Merge pull request #4270 from jsternberg/invalid-caching-multiple-bin…

…d-mounts

solver: correctly set the content selector with multiple bind mounts references

solver/llbsolver/ops/exec.go

@@ -227,16 +227,28 @@ func (e *ExecOp) getMountDeps() ([]dep, error) {
 			return nil, errors.Errorf("invalid mountinput %v", m)
 		}
 
-		sel := m.Selector
-		if sel != "" {
-			sel = path.Join("/", sel)
-			deps[m.Input].Selectors = append(deps[m.Input].Selectors, sel)
-		}
+		// Mark the selector path as used. In this section, we need to
+		// record root selectors so the selection criteria isn't narrowed
+		// erroneously.
+		sel := path.Join("/", m.Selector)
+		deps[m.Input].Selectors = append(deps[m.Input].Selectors, sel)
 
 		if (!m.Readonly || m.Dest == pb.RootMount) && m.Output != -1 { // exclude read-only rootfs && read-write mounts
 			deps[m.Input].NoContentBasedHash = true
 		}
 	}
+
+	// Remove extraneous selectors that may have been generated from above.
+	for i, dep := range deps {
+		for _, sel := range dep.Selectors {
+			// If the root path is included in the list of selectors,
+			// this is the same as if no selector was used. Zero out this field.
+			if sel == "/" {
+				deps[i].Selectors = nil
+				break
+			}
+		}
+	}
 	return deps, nil
 }
 

solver/llbsolver/ops/exec_test.go

@@ -3,6 +3,9 @@ package ops
 import (
 	"testing"
 
+	"github.com/moby/buildkit/solver"
+	"github.com/moby/buildkit/solver/pb"
+	digest "github.com/opencontainers/go-digest"
 	"github.com/stretchr/testify/require"
 )
 
@@ -25,3 +28,72 @@ func TestDedupPaths(t *testing.T) {
 	res = dedupePaths([]string{"foo/bar/baz", "foo/bara", "foo/bar/bax", "foo/bar"})
 	require.Equal(t, []string{"foo/bar", "foo/bara"}, res)
 }
+
+func TestExecOp_getMountDeps(t *testing.T) {
+	v1 := &vertex{name: "local://context"}
+	v2 := &vertex{
+		name: "foo",
+		inputs: []solver.Edge{
+			{Vertex: v1, Index: 0},
+		},
+	}
+	op2, err := NewExecOp(v2, &pb.Op_Exec{
+		Exec: &pb.ExecOp{
+			Meta: &pb.Meta{
+				Args: []string{"/bin/bash", "-l"},
+			},
+			Mounts: []*pb.Mount{
+				{
+					Input:    pb.Empty,
+					Dest:     "/",
+					Readonly: true,
+					Output:   pb.SkipOutput,
+				},
+				{
+					Input:    pb.InputIndex(0),
+					Selector: "b.txt",
+					Dest:     "/test/b.txt",
+					Output:   pb.SkipOutput,
+				},
+				{
+					Input:  pb.InputIndex(0),
+					Dest:   "/test/data",
+					Output: pb.SkipOutput,
+				},
+			},
+		},
+	}, nil, nil, nil, nil, nil, nil)
+	require.NoError(t, err)
+
+	deps, err := op2.getMountDeps()
+	require.NoError(t, err)
+
+	require.Len(t, deps, 1)
+	require.Len(t, deps[0].Selectors, 0)
+	require.False(t, deps[0].NoContentBasedHash)
+}
+
+type vertex struct {
+	name   string
+	inputs []solver.Edge
+}
+
+func (v *vertex) Digest() digest.Digest {
+	return digest.FromString(v.name)
+}
+
+func (v *vertex) Sys() interface{} {
+	return v
+}
+
+func (v *vertex) Options() solver.VertexOptions {
+	return solver.VertexOptions{}
+}
+
+func (v *vertex) Inputs() []solver.Edge {
+	return v.inputs
+}
+
+func (v *vertex) Name() string {
+	return v.name
+}