updated docker_package_check.sh

docker/docker_package_check.sh

@@ -23,8 +23,8 @@ srcdir="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 
 # shellcheck disable=SC2034,SC2154
 usage_description="
-Runs package installs on all the major versions of a given docker image to check given packages
-are available before adding them and breaking builds across distro versions
+Runs package installs on the last 8 major versions of a given docker image to check given packages are available
+before adding them and breaking builds across distro versions
 
 Uses adjacent scripts:
 
@@ -34,6 +34,8 @@ Uses adjacent scripts:
 
 to install the packages using whatever local package manager is detected
 
+Set environment variable MAX_VERSIONS to change the number of distro versions to run against (default: 8)
+
 Currently only supports DockerHub images
 "
 
@@ -48,6 +50,12 @@ min_args 2 "$@"
 image="$1"
 shift || :
 
+max_versions="${MAX_VERSIONS:-8}"
+
+if ! is_int "$max_versions"; then
+    die "MAX_VERSIONS may only be set to an integer, not: $max_versions"
+fi
+
 check_bin docker
 
 if [[ "$image" =~ alpine ]]; then
@@ -74,6 +82,8 @@ if grep -Eq '^[[:digit:]]+$' <<< "$major_versions"; then
     major_versions="$(grep -EO -e '^[[:digit:]]+$' -e 'latest' <<< "$major_versions" | sort -Vr)"
 fi
 
+major_versions="$(head -n "$max_versions" <<< "$major_versions")"
+
 echo
 timestamp "Running for major versions:"
 echo