Merge pull request #331 from dagger/fix-double-exec

Fixed duplicated execution on `op.#Exec.always: true`

dagger/pipeline.go

@@ -385,13 +385,10 @@ func (p *Pipeline) Exec(ctx context.Context, op *compiler.Value, st llb.State) (
 	}
 
 	// always?
-	// FIXME: initialize once for an entire compute job, to avoid cache misses
 	if cmd.Always {
-		cacheBuster, err := randomID(8)
+		// FIXME: also disables persistent cache directories
-		if err != nil {
+		// There's an ongoing proposal that would fix this: https://github.com/moby/buildkit/issues/1213
-			return st, err
+		opts = append(opts, llb.IgnoreCache)
-		}
-		opts = append(opts, llb.AddEnv("DAGGER_CACHEBUSTER", cacheBuster))
 	}
 	// mounts
 	if mounts := op.Lookup("mount"); mounts.Exists() {

dagger/utils.go

@@ -1,15 +0,0 @@
-package dagger
-
-import (
-	"crypto/rand"
-	"fmt"
-)
-
-func randomID(size int) (string, error) {
-	b := make([]byte, size)
-	_, err := rand.Read(b)
-	if err != nil {
-		return "", err
-	}
-	return fmt.Sprintf("%x", b), nil
-}

stdlib/aws/elb/elb.cue

@@ -19,9 +19,7 @@ import (
 	out: string
 
 	aws.#Script & {
-		// FIXME: we should not rely on the cache for this but it's being
+		always: true
-		// executed several times if enabled: https://github.com/dagger/dagger/issues/42
-		// always: true
 
 		files: {
 			"/inputs/listenerArn": listenerArn

stdlib/dagger/op/op.cue

@@ -45,6 +45,7 @@ package op
 	do: "exec"
 	args: [...string]
 	env?: [string]: string
+	// `true` means also ignoring the mount cache volumes
 	always?: true | *false
 	dir:     string | *"/"
 	mount: [string]: "tmpfs" | "cache" | {from: _, path: string | *"/"}

tests/compute/success/exec-nocache/main.cue

@@ -0,0 +1,25 @@
+package main
+
+import (
+	"dagger.io/alpine"
+	"dagger.io/dagger/op"
+)
+
+rand: {
+	string
+
+	#up: [
+		op.#Load & {from: alpine.#Image},
+		op.#Exec & {
+			always: true
+			args: ["sh", "-c", """
+				tr -dc A-Za-z0-9 </dev/urandom | head -c 13 > /id
+				"""]
+		},
+		op.#Export & {source: "/id"},
+	]
+}
+
+// If rand is executed twice, cue won't validate
+ref1: rand
+ref2: ref1

tests/test-compute.sh

@@ -35,6 +35,8 @@ test::compute::simple(){
       "$dagger" "${DAGGER_BINARY_ARGS[@]}" compute "$d"/compute/success/overload/flat
   test::one "Compute: overloading #Component should work" --exit=0  \
       "$dagger" "${DAGGER_BINARY_ARGS[@]}" compute "$d"/compute/success/overload/wrapped
+  test::one "Compute: Disabling the cache on exec should not compute twice when referenced by another key" --exit=0  \
+      "$dagger" "${DAGGER_BINARY_ARGS[@]}" compute "$d"/compute/success/exec-nocache
 }
 
 test::compute::dependencies(){