diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
new file mode 100644
index 00000000..c8a584bc
--- /dev/null
+++ b/CONTRIBUTING.md
@@ -0,0 +1,17 @@
+## Update image gathering scripts
+
+For every release, we'll need to update the image gather scripts for fetching the images used by Knative Charms.
+
+To get an overview of how the script works please read https://github.com/canonical/knative-operators/issues/142
+The script has a limitation on how it's deducing images from upstream manifests, which is tracked in
+https://github.com/canonical/knative-operators/issues/220
+
+The script also needs to gather images for `net-istio`, that has it's own release cadance (although almost 1-1 with Knative Serving, but sometimes tags for Serving might not exist for `net-istio`).
+
+**Process:**
+1. Confirm the Knative Serving version
+2. Deduce the `net-istio` that should be used
+  * If you update based on a Kubeflow release, then you can deduce this from [upstream Kubeflow manifests](https://github.com/kubeflow/manifests/blob/v1.9-branch/common/knative/README.md?plain=1#L8) (make sure to checkout to correct release branch). Note that in the Kubeflow's README this will be referred as `Knative ingress controller for Istio`
+  * If you update to an arbitrary Knative Serving version, then check the branches of [`net-istio`](https://github.com/knative-extensions/net-istio/tags) and pick the closest one to your Knative Serving release
+3. Update the `tools/get-images.sh` script to use the selected version of `net-istio`
+  * If the `net-istio` tag is not 1-1 with the Serving version then hardcode the version of `net-istio` in the script
diff --git a/tools/get-images.sh b/tools/get-images.sh
index e8939da4..93ce0316 100755
--- a/tools/get-images.sh
+++ b/tools/get-images.sh
@@ -1,6 +1,7 @@
 #!/bin/bash
 #
 # This script returns list of container images that are managed by this charm and/or its workload
+set -xe
 
 IMAGE_LIST=()
 IMAGE_LIST+=($(find . -type f -name metadata.yaml -exec yq '.resources | to_entries | .[] | .value | ."upstream-source"' {} \;))
@@ -31,13 +32,10 @@ wget -q "${KNATIVE_SERVING_REPO_DOWNLOAD_URL}/knative-v${KNATIVE_SERVING_VERSION
 SERVING_IMAGE_LIST+=($(yq -N '.spec.template.spec.containers | .[] | .image' ./serving-storage-version-migration.yaml))
 wget -q "${KNATIVE_SERVING_REPO_DOWNLOAD_URL}/knative-v${KNATIVE_SERVING_VERSION}/serving-post-install-jobs.yaml"
 SERVING_IMAGE_LIST+=($(yq -N '.spec.template.spec.containers | .[] | .image' ./serving-post-install-jobs.yaml))
-# obtain net istio images based on hardcoded version
-NET_ISTIO_VERSION="${KNATIVE_SERVING_VERSION}"
-# NOTE: for KNative Serving version 1.10.2 Net Istio version must be set to 1.11.0
-#       this need to be reviewed if KNative Serving version is changed
-if [ $KNATIVE_SERVING_VERSION == "1.10.2" ]; then
-  NET_ISTIO_VERSION="1.11.0"
-fi
+
+# For Serving 1.12.4 (CKF 1.9) we have to use 1.12.3 for net-istio
+# https://github.com/kubeflow/manifests/pull/2709
+NET_ISTIO_VERSION="1.12.3"
 NET_ISTIO_REPO_DOWNLOAD_URL=https://github.com/knative-extensions/net-istio/releases/download/
 NET_ISTIO_IMAGE_LIST=()
 wget -q "${NET_ISTIO_REPO_DOWNLOAD_URL}knative-v${NET_ISTIO_VERSION}/net-istio.yaml"