @@
+package docker
+
+import (
+	"encoding/base64"
+	"encoding/json"
+	"errors"
+	"fmt"
+)
+
+const (
+	v2HubRegistryURL string = "https://registry.hub.docker.com/v2/"
+	v1RegistryURL    string = "https://index.docker.io/v1/" // Default registry
+	v2RegistryURL    string = "https://index.docker.io/v2/" // v2 registry is not supported
+)
+
+type (
+	Auth struct {
+		Auth string `json:"auth"`
+	}
+
+	Config struct {
+		Auths       map[string]Auth   `json:"auths"`
+		CredHelpers map[string]string `json:"credHelpers,omitempty"`
+	}
+)
+
+type RegistryCredentials struct {
+	Registry string
+	Username string
+	Password string
+}
+
+func NewConfig() *Config {
+	return &Config{
+		Auths:       make(map[string]Auth),
+		CredHelpers: make(map[string]string),
+	}
+}
+
+func (c *Config) SetAuth(registry, username, password string) {
+	authBytes := []byte(username + ":" + password)
+	encodedString := base64.StdEncoding.EncodeToString(authBytes)
+	c.Auths[registry] = Auth{Auth: encodedString}
+}
+
+func (c *Config) SetCredHelper(registry, helper string) {
+	c.CredHelpers[registry] = helper
+}
+
+func (c *Config) CreateDockerConfigJson(credentials []RegistryCredentials) ([]byte, error) {
+	for _, cred := range credentials {
+		if cred.Registry != "" {
+
+			if cred.Username == "" {
+				return nil, fmt.Errorf("Username must be specified for registry: %s", cred.Registry)
+			}
+			if cred.Password == "" {
+				return nil, fmt.Errorf("Password must be specified for registry: %s", cred.Registry)
+			}
+			c.SetAuth(cred.Registry, cred.Username, cred.Password)
+		}
+	}
+
+	jsonBytes, err := json.Marshal(c)
+	if err != nil {
+		return nil, errors.New("failed to serialize docker config json")
+	}
+
+	return jsonBytes, nil
+}

internal/docker/config_test.go

@@ -0,0 +1,64 @@
+package docker
+
+import (
+	"encoding/json"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+const (
+	RegistryV1        string = "https://index.docker.io/v1/"
+	RegistryV2        string = "https://index.docker.io/v2/"
+	RegistryECRPublic string = "public.ecr.aws"
+)
+
+func TestConfig(t *testing.T) {
+	c := NewConfig()
+	assert.NotNil(t, c.Auths)
+	assert.NotNil(t, c.CredHelpers)
+
+	c.SetAuth(RegistryV1, "test", "password")
+	expectedAuth := Auth{Auth: "dGVzdDpwYXNzd29yZA=="}
+	assert.Equal(t, expectedAuth, c.Auths[RegistryV1])
+
+	c.SetCredHelper(RegistryECRPublic, "ecr-login")
+	assert.Equal(t, "ecr-login", c.CredHelpers[RegistryECRPublic])
+
+	tempDir, err := ioutil.TempDir("", "docker-config-test")
+	assert.NoError(t, err)
+	defer os.RemoveAll(tempDir)
+
+	credentials := []RegistryCredentials{
+		{
+			Registry: "https://index.docker.io/v1/",
+			Username: "user1",
+			Password: "pass1",
+		},
+		{
+			Registry: "gcr.io",
+			Username: "user2",
+			Password: "pass2",
+		},
+	}
+
+	jsonBytes, err := c.CreateDockerConfigJson(credentials)
+	assert.NoError(t, err)
+
+	configPath := filepath.Join(tempDir, "config.json")
+	err = ioutil.WriteFile(configPath, jsonBytes, 0644)
+	assert.NoError(t, err)
+
+	data, err := ioutil.ReadFile(configPath)
+	assert.NoError(t, err)
+
+	var configFromFile Config
+	err = json.Unmarshal(data, &configFromFile)
+	assert.NoError(t, err)
+
+	assert.Equal(t, c.Auths, configFromFile.Auths)
+	assert.Equal(t, c.CredHelpers, configFromFile.CredHelpers)
+}