Buildpacks builder supports mounting read/write volumes (experimental) (

#5972)

docs/content/en/schemas/v2beta17.json

@@ -628,6 +628,10 @@
           "description": "indicates that the builder should be trusted.",
           "x-intellij-html-description": "indicates that the builder should be trusted.",
           "default": "false"
+        },
+        "volumes": {
+          "description": "support mounting host volumes into the container.",
+          "x-intellij-html-description": "support mounting host volumes into the container."
         }
       },
       "preferredOrder": [
@@ -637,7 +641,8 @@
         "buildpacks",
         "trustBuilder",
         "projectDescriptor",
-        "dependencies"
+        "dependencies",
+        "volumes"
       ],
       "additionalProperties": false,
       "type": "object",
@@ -674,6 +679,38 @@
       "description": "*alpha* used to specify dependencies for an artifact built by buildpacks.",
       "x-intellij-html-description": "<em>alpha</em> used to specify dependencies for an artifact built by buildpacks."
     },
+    "BuildpackVolume": {
+      "required": [
+        "host",
+        "target"
+      ],
+      "properties": {
+        "host": {
+          "type": "string",
+          "description": "local volume or absolute directory of the path to mount.",
+          "x-intellij-html-description": "local volume or absolute directory of the path to mount."
+        },
+        "options": {
+          "type": "string",
+          "description": "specify a list of comma-separated mount options. Valid options are: `ro` (default): volume contents are read-only. `rw`: volume contents are readable and writable. `volume-opt=<key>=<value>`: can be specified more than once, takes a key-value pair.",
+          "x-intellij-html-description": "specify a list of comma-separated mount options. Valid options are: <code>ro</code> (default): volume contents are read-only. <code>rw</code>: volume contents are readable and writable. <code>volume-opt=&lt;key&gt;=&lt;value&gt;</code>: can be specified more than once, takes a key-value pair."
+        },
+        "target": {
+          "type": "string",
+          "description": "path where the file or directory is available in the container. It is strongly recommended to not specify locations under `/cnb` or `/layers`.",
+          "x-intellij-html-description": "path where the file or directory is available in the container. It is strongly recommended to not specify locations under <code>/cnb</code> or <code>/layers</code>."
+        }
+      },
+      "preferredOrder": [
+        "host",
+        "target",
+        "options"
+      ],
+      "additionalProperties": false,
+      "type": "object",
+      "description": "*alpha* used to mount host volumes or directories in the build container.",
+      "x-intellij-html-description": "<em>alpha</em> used to mount host volumes or directories in the build container."
+    },
     "ClusterDetails": {
       "properties": {
         "HTTPS_PROXY": {

pkg/skaffold/build/buildpacks/lifecycle.go

@@ -72,6 +72,12 @@ func (b *Builder) build(ctx context.Context, out io.Writer, a *latestV1.Artifact
 	if err != nil {
 		return "", fmt.Errorf("unable to evaluate env variables: %w", err)
 	}
+
+	cc, err := containerConfig(artifact)
+	if err != nil {
+		return "", fmt.Errorf("%q: %w", a.ImageName, err)
+	}
+
 	// List buildpacks to be used for the build.
 	// Those specified in the skaffold.yaml replace those in the project.toml.
 	buildpacks := artifact.Buildpacks
@@ -92,14 +98,15 @@ func (b *Builder) build(ctx context.Context, out io.Writer, a *latestV1.Artifact
 	builderImage, runImage, pullPolicy := resolveDependencyImages(artifact, b.artifacts, a.Dependencies, b.pushImages)
 
 	if err := runPackBuildFunc(ctx, output.GetUnderlyingWriter(out), b.localDocker, pack.BuildOptions{
-		AppPath:      workspace,
-		Builder:      builderImage,
-		RunImage:     runImage,
-		Buildpacks:   buildpacks,
-		Env:          env,
-		Image:        latest,
-		PullPolicy:   pullPolicy,
-		TrustBuilder: artifact.TrustBuilder,
+		AppPath:         workspace,
+		Builder:         builderImage,
+		RunImage:        runImage,
+		Buildpacks:      buildpacks,
+		Env:             env,
+		Image:           latest,
+		PullPolicy:      pullPolicy,
+		TrustBuilder:    artifact.TrustBuilder,
+		ContainerConfig: cc,
 		// TODO(dgageot): Support project.toml include/exclude.
 		// FileFilter: func(string) bool { return true },
 	}); err != nil {
@@ -231,3 +238,23 @@ func resolveDependencyImages(artifact *latestV1.BuildpackArtifact, r ArtifactRes
 
 	return builderImage, runImage, pullPolicy
 }
+
+func containerConfig(artifact *latestV1.BuildpackArtifact) (pack.ContainerConfig, error) {
+	var vols []string
+	if artifact.Volumes != nil {
+		for _, v := range *artifact.Volumes {
+			if v.Host == "" || v.Target == "" {
+				// in case these slip by the JSON schema
+				return pack.ContainerConfig{}, errors.New("buildpacks volumes must have both host and target")
+			}
+			var spec string
+			if v.Options == "" {
+				spec = fmt.Sprintf("%s:%s", v.Host, v.Target)
+			} else {
+				spec = fmt.Sprintf("%s:%s:%s", v.Host, v.Target, v.Options)
+			}
+			vols = append(vols, spec)
+		}
+	}
+	return pack.ContainerConfig{Volumes: vols}, nil
+}

pkg/skaffold/build/buildpacks/lifecycle_test.go

@@ -22,6 +22,10 @@ import (
 	"testing"
 
 	lifecycle "github.com/buildpacks/lifecycle/cmd"
+	"github.com/buildpacks/pack"
+
+	latestV1 "github.com/GoogleContainerTools/skaffold/pkg/skaffold/schema/latest/v1"
+	"github.com/GoogleContainerTools/skaffold/testutil"
 )
 
 func TestLifecycleStatusCode(t *testing.T) {
@@ -61,3 +65,51 @@ func TestLifecycleStatusCode(t *testing.T) {
 		}
 	}
 }
+
+func TestContainerConfig(t *testing.T) {
+	tests := []struct {
+		description string
+		volumes     []latestV1.BuildpackVolume
+		shouldErr   bool
+		expected    pack.ContainerConfig
+	}{
+		{
+			description: "single volume with no options",
+			volumes:     []latestV1.BuildpackVolume{{Host: "/foo", Target: "/bar"}},
+			expected:    pack.ContainerConfig{Volumes: []string{"/foo:/bar"}},
+		},
+		{
+			description: "single volume with  options",
+			volumes:     []latestV1.BuildpackVolume{{Host: "/foo", Target: "/bar", Options: "rw"}},
+			expected:    pack.ContainerConfig{Volumes: []string{"/foo:/bar:rw"}},
+		},
+		{
+			description: "multiple volumes",
+			volumes: []latestV1.BuildpackVolume{
+				{Host: "/foo", Target: "/bar", Options: "rw"},
+				{Host: "/bat", Target: "/baz", Options: "ro"},
+			},
+			expected: pack.ContainerConfig{Volumes: []string{"/foo:/bar:rw", "/bat:/baz:ro"}},
+		},
+		{
+			description: "missing host is skipped",
+			volumes:     []latestV1.BuildpackVolume{{Host: "", Target: "/bar"}},
+			shouldErr:   true,
+		},
+		{
+			description: "missing target is skipped",
+			volumes:     []latestV1.BuildpackVolume{{Host: "/foo", Target: ""}},
+			shouldErr:   true,
+		},
+	}
+
+	for _, test := range tests {
+		testutil.Run(t, test.description, func(t *testutil.T) {
+			artifact := latestV1.BuildpackArtifact{
+				Volumes: &test.volumes,
+			}
+			result, err := containerConfig(&artifact)
+			t.CheckErrorAndDeepEqual(test.shouldErr, err, test.expected, result)
+		})
+	}
+}

pkg/skaffold/schema/latest/v1/config.go

@@ -994,6 +994,9 @@ type BuildpackArtifact struct {
 
 	// Dependencies are the file dependencies that skaffold should watch for both rebuilding and file syncing for this artifact.
 	Dependencies *BuildpackDependencies `yaml:"dependencies,omitempty"`
+
+	// Volumes support mounting host volumes into the container.
+	Volumes *[]BuildpackVolume `yaml:"volumes,omitempty"`
 }
 
 // BuildpackDependencies *alpha* is used to specify dependencies for an artifact built by buildpacks.
@@ -1006,6 +1009,23 @@ type BuildpackDependencies struct {
 	Ignore []string `yaml:"ignore,omitempty"`
 }
 
+// BuildpackVolume *alpha* is used to mount host volumes or directories in the build container.
+type BuildpackVolume struct {
+	// Host is the local volume or absolute directory of the path to mount.
+	Host string `yaml:"host" skaffold:"filepath" yamltags:"required"`
+
+	// Target is the path where the file or directory is available in the container.
+	// It is strongly recommended to not specify locations under `/cnb` or `/layers`.
+	Target string `yaml:"target" yamltags:"required"`
+
+	// Options specify a list of comma-separated mount options.
+	// Valid options are:
+	// `ro` (default): volume contents are read-only.
+	// `rw`: volume contents are readable and writable.
+	// `volume-opt=<key>=<value>`: can be specified more than once, takes a key-value pair.
+	Options string `yaml:"options,omitempty"`
+}
+
 // CustomArtifact *beta* describes an artifact built from a custom build script
 // written by the user. It can be used to build images with builders that aren't directly integrated with skaffold.
 type CustomArtifact struct {