Add support for multiple Buildkit secrets with env vars or files as source (#359)

cmd/drone-docker/main.go

@@ -254,6 +254,16 @@ func main() {
 			Usage:  "secret key value pair eg id=MYSECRET",
 			EnvVar: "PLUGIN_SECRET",
 		},
+		cli.StringSliceFlag{
+			Name:   "secrets-from-env",
+			Usage:  "secret key value pair eg secret_name=secret",
+			EnvVar: "PLUGIN_SECRETS_FROM_ENV",
+		},
+		cli.StringSliceFlag{
+			Name:   "secrets-from-file",
+			Usage:  "secret key value pairs eg secret_name=/path/to/secret",
+			EnvVar: "PLUGIN_SECRETS_FROM_FILE",
+		},
 		cli.StringFlag{
 			Name:   "drone-card-path",
 			Usage:  "card path location to write to",
@@ -298,6 +308,8 @@ func run(c *cli.Context) error {
 			Link:        c.String("link"),
 			NoCache:     c.Bool("no-cache"),
 			Secret:      c.String("secret"),
+			SecretEnvs:  c.StringSlice("secrets-from-env"),
+			SecretFiles: c.StringSlice("secrets-from-file"),
 			AddHost:     c.StringSlice("add-host"),
 			Quiet:       c.Bool("quiet"),
 		},

docker.go

@@ -59,6 +59,8 @@ type (
 		Link        string   // Git repo link
 		NoCache     bool     // Docker build no-cache
 		Secret      string   // secret keypair
+		SecretEnvs  []string // Docker build secrets with env var as source
+		SecretFiles []string // Docker build secrets with file as source
 		AddHost     []string // Docker build add-host
 		Quiet       bool     // Docker build quiet
 	}
@@ -306,6 +308,16 @@ func commandBuild(build Build) *exec.Cmd {
 	if build.Secret != "" {
 		args = append(args, "--secret", build.Secret)
 	}
+	for _, secret := range build.SecretEnvs {
+		if arg, err := getSecretStringCmdArg(secret); err == nil {
+			args = append(args, "--secret", arg)
+		}
+	}
+	for _, secret := range build.SecretFiles {
+		if arg, err := getSecretFileCmdArg(secret); err == nil {
+			args = append(args, "--secret", arg)
+		}
+	}
 	if build.Target != "" {
 		args = append(args, "--target", build.Target)
 	}
@@ -338,12 +350,40 @@ func commandBuild(build Build) *exec.Cmd {
 	}
 
 	// we need to enable buildkit, for secret support
-	if build.Secret != "" {
+	if build.Secret != "" || len(build.SecretEnvs) > 0 || len(build.SecretFiles) > 0 {
 		os.Setenv("DOCKER_BUILDKIT", "1")
 	}
 	return exec.Command(dockerExe, args...)
 }
 
+func getSecretStringCmdArg(kvp string) (string, error) {
+	return getSecretCmdArg(kvp, false)
+}
+
+func getSecretFileCmdArg(kvp string) (string, error) {
+	return getSecretCmdArg(kvp, true)
+}
+
+func getSecretCmdArg(kvp string, file bool) (string, error) {
+	delimIndex := strings.IndexByte(kvp, '=')
+	if delimIndex == -1 {
+		return "", fmt.Errorf("%s is not a valid secret", kvp)
+	}
+
+	key := kvp[:delimIndex]
+	value := kvp[delimIndex+1:]
+
+	if key == "" || value == "" {
+		return "", fmt.Errorf("%s is not a valid secret", kvp)
+	}
+
+	if file {
+		return fmt.Sprintf("id=%s,src=%s", key, value), nil
+	}
+
+	return fmt.Sprintf("id=%s,env=%s", key, value), nil
+}
+
 // helper function to add proxy values from the environment
 func addProxyBuildArgs(build *Build) {
 	addProxyValue(build, "http_proxy")

docker_test.go

@@ -1 +1,130 @@
 package docker
+
+import (
+	"os/exec"
+	"reflect"
+	"testing"
+)
+
+func TestCommandBuild(t *testing.T) {
+	tcs := []struct {
+		name  string
+		build Build
+		want  *exec.Cmd
+	}{
+		{
+			name: "secret from env var",
+			build: Build{
+				Name:       "plugins/drone-docker:latest",
+				Dockerfile: "Dockerfile",
+				Context:    ".",
+				SecretEnvs: []string{
+					"foo_secret=FOO_SECRET_ENV_VAR",
+				},
+			},
+			want: exec.Command(
+				dockerExe,
+				"build",
+				"--rm=true",
+				"-f",
+				"Dockerfile",
+				"-t",
+				"plugins/drone-docker:latest",
+				".",
+				"--secret id=foo_secret,env=FOO_SECRET_ENV_VAR",
+			),
+		},
+		{
+			name: "secret from file",
+			build: Build{
+				Name:       "plugins/drone-docker:latest",
+				Dockerfile: "Dockerfile",
+				Context:    ".",
+				SecretFiles: []string{
+					"foo_secret=/path/to/foo_secret",
+				},
+			},
+			want: exec.Command(
+				dockerExe,
+				"build",
+				"--rm=true",
+				"-f",
+				"Dockerfile",
+				"-t",
+				"plugins/drone-docker:latest",
+				".",
+				"--secret id=foo_secret,src=/path/to/foo_secret",
+			),
+		},
+		{
+			name: "multiple mixed secrets",
+			build: Build{
+				Name:       "plugins/drone-docker:latest",
+				Dockerfile: "Dockerfile",
+				Context:    ".",
+				SecretEnvs: []string{
+					"foo_secret=FOO_SECRET_ENV_VAR",
+					"bar_secret=BAR_SECRET_ENV_VAR",
+				},
+				SecretFiles: []string{
+					"foo_secret=/path/to/foo_secret",
+					"bar_secret=/path/to/bar_secret",
+				},
+			},
+			want: exec.Command(
+				dockerExe,
+				"build",
+				"--rm=true",
+				"-f",
+				"Dockerfile",
+				"-t",
+				"plugins/drone-docker:latest",
+				".",
+				"--secret id=foo_secret,env=FOO_SECRET_ENV_VAR",
+				"--secret id=bar_secret,env=BAR_SECRET_ENV_VAR",
+				"--secret id=foo_secret,src=/path/to/foo_secret",
+				"--secret id=bar_secret,src=/path/to/bar_secret",
+			),
+		},
+		{
+			name: "invalid mixed secrets",
+			build: Build{
+				Name:       "plugins/drone-docker:latest",
+				Dockerfile: "Dockerfile",
+				Context:    ".",
+				SecretEnvs: []string{
+					"foo_secret=",
+					"=FOO_SECRET_ENV_VAR",
+					"",
+				},
+				SecretFiles: []string{
+					"foo_secret=",
+					"=/path/to/bar_secret",
+					"",
+				},
+			},
+			want: exec.Command(
+				dockerExe,
+				"build",
+				"--rm=true",
+				"-f",
+				"Dockerfile",
+				"-t",
+				"plugins/drone-docker:latest",
+				".",
+			),
+		},
+	}
+
+	for _, tc := range tcs {
+		tc := tc
+
+		t.Run(tc.name, func(t *testing.T) {
+			cmd := commandBuild(tc.build)
+
+			if !reflect.DeepEqual(cmd.String(), tc.want.String()) {
+				t.Errorf("Got cmd %v, want %v", cmd, tc.want)
+			}
+		})
+	}
+}