engine.#LoadSecret support

Fixes #1305

Signed-off-by: Andrea Luzzardi <aluzzardi@gmail.com>

docs/reference/europa/dagger/engine.md

@@ -138,6 +138,18 @@ _No input._
 
 _No output._
 
+## engine.#LoadSecret
+
+Load a secret from a filesystem tree
+
+### engine.#LoadSecret Inputs
+
+_No input._
+
+### engine.#LoadSecret Outputs
+
+_No output._
+
 ## engine.#Merge
 
 Merge multiple FS trees into one

plan/task/loadsecret.go

@@ -0,0 +1,54 @@
+package task
+
+import (
+	"context"
+	"fmt"
+	"io/fs"
+	"strings"
+
+	"go.dagger.io/dagger/compiler"
+	"go.dagger.io/dagger/plancontext"
+	"go.dagger.io/dagger/solver"
+)
+
+func init() {
+	Register("LoadSecret", func() Task { return &loadSecretTask{} })
+}
+
+type loadSecretTask struct {
+}
+
+func (t *loadSecretTask) Run(ctx context.Context, pctx *plancontext.Context, s solver.Solver, v *compiler.Value) (*compiler.Value, error) {
+	path, err := v.Lookup("path").String()
+	if err != nil {
+		return nil, err
+	}
+
+	input, err := pctx.FS.FromValue(v.Lookup("input"))
+	if err != nil {
+		return nil, err
+	}
+	inputFS := solver.NewBuildkitFS(input.Result())
+
+	// FIXME: we should create an intermediate image containing only `path`.
+	// That way, on cache misses, we'll only download the layer with the file contents rather than the entire FS.
+	contents, err := fs.ReadFile(inputFS, path)
+	if err != nil {
+		return nil, fmt.Errorf("ReadFile %s: %w", path, err)
+	}
+	plaintext := string(contents)
+
+	trimSpace, err := v.Lookup("trimSpace").Bool()
+	if err != nil {
+		return nil, err
+	}
+	if trimSpace {
+		plaintext = strings.TrimSpace(plaintext)
+	}
+
+	secret := pctx.Secrets.New(plaintext)
+
+	return compiler.NewValue().FillFields(map[string]interface{}{
+		"contents": secret.MarshalCUE(),
+	})
+}

stdlib/europa/dagger/engine/secret.cue

@@ -0,0 +1,15 @@
+package engine
+
+// Load a secret from a filesystem tree
+#LoadSecret: {
+	$dagger: task: _name: "LoadSecret"
+
+	// Filesystem tree holding the secret
+	input: #FS
+	// Path of the secret to read
+	path: string
+	// Whether to trim leading and trailing space characters from secret value
+	trimSpace: *true | false
+	// Contents of the secret
+	contents: #Secret
+}

tests/tasks.bats

@@ -125,3 +125,9 @@ setup() {
     run "$DAGGER" --europa up ./tasks/httpfetch/not_exist.cue
     assert_failure
 }
+
+@test "task: #LoadSecret" {
+    cd "$TESTDIR"/tasks/loadsecret
+
+    "$DAGGER" --europa up ./loadsecret.cue
+}

tests/tasks/loadsecret/loadsecret.cue

@@ -0,0 +1,37 @@
+package main
+
+import (
+	"alpha.dagger.io/europa/dagger/engine"
+)
+
+engine.#Plan & {
+	actions: {
+		image: engine.#Pull & {
+			source: "alpine:3.15.0@sha256:e7d88de73db3d3fd9b2d63aa7f447a10fd0220b7cbf39803c803f2af9ba256b3"
+		}
+
+		generate: engine.#Exec & {
+			input: image.output
+			args: ["sh", "-c", "echo test > /secret"]
+		}
+
+		load: engine.#LoadSecret & {
+			input: generate.output
+			path:  "/secret"
+		}
+
+		verify: engine.#Exec & {
+			input: image.output
+			mounts: secret: {
+				dest:     "/run/secrets/test"
+				contents: load.contents
+			}
+			args: [
+				"sh", "-c",
+				#"""
+					test "$(cat /run/secrets/test)" = "test"
+					"""#,
+			]
+		}
+	}
+}