Updates version of go used to build buildpack from source on CF

bin/finalize

@@ -13,7 +13,7 @@ output_dir=$(mktemp -d -t finalizeXXX)
 
 echo "-----> Running go build finalize"
 pushd $BUILDPACK_DIR
-GOROOT=$GoInstallDir/go $GoInstallDir/go/bin/go build -mod=vendor -o $output_dir/finalize ./src/binary/finalize/cli
+GOROOT=$GoInstallDir $GoInstallDir/bin/go build -mod=vendor -o $output_dir/finalize ./src/binary/finalize/cli
 popd
 
 $output_dir/finalize "$BUILD_DIR" "$CACHE_DIR" "$DEPS_DIR" "$DEPS_IDX" "$PROFILE_DIR"

bin/supply

@@ -12,7 +12,7 @@ output_dir=$(mktemp -d -t supplyXXX)
 
 echo "-----> Running go build supply"
 pushd $BUILDPACK_DIR
-GOROOT=$GoInstallDir/go $GoInstallDir/go/bin/go build -mod=vendor -o $output_dir/supply ./src/binary/supply/cli
+GOROOT=$GoInstallDir $GoInstallDir/bin/go build -mod=vendor -o $output_dir/supply ./src/binary/supply/cli
 popd
 
 $output_dir/supply "$BUILD_DIR" "$CACHE_DIR" "$DEPS_DIR" "$DEPS_IDX"

go.mod

@@ -5,7 +5,7 @@ require (
 	github.com/nxadm/tail v1.4.5 // indirect
 	github.com/onsi/ginkgo v1.14.2
 	github.com/onsi/gomega v1.10.3
-	golang.org/x/sys v0.0.0-20201130171929-760e229fe7c5 // indirect
+	golang.org/x/sys v0.0.0-20201202213521-69691e467435 // indirect
 )
 
 go 1.13

go.sum

@@ -543,6 +543,8 @@ golang.org/x/sys v0.0.0-20200523222454-059865788121/go.mod h1:h1NjWce9XRLGQEsW7w
 golang.org/x/sys v0.0.0-20200930185726-fdedc70b468f/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20201130171929-760e229fe7c5 h1:dMDtAap8F/+vsyXblqK90iTzYJjNix5MsXDicSYol6w=
 golang.org/x/sys v0.0.0-20201130171929-760e229fe7c5/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20201202213521-69691e467435 h1:25AvDqqB9PrNqj1FLf2/70I4W0L19qqoaFq3gjNwbKk=
+golang.org/x/sys v0.0.0-20201202213521-69691e467435/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/text v0.0.0-20160726164857-2910a502d2bf/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.0.0-20170915032832-14c0d48ead0c/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.0 h1:g61tztE5qeGQ89tm6NTjjM9VPIm088od1l6aSorWRWg=

scripts/install_go.sh

@@ -2,10 +2,10 @@
 
 set -euo pipefail
 
-GO_VERSION="1.12.4"
+GO_VERSION="1.15.5"
 
 if [ $CF_STACK == "cflinuxfs3" ]; then
-    GO_SHA256="e68279204493307782c51105c3dd5254ab066d0b5d9aafa3ce3a2878ebbef53f"
+    GO_SHA256="fd04494f7a2dd478b0d31cb949aae7f154749cae1242581b1574f7e590b3b7e6"
 else
   echo "       **ERROR** Unsupported stack"
   echo "                 See https://docs.cloudfoundry.org/devguide/deploy-apps/stacks.html for more info"
@@ -16,22 +16,23 @@ export GoInstallDir="/tmp/go$GO_VERSION"
 mkdir -p $GoInstallDir
 
 if [ ! -f $GoInstallDir/go/bin/go ]; then
-  URL=https://buildpacks.cloudfoundry.org/dependencies/go/go${GO_VERSION}.linux-amd64-${CF_STACK}-${GO_SHA256:0:8}.tar.gz
+  URL=https://buildpacks.cloudfoundry.org/dependencies/go/go_${GO_VERSION}_linux_x64_${CF_STACK}_${GO_SHA256:0:8}.tgz
 
   echo "-----> Download go ${GO_VERSION}"
-  curl -s -L --retry 15 --retry-delay 2 $URL -o /tmp/go.tar.gz
+  curl -s -L --retry 15 --retry-delay 2 $URL -o /tmp/go.tgz
 
-  DOWNLOAD_SHA256=$(shasum -a 256 /tmp/go.tar.gz | cut -d ' ' -f 1)
+  DOWNLOAD_SHA256=$(shasum -a 256 /tmp/go.tgz | cut -d ' ' -f 1)
 
   if [[ $DOWNLOAD_SHA256 != $GO_SHA256 ]]; then
     echo "       **ERROR** SHA256 mismatch: got $DOWNLOAD_SHA256 expected $GO_SHA256"
     exit 1
   fi
 
-  tar xzf /tmp/go.tar.gz -C $GoInstallDir
-  rm /tmp/go.tar.gz
+  tar xzf /tmp/go.tgz -C $GoInstallDir
+  rm /tmp/go.tgz
 fi
-if [ ! -f $GoInstallDir/go/bin/go ]; then
+
+if [ ! -f $GoInstallDir/bin/go ]; then
   echo "       **ERROR** Could not download go"
   exit 1
 fi