Use better flags-docs creator

vertical-pod-autoscaler/hack/generate-flags.sh

@@ -0,0 +1,87 @@
+#!/bin/bash
+
+# Copyright 2025 The Kubernetes 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
+
+SCRIPT_ROOT=$(realpath $(dirname "${BASH_SOURCE[0]}"))/..
+TARGET_FILE="${SCRIPT_ROOT}/docs/flags.md"
+COMPONENTS=("admission-controller" "recommender" "updater")
+
+# Function to extract flags from a binary
+extract_flags() {
+    local binary=$1
+    local component=$2
+
+    if [ ! -f "$binary" ]; then
+        echo "Error: Binary not found for ${component} at ${binary}"
+        return 1
+    fi
+
+    echo "# What are the parameters to VPA ${component}?"
+    echo "This document is auto-generated from the flag definitions in the VPA ${component} code."
+    echo
+    echo "| Flag | Default | Description |"
+    echo "|---------|---------|-------------|"
+
+    $binary --help 2>&1 | grep -E '^\s*-' | while read -r line; do
+        if [[ $line == *"-v, --v Level"* ]]; then
+            # Special handling for the -v, --v Level flag
+            flag="v"
+            default=$(echo "$line" | sed -n 's/.*default: \([0-9]\+\).*/\1/p')
+            description="Set the log level verbosity"
+        else
+            flag=$(echo "$line" | awk '{print $1}' | sed 's/^-*//;s/=.*$//')
+            default=$(echo "$line" | sed -n 's/.*default \([^)]*\).*/\1/p')
+            description=$(echo "$line" | sed -E 's/^\s*-[^[:space:]]+ [^[:space:]]+ //;s/ \(default.*\)//')
+            description=$(echo "$description" | sed -E "s/^--?${flag}[[:space:]]?//")
+        fi
+
+        echo "| \`--${flag}\` | ${default:-} | ${description} |"
+    done
+    echo
+}
+# Build components
+pushd "${SCRIPT_ROOT}" >/dev/null
+for component in "${COMPONENTS[@]}"; do
+    echo "Building ${component}..."
+    pushd "pkg/${component}" >/dev/null
+    if ! go build -o ${component} ; then
+        echo "Error: Failed to build ${component}"
+        popd >/dev/null
+        continue
+    fi
+    popd >/dev/null
+done
+popd >/dev/null
+
+# Generate combined flags documentation
+echo "Generating flags documentation..."
+{
+    echo "# Vertical Pod Autoscaler Flags"
+    echo "This document contains the flags for all VPA components."
+    echo
+
+    for component in "${COMPONENTS[@]}"; do
+        binary="${SCRIPT_ROOT}/pkg/${component}/${component}"
+        if ! extract_flags "$binary" "$component" ; then
+            echo "Error: Failed to extract flags for ${component}"
+        fi
+    done
+} > "${TARGET_FILE}"
+
+echo "VPA flags documentation has been generated in ${TARGET_FILE}"