feat: Add support for build-secrets

Enables passing of build-secrets through the 'secrets' block inside
'build'.
The feature is only available when using Buildkit.

docs/resources/image.md

@@ -132,6 +132,7 @@ Optional:
 - `pull_parent` (Boolean) Attempt to pull the image even if an older image exists locally
 - `remote_context` (String) A Git repository URI or HTTP/HTTPS context URI
 - `remove` (Boolean) Remove intermediate containers after a successful build. Defaults to `true`.
+- `secrets` (Block List) Set build-time secrets (see [below for nested schema](#nestedblock--build--secrets))
 - `security_opt` (List of String) The security options
 - `session_id` (String) Set an ID for the build session
 - `shm_size` (Number) Size of /dev/shm in bytes. The size must be greater than 0
@@ -160,6 +161,19 @@ Optional:
 - `user_name` (String) the registry user name
 
 
+<a id="nestedblock--build--secrets"></a>
+### Nested Schema for `build.secrets`
+
+Required:
+
+- `id` (String) ID of the secret. By default, secrets are mounted to /run/secrets/<id>
+
+Optional:
+
+- `env` (String) Environment variable source of the secret
+- `src` (String) File source of the secret
+
+
 <a id="nestedblock--build--ulimit"></a>
 ### Nested Schema for `build.ulimit`
 

go.mod

@@ -218,6 +218,7 @@ require (
 	github.com/timonwong/loggercheck v0.9.3 // indirect
 	github.com/tomarrell/wrapcheck/v2 v2.6.2 // indirect
 	github.com/tommy-muehle/go-mnd/v2 v2.5.0 // indirect
+	github.com/tonistiigi/units v0.0.0-20180711220420-6950e57a87ea // indirect
 	github.com/ultraware/funlen v0.0.3 // indirect
 	github.com/ultraware/whitespace v0.0.5 // indirect
 	github.com/uudashr/gocognit v1.0.6 // indirect

go.sum

@@ -1158,6 +1158,8 @@ github.com/tomarrell/wrapcheck/v2 v2.6.2 h1:3dI6YNcrJTQ/CJQ6M/DUkc0gnqYSIk6o0rCh
 github.com/tomarrell/wrapcheck/v2 v2.6.2/go.mod h1:ao7l5p0aOlUNJKI0qVwB4Yjlqutd0IvAB9Rdwyilxvg=
 github.com/tommy-muehle/go-mnd/v2 v2.5.0 h1:iAj0a8e6+dXSL7Liq0aXPox36FiN1dBbjA6lt9fl65s=
 github.com/tommy-muehle/go-mnd/v2 v2.5.0/go.mod h1:WsUAkMJMYww6l/ufffCD3m+P7LEvr8TnZn9lwVDlgzw=
+github.com/tonistiigi/units v0.0.0-20180711220420-6950e57a87ea h1:SXhTLE6pb6eld/v/cCndK0AMpt1wiVFb/YYmqB3/QG0=
+github.com/tonistiigi/units v0.0.0-20180711220420-6950e57a87ea/go.mod h1:WPnis/6cRcDZSUvVmezrxJPkiO87ThFYsoUiMwWNDJk=
 github.com/ugorji/go v1.1.4/go.mod h1:uQMGLiO92mf5W77hV/PUCpI3pbzQx3CRekS0kk+RGrc=
 github.com/ultraware/funlen v0.0.3 h1:5ylVWm8wsNwH5aWo9438pwvsK0QiqVuUrt9bn7S/iLA=
 github.com/ultraware/funlen v0.0.3/go.mod h1:Dp4UiAus7Wdb9KUZsYWZEWiRzGuM2kXM1lPbfaF6xhA=

internal/provider/resource_docker_image.go

@@ -97,6 +97,36 @@ func resourceDockerImage() *schema.Resource {
 							},
 							ForceNew: true,
 						},
+						"secrets": {
+							Type:        schema.TypeList,
+							Description: "Set build-time secrets",
+							Optional:    true,
+							Elem: &schema.Resource{
+								Schema: map[string]*schema.Schema{
+									"id": {
+										Type:        schema.TypeString,
+										Description: "ID of the secret. By default, secrets are mounted to /run/secrets/<id>",
+										Optional:    false,
+										Required:    true,
+										ForceNew:    true,
+									},
+									"src": {
+										Type:        schema.TypeString,
+										Description: "File source of the secret",
+										Optional:    true,
+										Required:    false,
+										ForceNew:    true,
+									},
+									"env": {
+										Type:        schema.TypeString,
+										Description: "Environment variable source of the secret",
+										Optional:    true,
+										Required:    false,
+										ForceNew:    true,
+									},
+								},
+							},
+						},
 						"label": {
 							Type:        schema.TypeMap,
 							Description: "Set metadata for an image",

internal/provider/resource_docker_image_funcs.go

@@ -24,6 +24,7 @@ import (
 	"github.com/hashicorp/terraform-plugin-sdk/v2/helper/schema"
 	"github.com/mitchellh/go-homedir"
 	"github.com/moby/buildkit/session"
+	"github.com/moby/buildkit/session/secrets/secretsprovider"
 	"github.com/pkg/errors"
 )
 
@@ -333,7 +334,22 @@ func buildDockerImage(ctx context.Context, rawBuild map[string]interface{}, imag
 
 	buildContext := rawBuild["context"].(string)
 
-	enableBuildKitIfSupported(ctx, client, &buildOptions)
+	buildKitSession := enableBuildKitIfSupported(ctx, client, &buildOptions)
+
+	// If Buildkit is enabled, try to parse and use secrets if present.
+	if buildKitSession != nil {
+		if secretsRaw, secretsDefined := rawBuild["secrets"]; secretsDefined {
+			parsedSecrets := parseBuildSecrets(secretsRaw)
+
+			store, err := secretsprovider.NewStore(parsedSecrets)
+			if err != nil {
+				return err
+			}
+
+			provider := secretsprovider.NewSecretProvider(store)
+			buildKitSession.Allow(provider)
+		}
+	}
 
 	buildCtx, relDockerfile, err := prepareBuildContext(buildContext, buildOptions.Dockerfile)
 	if err != nil {
@@ -355,7 +371,11 @@ func buildDockerImage(ctx context.Context, rawBuild map[string]interface{}, imag
 	return nil
 }
 
-func enableBuildKitIfSupported(ctx context.Context, client *client.Client, buildOptions *types.ImageBuildOptions) {
+func enableBuildKitIfSupported(
+	ctx context.Context,
+	client *client.Client,
+	buildOptions *types.ImageBuildOptions,
+) *session.Session {
 	dockerClientVersion := client.ClientVersion()
 	log.Printf("[DEBUG] DockerClientVersion: %v, minBuildKitDockerVersion: %v\n", dockerClientVersion, minBuildkitDockerVersion)
 	if versions.GreaterThanOrEqualTo(dockerClientVersion, minBuildkitDockerVersion) {
@@ -369,8 +389,10 @@ func enableBuildKitIfSupported(ctx context.Context, client *client.Client, build
 		defer s.Close()
 		buildOptions.SessionID = s.ID()
 		buildOptions.Version = types.BuilderBuildKit
+		return s
 	} else {
 		buildOptions.Version = types.BuilderV1
+		return nil
 	}
 }
 
@@ -452,3 +474,20 @@ func decodeBuildMessages(response types.ImageBuildResponse) (string, error) {
 
 	return buf.String(), buildErr
 }
+
+func parseBuildSecrets(secretsRaw interface{}) []secretsprovider.Source {
+	options := secretsRaw.([]interface{})
+
+	secrets := make([]secretsprovider.Source, len(options))
+	for i, option := range options {
+		secretRaw := option.(map[string]interface{})
+		source := secretsprovider.Source{
+			ID:       secretRaw["id"].(string),
+			FilePath: secretRaw["src"].(string),
+			Env:      secretRaw["env"].(string),
+		}
+		secrets[i] = source
+	}
+
+	return secrets
+}

internal/provider/resource_docker_image_test.go

@@ -449,6 +449,53 @@ func TestAccDockerImage_build(t *testing.T) {
 	})
 }
 
+func TestAccDockerImageSecrets_build(t *testing.T) {
+	const testDockerFileWithSecret = `
+	FROM python:3-stretch
+
+	WORKDIR /app
+
+	ARG test_arg
+
+	RUN echo ${test_arg} > test_arg.txt
+
+	RUN --mount=type=secret,id=TEST_SECRET_SRC \
+        --mount=type=secret,id=TEST_SECRET_ENV \
+		apt-get update -qq`
+
+	ctx := context.Background()
+	wd, _ := os.Getwd()
+	dfPath := filepath.Join(wd, "Dockerfile")
+	if err := ioutil.WriteFile(dfPath, []byte(testDockerFileWithSecret), 0o644); err != nil {
+		t.Fatalf("failed to create a Dockerfile %s for test: %+v", dfPath, err)
+	}
+	defer os.Remove(dfPath)
+
+	const secretContent = "THIS IS A SECRET"
+	sPath := filepath.Join(wd, "secret")
+	if err := ioutil.WriteFile(sPath, []byte(secretContent), 0o644); err != nil {
+		t.Fatalf("failed to create a secret file %s for test: %+v", sPath, err)
+	}
+
+	defer os.Remove(sPath)
+
+	resource.Test(t, resource.TestCase{
+		PreCheck:          func() { testAccPreCheck(t) },
+		ProviderFactories: providerFactories,
+		CheckDestroy: func(state *terraform.State) error {
+			return testAccDockerImageDestroy(ctx, state)
+		},
+		Steps: []resource.TestStep{
+			{
+				Config: loadTestConfiguration(t, RESOURCE, "docker_image", "testDockerImageBuildSecrets"),
+				Check: resource.ComposeTestCheckFunc(
+					resource.TestMatchResourceAttr("docker_image.test", "name", contentDigestRegexp),
+				),
+			},
+		},
+	})
+}
+
 const testDockerFileExample = `
 FROM python:3-bookworm
 

testdata/resources/docker_image/testDockerImageBuildSecrets.tf

@@ -0,0 +1,18 @@
+resource "docker_image" "test" {
+  name = "ubuntu:11"
+  build {
+    context      = "."
+    dockerfile   = "Dockerfile"
+    force_remove = true
+
+    secrets {
+      id  = "TEST_SECRET_SRC"
+      src = "./secret"
+    }
+
+    secrets {
+      id  = "TEST_SECRET_ENV"
+      env = "PATH"
+    }
+  }
+}