Change the release builder to build ko. (#991)

Despite using an upgraded go image in certain steps, the ko image that
Kf was using to build still had an outdated version of go (1.17) meaning
that there was an inconsistency between local development and what was
being produced.

This change pivots us to use the latest version of ko on the current go
base image the pipeline uses ensuring Kf will always be built with an
expected version of Go, allowing us to stay up to date on features and
patches.

Author: josephlewis42

cmd/generate-release/cloudbuild.yaml

@@ -30,10 +30,10 @@ substitutions:
   _EXTRA_TAG: ''      # Defaults to _VERSION
   _RELEASE_BUCKET: '' # Required
   _RELEASE_FOLDER: '' # Defaults to _VERSION
-  _KO_IMAGE: 'gcr.io/kf-releases/ko:latest'
   _CLOUDSDK_IMAGE: 'gcr.io/google.com/cloudsdktool/cloud-sdk:alpine'
   _GOLANG_IMAGE: 'golang:1.20'
   _BUILDPACK_WRAPPER_GOLANG_IMAGE: 'golang:1.15'
+  _KO_VERSION: 'github.com/google/ko@latest'
 
 timeout: '1800s'
 
@@ -43,7 +43,7 @@ options:
 steps:
 - id: check substitutions
   entrypoint: bash
-  name: "${_KO_IMAGE}"
+  name: "${_GOLANG_IMAGE}"
   args:
   - '-euc'
   - |
@@ -156,7 +156,7 @@ steps:
     done
 
 - id: generate v2 lifecycle image artifacts
-  name: "${_KO_IMAGE}"
+  name: "${_GOLANG_IMAGE}"
   dir: /workspace
   waitFor: ['push third party image']
   env:
@@ -184,7 +184,7 @@ steps:
       vendor/code.cloudfoundry.org/buildpackapplifecycle/installer/kodata
 
 - id: generate Kf Release
-  name: "${_KO_IMAGE}"
+  name: "${_GOLANG_IMAGE}"
   dir: /workspace
   waitFor: ['push third party image']
   env:
@@ -206,7 +206,10 @@ steps:
     # Test the main directories to force go mod to update everything.
     # go test ./cmd/...
     sed -i "s|PROJECT_PLACEHOLDER|${PROJECT_ID}|g" config/config-defaults.yaml
-    /builder/ko.bash resolve --filename config | sed "s/VERSION_PLACEHOLDER/$${VERSION}/" > /workspace/bin/kf.yaml
+
+    go install "${_KO_VERSION}"
+
+    ko resolve --filename config | sed "s/VERSION_PLACEHOLDER/$${VERSION}/" > /workspace/bin/kf.yaml
 
     # Append empty config-secrets to kf release.
     # The Operator need this to exist so the configmap transformers can do their work.
@@ -223,7 +226,7 @@ steps:
     EOF
 
 - id: generate kf Operator Release
-  name: "${_KO_IMAGE}"
+  name: "${_GOLANG_IMAGE}"
   dir: /workspace/operator
   waitFor: ['generate Kf Release']
   env:
@@ -267,7 +270,9 @@ steps:
     mkdir "${target_dir}"
     cp /workspace/bin/kf.yaml "${target_dir}"
 
-    /builder/ko.bash resolve --filename config > /workspace/bin/operator.yaml
+    go install "${_KO_VERSION}"
+
+    ko resolve --filename config > /workspace/bin/operator.yaml
 
     cp /workspace/cmd/generate-release/scripts/kfsystems-cr.yaml /workspace/bin/kfsystem.yaml