Add AL23 ref doc and install specific go version

buildspecs/pr-build-amzn.yml

@@ -8,7 +8,7 @@ env:
 phases:
   install:
     commands:
-      # Same buildspec used for different Amazon Linuc versions - detect verison to use in Go installation
+      # Same buildspec used for different Amazon Linux versions - detect verison to use in Go installation
       - |
         if [ -f /etc/os-release ]; then
           . /etc/os-release
@@ -41,25 +41,30 @@ phases:
         esac
 
       # Identify the correct AL2023 version to use in the Go installation
+      # Ref: https://docs.aws.amazon.com/linux/al2023/ug/managing-repos-os-updates.html
+      # xmllint is required to find the latest distribution release from releasemd.xml in us-west-2
       - AL23_VERSION="$(curl -s https://al2023-repos-us-west-2-de612dc2.s3.dualstack.us-west-2.amazonaws.com/core/releasemd.xml | xmllint --xpath "string(//root/releases/release[last()]/@version)" -)"
       - AGENT_VERSION=$(cat VERSION)
 
       # Need to install GOLANG explicitly as required versions do not come preinstalled
-      # Remove existing go installation (goenv utility) and install downloaded binaries
+      # Remove existing go installation (goenv utility)
       - sudo rm -rf /root/.goenv
       - sudo rm -rf /usr/local/go/bin/go 
 
-      # Install dependencies and define variables based on the build image used
+      # Define the Go version to install
+      - GOVERSION="$(cat GO_VERSION)"
+
+      # Install Go and define variables based on Amazon Linux version (2 or 2023)
       # Amazon Linux 2023 uses package manager DNF, while older versions use YUM
       # Set the appropriate AL23 version echo string to include in build log
       - |
         if [[ "$amzn_version" = "amzn2023" ]]; then
           sudo dnf --releasever="$AL23_VERSION" update -y
-          sudo yum install -y golang
+          sudo yum install -y golang-$GOVERSION
           amzn_version="amzn2023"
           al23_version_echo="Amazon Linux 2023 Version: $AL23_VERSION"
         elif [[ "$amzn_version" = "amzn2" ]]; then
-          sudo yum install -y golang
+          sudo yum install -y golang-$GOVERSION
           amzn_version="amzn2"
           al23_version_echo=""
         else