Update Cargo/crates.io Sparse Index support

The environment variable for Cargo/crates.io sparse index support has changed to `CARGO_REGISTRIES_CRATES_IO_PROTOCOL=sparse`. This PR updates that functionality. It is still enabled by default, but requires beta or nightly Rust to work. This should just start working when upstream Rust supports this in stable.

Signed-off-by: Daniel Mikusa <[email protected]>

cargo/cargo.go

@@ -216,8 +216,8 @@ func (c Cargo) Contribute(layer libcnb.Layer) (libcnb.Layer, error) {
 			return libcnb.Layer{}, fmt.Errorf("unable to find CARGO_HOME, it must be set")
 		}
 
-		if err := os.Setenv("CARGO_UNSTABLE_SPARSE_REGISTRY", "true"); err != nil {
-			return libcnb.Layer{}, fmt.Errorf("unable to set CARGO_UNSTABLE_SPARSE_REGISTRY\n%w", err)
+		if err := os.Setenv("CARGO_REGISTRIES_CRATES_IO_PROTOCOL", "sparse"); err != nil {
+			return libcnb.Layer{}, fmt.Errorf("unable to set CARGO_REGISTRIES_CRATES_IO_PROTOCOL\n%w", err)
 		}
 
 		if err = preserver.RestoreAll(targetPath, cargoHome, layer.Path); err != nil {

cargo/cargo_test.go

@@ -293,7 +293,7 @@ func testCargo(t *testing.T, context spec.G, it spec.S) {
 				_, err = c.Contribute(inputLayer)
 				Expect(err).NotTo(HaveOccurred())
 
-				Expect(os.Getenv("CARGO_UNSTABLE_SPARSE_REGISTRY")).To(Equal("true"))
+				Expect(os.Getenv("CARGO_REGISTRIES_CRATES_IO_PROTOCOL")).To(Equal("sparse"))
 
 				Expect(service.Calls[2].Method).To(Equal("InstallTool"))
 				Expect(service.Calls[2].Arguments[0]).To(Equal("foo-tool"))
@@ -343,7 +343,7 @@ func testCargo(t *testing.T, context spec.G, it spec.S) {
 				outputLayer, err := c.Contribute(inputLayer)
 				Expect(err).NotTo(HaveOccurred())
 
-				Expect(os.Getenv("CARGO_UNSTABLE_SPARSE_REGISTRY")).To(Equal("true"))
+				Expect(os.Getenv("CARGO_REGISTRIES_CRATES_IO_PROTOCOL")).To(Equal("sparse"))
 
 				sbomScanner.AssertCalled(t, "ScanLayer", inputLayer, ctx.Application.Path, libcnb.CycloneDXJSON, libcnb.SyftJSON)
 
@@ -390,7 +390,7 @@ func testCargo(t *testing.T, context spec.G, it spec.S) {
 				outputLayer, err := c.Contribute(inputLayer)
 				Expect(err).NotTo(HaveOccurred())
 
-				Expect(os.Getenv("CARGO_UNSTABLE_SPARSE_REGISTRY")).To(Equal("true"))
+				Expect(os.Getenv("CARGO_REGISTRIES_CRATES_IO_PROTOCOL")).To(Equal("sparse"))
 
 				sbomScanner.AssertCalled(t, "ScanLayer", inputLayer, ctx.Application.Path, libcnb.CycloneDXJSON, libcnb.SyftJSON)
 
@@ -437,7 +437,7 @@ func testCargo(t *testing.T, context spec.G, it spec.S) {
 				outputLayer, err := c.Contribute(inputLayer)
 				Expect(err).NotTo(HaveOccurred())
 
-				Expect(os.Getenv("CARGO_UNSTABLE_SPARSE_REGISTRY")).To(Equal("true"))
+				Expect(os.Getenv("CARGO_REGISTRIES_CRATES_IO_PROTOCOL")).To(Equal("sparse"))
 
 				sbomScanner.AssertNotCalled(t, "ScanLayer", inputLayer, ctx.Application.Path, libcnb.CycloneDXJSON, libcnb.SyftJSON)
 
@@ -489,7 +489,7 @@ func testCargo(t *testing.T, context spec.G, it spec.S) {
 					outputLayer, err := c.Contribute(inputLayer)
 					Expect(err).NotTo(HaveOccurred())
 
-					Expect(os.Getenv("CARGO_UNSTABLE_SPARSE_REGISTRY")).To(Equal("true"))
+					Expect(os.Getenv("CARGO_REGISTRIES_CRATES_IO_PROTOCOL")).To(Equal("sparse"))
 
 					sbomScanner.AssertCalled(t, "ScanLayer", inputLayer, ctx.Application.Path, libcnb.CycloneDXJSON, libcnb.SyftJSON)
 
@@ -539,7 +539,7 @@ func testCargo(t *testing.T, context spec.G, it spec.S) {
 				outputLayer, err := c.Contribute(inputLayer)
 				Expect(err).NotTo(HaveOccurred())
 
-				Expect(os.Getenv("CARGO_UNSTABLE_SPARSE_REGISTRY")).To(Equal("true"))
+				Expect(os.Getenv("CARGO_REGISTRIES_CRATES_IO_PROTOCOL")).To(Equal("sparse"))
 
 				sbomScanner.AssertCalled(t, "ScanLayer", inputLayer, ctx.Application.Path, libcnb.CycloneDXJSON, libcnb.SyftJSON)
 
@@ -653,7 +653,7 @@ func testCargo(t *testing.T, context spec.G, it spec.S) {
 				outputLayer, err := c.Contribute(inputLayer)
 				Expect(err).NotTo(HaveOccurred())
 
-				Expect(os.Getenv("CARGO_UNSTABLE_SPARSE_REGISTRY")).To(Equal("true"))
+				Expect(os.Getenv("CARGO_REGISTRIES_CRATES_IO_PROTOCOL")).To(Equal("sparse"))
 
 				Expect(outputLayer.LayerTypes.Cache).To(BeTrue())
 				Expect(outputLayer.LayerTypes.Build).To(BeFalse())