Calculates eviction signals used by kubelet to trigger eviction manager

calculate-kubernetes-eviction-signals.sh

# Calculate Eviction Signals - Current State vs Threshold:
#
#  https://kubernetes.io/docs/concepts/scheduling-eviction/node-pressure-eviction/#eviction-signals
#  https://medium.com/kubernetes-tutorials/efficient-node-out-of-resource-management-in-kubernetes-67f158da6e59
#
NODES=($(kubectl get nodes -o jsonpath='{.items[*].metadata.name}'))
NODE_COUNT=${#NODES[@]}

while true;
do
  for ((i=1; i<=${NODE_COUNT}; i++)); do
    NODE=${NODES[$i-1]}
    # =======
    # Refresh
    # =======
    CURRENT_PAYLOAD=$(kubectl get --raw "/api/v1/nodes/${NODE}/proxy/stats/summary");
    THRESHOLD_PAYLOAD=$(kubectl get --raw "/api/v1/nodes/${NODE}/proxy/configz");

    # ====================
    # Current Calculations
    # ====================
    # -- 1. Memory --
    MEMORY_AVAILABLE_BYTES=$(echo ${CURRENT_PAYLOAD} | jq .node.memory.availableBytes);
    # MB
    MEMORY_AVAILABLE_MB=$(echo "scale=2; ${MEMORY_AVAILABLE_BYTES}/1024/1024" | bc);

    # -- 2. Nodefs capacity --
    NODEFS_AVAILABLE_BYTES=$(echo ${CURRENT_PAYLOAD} | jq .node.fs.availableBytes);
    NODEFS_CAPACITY_BYTES=$(echo ${CURRENT_PAYLOAD} | jq .node.fs.capacityBytes);
    # GB
    NODEFS_AVAILABLE_GB=$(echo "scale=2; ${NODEFS_AVAILABLE_BYTES}/1024/1024/1024" | bc);
    NODEFS_CAPACITY_GB=$(echo "scale=2; ${NODEFS_CAPACITY_BYTES}/1024/1024/1024" | bc);
    # %
    NODEFS_PERCENTAGE=$(echo "scale=2; ${NODEFS_AVAILABLE_GB}/${NODEFS_CAPACITY_GB}*100" | bc);

    # -- 3. Nodefs Inodes --
    NODEFS_INODES_AVAILABLE=$(echo ${CURRENT_PAYLOAD} | jq .node.fs.inodesFree);
    NODEFS_INODES_CAPACITY=$(echo ${CURRENT_PAYLOAD} | jq .node.fs.inodes);
    # %
    NODEFS_INODES_PERCENTAGE=$(echo "scale=2; ${NODEFS_INODES_AVAILABLE}/${NODEFS_INODES_CAPACITY}*100" | bc);

    # -- 4. Imagefs capacity --
    IMAGEFS_AVAILABLE_BYTES=$(echo ${CURRENT_PAYLOAD} | jq .node.runtime.imageFs.availableBytes);
    IMAGEFS_CAPACITY_BYTES=$(echo ${CURRENT_PAYLOAD} | jq .node.runtime.imageFs.capacityBytes);
    # GB
    IMAGEFS_AVAILABLE_GB=$(echo "scale=2; ${IMAGEFS_AVAILABLE_BYTES}/1024/1024/1024" | bc);
    IMAGEFS_CAPACITY_GB=$(echo "scale=2; ${IMAGEFS_CAPACITY_BYTES}/1024/1024/1024" | bc);
    # %
    IMAGEFS_PERCENTAGE=$(echo "scale=2; ${IMAGEFS_AVAILABLE_GB}/${IMAGEFS_CAPACITY_GB}*100" | bc);

    # -- 5. Imagefs Inodes --
    IMAGEFS_INODES_AVAILABLE=$(echo ${CURRENT_PAYLOAD} | jq .node.fs.inodesFree);
    IMAGEFS_INODES_CAPACITY=$(echo ${CURRENT_PAYLOAD} | jq .node.fs.inodes);
    # %
    IMAGEFS_INODES_PERCENTAGE=$(echo "scale=2; ${NODEFS_INODES_AVAILABLE}/${NODEFS_INODES_CAPACITY}*100" | bc);

    # -- 6. Pid stats --
    #
    PID_MAX=$(echo ${CURRENT_PAYLOAD} | jq .node.rlimit.maxpid);
    PID_CURR=$(echo ${CURRENT_PAYLOAD} | jq .node.rlimit.curproc);
    PID_AVAILABLE=$(echo "scale=2; ${PID_MAX}-${PID_CURR}" | bc);

    # =========
    # Threshold
    # =========
    # Thresholds available differs by K8s distros

    # -- 1. Memory --
    MEMORY_AVAILABLE_MB_THRESHOLD=$(echo ${THRESHOLD_PAYLOAD} | jq '.kubeletconfig.evictionHard."memory.available"' | sed 's/"//g');
    # -- 2. Nodefs capacity --
    NODEFS_AVAILABLE_PERCENTAGE_THRESHOLD=$(echo ${THRESHOLD_PAYLOAD} | jq '.kubeletconfig.evictionHard."nodefs.available"' | sed 's/"//g');
    # -- 3. Nodefs Inodes --
    NODEFS_INODES_AVAILABLE_PERCENTAGE_THRESHOLD=$(echo ${THRESHOLD_PAYLOAD} | jq '.kubeletconfig.evictionHard."nodefs.inodesFree"' | sed 's/"//g');
    # -- 4. Imagefs capacity --
    IMAGEFS_AVAILABLE_PERCENTAGE_THRESHOLD=$(echo ${THRESHOLD_PAYLOAD} | jq '.kubeletconfig.evictionHard."imagefs.available"' | sed 's/"//g');
    # -- 5. Imagefs Inodes --
    IMAGEFS_INODES_AVAILABLE_PERCENTAGE_THRESHOLD=$(echo ${THRESHOLD_PAYLOAD} | jq '.kubeletconfig.evictionHard."imagefs.inodesFree"' | sed 's/"//g');
    # -- 6. Pid stats --
    PID_AVAILABLE_PERCENTAGE_THRESHOLD=$(echo ${THRESHOLD_PAYLOAD} | jq '.kubeletconfig.evictionHard."pid.available"' | sed 's/"//g');

    echo
    echo " ===================================================================== "
    echo " Node ${i}/${NODE_COUNT}: ${NODE}"
    echo " ===================================================================== "
    echo " -- Current State ---------------------------------------------------- "
    echo " --------------------------------------------------------------------- "
    echo "1. memory.available:      ${MEMORY_AVAILABLE_MB}Mi";
    echo "2. nodefs.available:      ${NODEFS_PERCENTAGE}% [${NODEFS_AVAILABLE_GB}/${NODEFS_CAPACITY_GB}Gi]";
    echo "3. nodefs.inodesFree:     ${NODEFS_INODES_PERCENTAGE}% [${NODEFS_INODES_AVAILABLE}/${NODEFS_INODES_CAPACITY}]";
    echo "4. imagefs.available:     ${IMAGEFS_PERCENTAGE}% [${IMAGEFS_AVAILABLE_GB}/${IMAGEFS_CAPACITY_GB}Gi]";
    echo "5. imagefs.inodesFree:    ${IMAGEFS_INODES_PERCENTAGE}% [${IMAGEFS_INODES_AVAILABLE}/${IMAGEFS_INODES_CAPACITY}]";
    echo "6. pid.available:         ${PID_AVAILABLE}";
    echo " --------------------------------------------------------------------- "
    echo " -- Eviction Thresholds ---------------------------------------------- "
    echo " --------------------------------------------------------------------- "
    echo "1. memory.available:      ${MEMORY_AVAILABLE_MB_THRESHOLD}"
    echo "2. nodefs.available:      ${NODEFS_AVAILABLE_PERCENTAGE_THRESHOLD}"
    echo "3. nodefs.inodesFree:     ${NODEFS_INODES_AVAILABLE_PERCENTAGE_THRESHOLD}"
    echo "4. imagefs.available:     ${IMAGEFS_AVAILABLE_PERCENTAGE_THRESHOLD}"
    echo "5. imagefs.inodesFree:    ${IMAGEFS_INODES_AVAILABLE_PERCENTAGE_THRESHOLD}"
    echo "6. pid.available:         ${PID_AVAILABLE_PERCENTAGE_THRESHOLD}"
    echo " --------------------------------------------------------------------- "
    echo
  done
done

Sample payload: