feat: add script to manage hpa (#1318)

Author: rackerchris

scripts/manage_hpa.sh

@@ -0,0 +1,240 @@
+#!/bin/bash
+
+# --- Configuration ---
+# Default file to store the original HPA settings for reversal
+DEFAULT_HPA_CONFIG_FILE="hpa_originals.json"
+# Name of the temporary patch file
+PATCH_FILE="hpa-patch.json"
+
+# --- Global Parameter ---
+DRY_RUN=false
+
+# --- Functions ---
+
+# Function to safely exit on error and cleanup
+function safe_exit {
+    echo "ERROR: $1" >&2
+    if [ -f "$PATCH_FILE" ]; then
+        rm -f "$PATCH_FILE"
+    fi
+    exit 1
+}
+
+# Function to execute kubectl patch based on DRY_RUN mode
+function execute_patch {
+    local NAME="$1"
+    local NAMESPACE="$2"
+    local PATCH_TYPE="$3"
+    local PATCH_FILE_NAME="$4"
+    local ACTION_DESC="$5"
+
+    if $DRY_RUN; then
+        echo "  [DRY-RUN] Would have executed: kubectl patch hpa $NAME -n $NAMESPACE --type=$PATCH_TYPE --patch-file=$PATCH_FILE_NAME"
+        echo "  [DRY-RUN] Patch Content:"
+        cat "$PATCH_FILE_NAME" | sed 's/^/    /' 
+        echo "  [DRY-RUN] Action: $ACTION_DESC"
+        return 0
+    else
+        echo "  -> Applying patch: $ACTION_DESC"
+        if kubectl patch hpa "$NAME" -n "$NAMESPACE" --type="$PATCH_TYPE" --patch-file="$PATCH_FILE_NAME"; then
+            return 0
+        else
+            return 1
+        fi
+    fi
+}
+
+# Function to display current HPA state (used in dry-run)
+function display_current_hpa_state {
+    echo "--- CURRENT LIVE HPA STATE ---"
+    
+    # Check for the lock file status
+    if [ -f "$1" ]; then
+        echo "Lock Status: LOCKED (Config file $1 EXISTS)"
+    else
+        echo "Lock Status: UNLOCKED (Config file $1 does NOT exist)"
+    fi
+    
+    # Display the current HPA table
+    kubectl get hpa --all-namespaces --no-headers -o=custom-columns='NAMESPACE:.metadata.namespace,NAME:.metadata.name,REPLICAS:.status.currentReplicas,MIN_REPLICAS:.spec.minReplicas,MAX_REPLICAS:.spec.maxReplicas' | awk '
+    BEGIN {
+        printf "%-20s %-30s %-10s %-12s %-12s\n", "NAMESPACE", "NAME", "CURRENT", "MIN_LIVE", "MAX_LIVE"
+        print "-------------------- ------------------------------ ---------- ------------ ------------"
+    }
+    { printf "%-20s %-30s %-10s %-12s %-12s\n", $1, $2, $3, $4, $5 }
+    '
+    echo "----------------------------------------------------------------------------------------"
+}
+
+
+# --- LOCK MODE: Save and Set MaxReplicas = MinReplicas ---
+function lock_hpas {
+    local HPA_CONFIG_FILE="$1"
+    
+    if $DRY_RUN; then
+        display_current_hpa_state "$HPA_CONFIG_FILE"
+    fi
+
+    if [ -f "$HPA_CONFIG_FILE" ] && ! $DRY_RUN; then
+        safe_exit "The lock file ($HPA_CONFIG_FILE) already exists. Run 'unlock' first, or delete the file manually if the operation was interrupted."
+    fi
+
+    echo "--- HPA LOCK MODE: Disabling Scaling ---"
+    echo "Using config file: $HPA_CONFIG_FILE"
+    
+    echo "1. Retrieving current HPA configurations..."
+    HPA_DATA=$(kubectl get hpa --all-namespaces -o json || safe_exit "Failed to retrieve HPA configs. Check kubectl access.")
+
+    HPA_ORIGINALS=$(echo "$HPA_DATA" | jq '[
+        .items[] | select(.spec.minReplicas and .spec.maxReplicas) | {
+            namespace: .metadata.namespace, 
+            name: .metadata.name, 
+            original_min: .spec.minReplicas, 
+            original_max: .spec.maxReplicas
+        }
+    ]')
+
+    if [ "$(echo "$HPA_ORIGINALS" | jq '. | length')" -eq 0 ]; then
+        echo "No HPA resources found to process. Exiting."
+        exit 0
+    fi
+
+    if ! $DRY_RUN; then
+        echo "$HPA_ORIGINALS" > "$HPA_CONFIG_FILE"
+        echo "2. Successfully saved original settings to: $HPA_CONFIG_FILE"
+    else
+        echo "2. [DRY-RUN] Would have saved original settings to: $HPA_CONFIG_FILE"
+    fi
+
+    echo "3. Patching HPAs to lock scaling (maxReplicas = minReplicas)..."
+    
+    echo "$HPA_ORIGINALS" | jq -c '.[]' | while read -r HPA_ITEM; do
+        NAMESPACE=$(echo "$HPA_ITEM" | jq -r '.namespace')
+        NAME=$(echo "$HPA_ITEM" | jq -r '.name')
+        MIN_REPLICAS=$(echo "$HPA_ITEM" | jq -r '.original_min')
+        ORIGINAL_MAX=$(echo "$HPA_ITEM" | jq -r '.original_max')
+        
+        ACTION_DESC="Setting maxReplicas from $ORIGINAL_MAX to $MIN_REPLICAS"
+
+        PATCH_CONTENT=$(cat <<EOF
+[
+  { "op": "replace", "path": "/spec/maxReplicas", "value": $MIN_REPLICAS }
+]
+EOF
+        )
+        echo "$PATCH_CONTENT" > "$PATCH_FILE"
+
+        if ! execute_patch "$NAME" "$NAMESPACE" "json" "$PATCH_FILE" "$ACTION_DESC"; then
+            safe_exit "Failed to patch HPA $NAME in namespace $NAMESPACE."
+        fi
+        rm -f "$PATCH_FILE"
+    done
+    
+    echo "---"
+    if $DRY_RUN; then
+        echo "HPA Lock Dry Run Complete. NO changes were applied to the cluster."
+    else
+        echo "HPA Lock Complete. The cluster is ready for maintenance."
+    fi
+}
+
+# --- UNLOCK MODE: Restore Original MaxReplicas ---
+function unlock_hpas {
+    local HPA_CONFIG_FILE="$1"
+    
+    if $DRY_RUN; then
+        display_current_hpa_state "$HPA_CONFIG_FILE"
+    fi
+    
+    echo "--- HPA UNLOCK MODE: Restoring Scaling ---"
+    echo "Using config file: $HPA_CONFIG_FILE"
+    
+    if [ ! -f "$HPA_CONFIG_FILE" ]; then
+        safe_exit "Original config file $HPA_CONFIG_FILE not found. Cannot proceed with unlock. Did you run 'lock' first?"
+    fi
+
+    echo "1. Reading original settings from $HPA_CONFIG_FILE"
+    HPA_ORIGINALS=$(cat "$HPA_CONFIG_FILE")
+
+    echo "2. Patching HPAs to restore original maxReplicas..."
+    
+    echo "$HPA_ORIGINALS" | jq -c '.[]' | while read -r HPA_ITEM; do
+        NAMESPACE=$(echo "$HPA_ITEM" | jq -r '.namespace')
+        NAME=$(echo "$HPA_ITEM" | jq -r '.name')
+        ORIGINAL_MAX=$(echo "$HPA_ITEM" | jq -r '.original_max')
+        ORIGINAL_MIN=$(echo "$HPA_ITEM" | jq -r '.original_min')
+        
+        ACTION_DESC="Setting maxReplicas from $ORIGINAL_MIN to $ORIGINAL_MAX (Restoring HPA)"
+
+        PATCH_CONTENT=$(cat <<EOF
+[
+  { "op": "replace", "path": "/spec/maxReplicas", "value": $ORIGINAL_MAX }
+]
+EOF
+        )
+        echo "$PATCH_CONTENT" > "$PATCH_FILE"
+
+        if ! execute_patch "$NAME" "$NAMESPACE" "json" "$PATCH_FILE" "$ACTION_DESC"; then
+            safe_exit "Failed to restore HPA $NAME in namespace $NAMESPACE."
+        fi
+        rm -f "$PATCH_FILE"
+    done
+
+    if ! $DRY_RUN; then
+        rm -f "$HPA_CONFIG_FILE"
+        echo "3. Successfully removed the original config file: $HPA_CONFIG_FILE"
+    else
+        echo "3. [DRY-RUN] Would have removed the original config file: $HPA_CONFIG_FILE"
+    fi
+    
+    echo "---"
+    if $DRY_RUN; then
+        echo "HPA Unlock Dry Run Complete. NO changes were applied to the cluster."
+    else
+        echo "HPA Unlock Complete. Scaling is re-enabled."
+    fi
+}
+
+# --- Script Execution and Parameter Handling ---
+
+ARGS=()
+for arg in "$@"; do
+    if [ "$arg" == "--dry-run" ]; then
+        DRY_RUN=true
+        echo "========================================="
+        echo "!!! DRY RUN MODE ENABLED - NO CHANGES WILL BE APPLIED !!!"
+        echo "========================================="
+    else
+        ARGS+=("$arg")
+    fi
+done
+
+if [ "${#ARGS[@]}" -lt 1 ] || [ "${#ARGS[@]}" -gt 2 ]; then
+    echo "Usage: $0 {lock|unlock} [OPTIONAL_CONFIG_FILE] [--dry-run]"
+    echo "  {lock|unlock}: The operation mode."
+    echo "  [OPTIONAL_CONFIG_FILE]: The file to store/read HPA settings (defaults to $DEFAULT_HPA_CONFIG_FILE)."
+    echo "  [--dry-run]: Optional flag to simulate changes without execution."
+    exit 1
+fi
+
+MODE="${ARGS[0]}"
+
+if [ "${#ARGS[@]}" -eq 2 ]; then
+    HPA_CONFIG_FILE="${ARGS[1]}"
+else
+    HPA_CONFIG_FILE="$DEFAULT_HPA_CONFIG_FILE"
+fi
+
+case "$MODE" in
+    lock)
+        lock_hpas "$HPA_CONFIG_FILE"
+        ;;
+    unlock)
+        unlock_hpas "$HPA_CONFIG_FILE"
+        ;;
+    *)
+        echo "Invalid argument: $MODE"
+        echo "Usage: $0 {lock|unlock} [OPTIONAL_CONFIG_FILE] [--dry-run]"
+        exit 1
+        ;;
+esac