Allow host mounts for build phahse (knative#2753)

* Allow host mounts for build pahse.

This is in particular useful for using paket bindings,
e.g. to inject git credentials into build process.

Signed-off-by: Matej Vašek <mvasek@redhat.com>

* Mark test as a integration test

Signed-off-by: Matej Vašek <mvasek@redhat.com>

* fixup: style

Signed-off-by: Matej Vašek <mvasek@redhat.com>

---------

Signed-off-by: Matej Vašek <mvasek@redhat.com>

Author: matejvasek

pkg/builders/builders_int_test.go

@@ -1,3 +1,5 @@
+//go:build integration
+
 package builders_test
 
 import (
@@ -35,7 +37,6 @@ import (
 )
 
 func TestPrivateGitRepository(t *testing.T) {
-	t.Skip("tested functionality not implemented yet")
 
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()
@@ -65,6 +66,21 @@ func TestPrivateGitRepository(t *testing.T) {
 		t.Fatal(ctx.Err())
 	}
 
+	gitCredsDir := t.TempDir()
+	err := os.WriteFile(filepath.Join(gitCredsDir, "type"), []byte(`git-credentials`), 0600)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	gitCred := `url=https://git-private.127.0.0.1.sslip.io
+username=developer
+password=nbusr123
+`
+	err = os.WriteFile(filepath.Join(gitCredsDir, "credentials"), []byte(gitCred), 0600)
+	if err != nil {
+		t.Fatal(err)
+	}
+
 	builder := buildpacks.NewBuilder(buildpacks.WithVerbose(true))
 	f, err := fn.NewFunction(filepath.Join("testdata", "go-fn-with-private-deps"))
 	if err != nil {
@@ -73,6 +89,14 @@ func TestPrivateGitRepository(t *testing.T) {
 	f.Build.Image = "localhost:50000/go-app:test"
 	f.Build.Builder = "pack"
 	f.Build.BuilderImages = map[string]string{"pack": builderImage}
+	f.Build.BuildEnvs = []fn.Env{{
+		Name:  ptr("SERVICE_BINDING_ROOT"),
+		Value: ptr("/bindings"),
+	}}
+	f.Build.Mounts = []fn.MountSpec{{
+		Source:      gitCredsDir,
+		Destination: "/bindings/git-binding",
+	}}
 	err = builder.Build(ctx, f, nil)
 	if err != nil {
 		t.Fatal(err)

pkg/builders/buildpacks/builder.go

@@ -179,6 +179,12 @@ func (b *Builder) Build(ctx context.Context, f fn.Function, platforms []fn.Platf
 		opts.ContainerConfig.Network = "host"
 	}
 
+	var bindings = make([]string, 0, len(f.Build.Mounts))
+	for _, m := range f.Build.Mounts {
+		bindings = append(bindings, fmt.Sprintf("%s:%s", m.Source, m.Destination))
+	}
+	opts.ContainerConfig.Volumes = bindings
+
 	// only trust our known builders
 	opts.TrustBuilder = TrustBuilder
 

pkg/functions/function.go

@@ -148,6 +148,14 @@ type BuildSpec struct {
 	// Image stores last built image name NOT in func.yaml, but instead
 	// in .func/built-image
 	Image string `yaml:"-"`
+
+	// Mounts used in build phase. This is useful in particular for paketo bindings.
+	Mounts []MountSpec `yaml:"mounts,omitempty"`
+}
+
+type MountSpec struct {
+	Source      string `yaml:"source"`
+	Destination string `yaml:"destination"`
 }
 
 // RunSpec

schema/func_yaml-schema.json

@@ -48,6 +48,14 @@
 				"remoteStorageClass": {
 					"type": "string",
 					"description": "RemoteStorageClass specifies the storage class to use for the volume used\non-cluster during when built remotely."
+				},
+				"mounts": {
+					"items": {
+						"$schema": "http://json-schema.org/draft-04/schema#",
+						"$ref": "#/definitions/MountSpec"
+					},
+					"type": "array",
+					"description": "Mounts used in build phase. This is useful in particular for paketo bindings."
 				}
 			},
 			"additionalProperties": false,
@@ -269,6 +277,22 @@
 			"additionalProperties": false,
 			"type": "object"
 		},
+		"MountSpec": {
+			"required": [
+				"source",
+				"destination"
+			],
+			"properties": {
+				"source": {
+					"type": "string"
+				},
+				"destination": {
+					"type": "string"
+				}
+			},
+			"additionalProperties": false,
+			"type": "object"
+		},
 		"Options": {
 			"properties": {
 				"scale": {