engine.#WriteFile

Signed-off-by: Joel Longtine <joel@dagger.io>

plan/task/writefile.go

@@ -0,0 +1,90 @@
+package task
+
+import (
+	"context"
+	"fmt"
+	"io/fs"
+
+	"cuelang.org/go/cue"
+	"github.com/moby/buildkit/client/llb"
+	"go.dagger.io/dagger/compiler"
+	"go.dagger.io/dagger/plancontext"
+	"go.dagger.io/dagger/solver"
+)
+
+func init() {
+	Register("WriteFile", func() Task { return &writeFileTask{} })
+}
+
+type writeFileTask struct {
+}
+
+func (t *writeFileTask) Run(ctx context.Context, pctx *plancontext.Context, s solver.Solver, v *compiler.Value) (*compiler.Value, error) {
+	var contents []byte
+	var err error
+
+	path, err := v.Lookup("path").String()
+	if err != nil {
+		return nil, err
+	}
+
+	switch kind := v.Lookup("contents").Kind(); kind {
+	// TODO: support bytes?
+	// case cue.BytesKind:
+	// 	contents, err = v.Lookup("contents").Bytes()
+	case cue.StringKind:
+		var str string
+		str, err = v.Lookup("contents").String()
+		if err == nil {
+			contents = []byte(str)
+		}
+	case cue.BottomKind:
+		err = fmt.Errorf("%s: WriteFile contents is not set", path)
+	default:
+		err = fmt.Errorf("%s: unhandled data type in WriteFile: %s", path, kind)
+	}
+
+	if err != nil {
+		return nil, err
+	}
+
+	mode, err := v.Lookup("mode").Int64()
+
+	// err = fmt.Errorf("%s: unhandled data type in WriteFile: %w", path, err)
+	if err != nil {
+		return nil, err
+	}
+
+	input, err := pctx.FS.FromValue(v.Lookup("input"))
+
+	if err != nil {
+		return nil, err
+	}
+
+	inputState, err := input.Result().ToState()
+
+	if err != nil {
+		return nil, err
+	}
+
+	outputState := inputState.File(
+		llb.Mkfile(path, fs.FileMode(mode), contents),
+		withCustomName(v, "WriteFile %s", path),
+	)
+
+	result, err := s.Solve(ctx, outputState, pctx.Platform.Get())
+
+	if err != nil {
+		return nil, err
+	}
+
+	fs := pctx.FS.New(result)
+
+	output := compiler.NewValue()
+
+	if err := output.FillPath(cue.ParsePath("output"), fs.MarshalCUE()); err != nil {
+		return nil, err
+	}
+
+	return output, nil
+}

stdlib/europa/dagger/engine/fs.cue

@@ -8,3 +8,13 @@ package engine
 	contents: string
 	output:   #FS
 }
+
+#WriteFile: {
+	_type: "WriteFile"
+
+	input:    #FS
+	path:     string
+	contents: string
+	mode:     int
+	output:   #FS
+}

tests/cue.mod/module.cue

@@ -0,0 +1 @@
+module: ""

tests/cue.mod/pkg/.gitignore

@@ -0,0 +1,3 @@
+# generated by dagger
+alpha.dagger.io
+dagger.lock

tests/tasks.bats

@@ -12,4 +12,15 @@ setup() {
 @test "task: #ReadFile" {
     cd "$TESTDIR"/tasks/readfile
     dagger --europa up
+}
+
+@test "task: #WriteFile" {
+    cd "$TESTDIR"
+    dagger --europa up ./tasks/write_file/write_file.cue
+}
+
+@test "task: #WriteFile failure: different contents" {
+    cd "$TESTDIR"
+    run dagger --europa up ./tasks/write_file/write_file_failure_diff_contents.cue
+    assert_failure 
 }

tests/tasks/write_file/cue.mod/module.cue

@@ -0,0 +1 @@
+module: ""

tests/tasks/write_file/cue.mod/pkg/.gitignore

@@ -0,0 +1,3 @@
+# generated by dagger
+alpha.dagger.io
+dagger.lock

tests/tasks/write_file/write_file.cue

@@ -0,0 +1,26 @@
+package main
+
+import (
+	"alpha.dagger.io/dagger/engine"
+)
+
+engine.#Plan & {
+	actions: {
+		pull: engine.#Pull & {
+			source: "alpine:3.15.0@sha256:e7d88de73db3d3fd9b2d63aa7f447a10fd0220b7cbf39803c803f2af9ba256b3"
+		}
+		write: engine.#WriteFile & {
+			input:    pull.output
+			path:     "/testing"
+			contents: "1,2,3"
+			mode:     700
+		}
+		readfile: engine.#ReadFile & {
+			input: write.output
+			path:  "/testing"
+		} & {
+			// assert result
+			contents: "1,2,3"
+		}
+	}
+}

tests/tasks/write_file/write_file_failure_diff_contents.cue

@@ -0,0 +1,26 @@
+package main
+
+import (
+	"alpha.dagger.io/dagger/engine"
+)
+
+engine.#Plan & {
+	actions: {
+		pull: engine.#Pull & {
+			source: "alpine:3.15.0@sha256:e7d88de73db3d3fd9b2d63aa7f447a10fd0220b7cbf39803c803f2af9ba256b3"
+		}
+		write: engine.#WriteFile & {
+			input:    pull.output
+			path:     "/testing"
+			contents: "1,2,3,4"
+			mode:     700
+		}
+		readfile: engine.#ReadFile & {
+			input: write.output
+			path:  "/testing"
+		} & {
+			// assert result
+			contents: "1,2,3"
+		}
+	}
+}