Add KOCACHE support to CI workflows

Pre-cache ko base images from .ko.yaml to reduce build times and network usage during CI runs.

Co-Authored-By: Vincent Demeester <vincent@sbr.pm>
Signed-off-by: Vibhav Bobade <vibhav.bobde@gmail.com>

Author: waveywaves

.github/workflows/ci.yaml

@@ -103,6 +103,9 @@ jobs:
       with:
         go-version-file: "go.mod"
     - uses: ko-build/setup-ko@d006021bd0c28d1ce33a07e7943d48b079944c8d # v0.9
+    - uses: imjasonh/setup-crane@31b88efe9de28ae0ffa220711af4b60be9435f6e # v0.4
+    - name: Cache ko base images
+      run: ./hack/cache-ko-base-images.sh
     - name: ko-resolve
       run: |
           # Use the repository's .ko.yaml for consistent base images

.github/workflows/e2e-matrix.yml

@@ -115,6 +115,10 @@ jobs:
       with:
         go-version-file: "go.mod"
     - uses: ko-build/setup-ko@d006021bd0c28d1ce33a07e7943d48b079944c8d # v0.9
+    - uses: imjasonh/setup-crane@31b88efe9de28ae0ffa220711af4b60be9435f6e # v0.4
+
+    - name: Cache ko base images
+      run: ./hack/cache-ko-base-images.sh
 
     - name: Install Dependencies
       working-directory: ./

hack/cache-ko-base-images.sh

@@ -0,0 +1,104 @@
+#!/usr/bin/env bash
+
+# Copyright 2025 The Tekton Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+set -o errexit
+set -o nounset
+set -o pipefail
+
+# Print error message and exit 1
+# Parameters: $1..$n - error message to be displayed
+function abort() {
+    echo "error: $*" >&2
+    exit 1
+}
+
+# Check if crane is available
+if ! command -v crane &>/dev/null; then
+    abort "crane command not found. Please install it from https://github.com/google/go-containerregistry"
+fi
+
+# Check if .ko.yaml exists
+if [[ ! -f ".ko.yaml" ]]; then
+    abort ".ko.yaml file not found in current directory"
+fi
+
+# Set default KOCACHE if not set
+KOCACHE="${KOCACHE:-${HOME}/.ko}"
+
+# Create output directory if it doesn't exist
+IMG_DIR="${KOCACHE}/img"
+mkdir -p "${IMG_DIR}"
+
+# Extract images with digests from .ko.yaml
+# Look for lines containing @sha256: or @sha512: followed by a digest
+# Extract the image reference (everything from start of image to end of digest, ignoring comments)
+DIGEST_IMAGES=()
+
+while IFS= read -r line; do
+    # Skip comments and empty lines
+    line_trimmed=$(echo "${line}" | sed 's/#.*$//' | sed 's/^[[:space:]]*//' | sed 's/[[:space:]]*$//')
+    if [[ -z "${line_trimmed}" ]]; then
+        continue
+    fi
+
+    # Extract image references with digests
+    # Pattern: match image refs like registry/repo:tag@sha256:digest or registry/repo@sha256:digest
+    if echo "${line_trimmed}" | grep -qE '@sha(256|512):[a-f0-9]+'; then
+        # Extract the value part after the colon (for YAML key: value)
+        if echo "${line_trimmed}" | grep -qE '^[^:]+:[[:space:]]+'; then
+            # YAML key: value format - extract the value
+            image=$(echo "${line_trimmed}" | sed -E 's/^[^:]+:[[:space:]]+//' | sed 's/#.*$//' | sed 's/[[:space:]]*$//')
+            # Check if it's an image with digest
+            if echo "${image}" | grep -qE '@sha(256|512):[a-f0-9]+'; then
+                DIGEST_IMAGES+=("${image}")
+            fi
+        else
+            # Might be standalone or in a different format, try to extract directly
+            image=$(echo "${line_trimmed}" | grep -oE '[^[:space:]]+@sha(256|512):[a-f0-9]+' | head -1)
+            if [[ -n "${image}" ]]; then
+                DIGEST_IMAGES+=("${image}")
+            fi
+        fi
+    fi
+done <.ko.yaml
+
+if [[ ${#DIGEST_IMAGES[@]} -eq 0 ]]; then
+    echo "No images with digests found in .ko.yaml"
+    exit 0
+fi
+
+# Remove duplicates
+IFS=$'\n' sorted_unique_images=($(sort -u <<<"${DIGEST_IMAGES[*]}"))
+unset IFS
+
+echo "Found ${#sorted_unique_images[@]} unique image(s) with digests in .ko.yaml:"
+for img in "${sorted_unique_images[@]}"; do
+    echo "  - ${img}"
+done
+echo ""
+
+# Pull each image
+for image in "${sorted_unique_images[@]}"; do
+    echo "Pulling ${image}..."
+    if crane pull --format oci "${image}" "${IMG_DIR}"; then
+        echo "Successfully pulled ${image} to ${IMG_DIR}"
+    else
+        abort "Failed to pull ${image}"
+    fi
+done
+
+echo ""
+echo "All images have been pulled to ${IMG_DIR}"