update-kustomizations.sh

#!/usr/bin/env bash

# This script will go through all kustomization files, looking for image tag
# changes such as the following:
# images:
#   - name: ghcr.io/alexgustafsson/cupdate
#     newTag: 0.24.2
#
# For all such images, the script will perform a lookup towards Cupdate's API to
# find the latest image and update the manifest in-place if the user whishes to
# do so.

# CUPDATE_API must be set to the URL where your Cupdate instance is reachable
CUPDATE_API="https://cupdate.home.local/api/v1/images"
# MANIFEST_FILE_NAME is the name of kustomization files. All files by this name
# in current directory will be checked
MANIFEST_FILE_NAME="kustomization.yaml"

function confirm() {
	while true; do
		echo -n "$1 [Y/n] "
		read -rsn 1 result </dev/tty
		echo
		case "$result" in
		'y' | 'Y' | '')
			return 0
			;;
		'n' | 'N')
			return 1
			;;
		*)
			continue
			;;
		esac
	done
}

# For each kustomization file found in the current directory
while read -r kustomization; do
	# For each image reference tag replacement found in the kustomization, such as
	# images:
	#   - name: ghcr.io/alexgustafsson/cupdate
	#     newTag: 0.24.2
	while read -r reference; do
		if [[ -z "$reference" ]]; then
			continue
		fi

		# Use the Cupdate API to find the latest reference
		latestReference="$(curl --silent --get "$CUPDATE_API?query=$reference" | jq -rc .images[0].latestReference 2>/dev/null | sed 's/@sha256:.*//')"
		if [[ ! $! -eq 0 ]] || [[ -z "$latestReference" ]] || [[ "$latestReference" = "$reference" ]] || [[ "$latestReference" = "null" ]]; then
			continue
		fi

		# Print a header and ask for confirmation
		echo "$kustomization"
		echo -e "\e[31m$reference\e[0m -> \e[32m$latestReference\e[0m"
		confirm "Update?"

		# If update is confirmed
		if [[ $? -eq 0 ]]; then
			# Parse reference
			name=${reference%%:*}
			version=${reference#*:}
			latestVersion=${latestReference#*:}

			# Create a diff using yq as yq doesn't support keeping whitespace or
			# comments around
			diff="$(diff -u --ignore-blank-lines -L "$kustomization" -L "$kustomization" <(grep -v '^$' "$kustomization") <(yq ".images[] |= select(.name == \"$name\" and .newTag == \"$version\").newTag = \"$latestVersion\"" "$kustomization"))"
			# Print and apply the diff
			echo "$diff"
			echo "$diff" | patch --silent --unified --posix --fuzz 3 "$kustomization" -i -
		fi

		# Separate runs by a newline
		echo
	done <<<"$(yq '.images[] | select((.name|type == "!!str") and (.newTag|type == "!!str")) | "\(.name):\(.newTag)"' "$kustomization" | grep -v '^:$')"
done <<<"$(find . -type f -name "$MANIFEST_FILE_NAME")"