nsenter.sh

nsenter.sh

#!/bin/bash

# Function to display usage instructions
usage() {
    echo "Usage: nsenter.sh -n|--namespace <namespace> -p|--pod <pod-name> [-c|--container <container-name>] [-t|--nsenter-namespaces <namespaces>] [-u|--ssh-user <user>] [-h|--ssh-host <host>] [-x|--node-name-prefix <prefix>] -- <command> [args...]"
    echo "Options:"
    echo "  -n, --namespace          Namespace of the pod"
    echo "  -p, --pod                Name of the pod"
    echo "  -c, --container          Name of the container (optional; default is the first container)"
    echo "  -t, --nsenter-namespaces Namespaces for nsenter (optional; overrides defaults, e.g., 'mnt,uts') net namespace is used by deafult"
    echo "  -u, --ssh-user           SSH username (optional)"
    echo "  -h, --ssh-host           SSH host override (optional; default is node name)"
    echo "  -x, --node-name-prefix   Node name prefix (optional)"
    echo "  --                       Command and arguments to execute inside the container"
    echo "Usage example:"
    echo "./nsenter.sh -n d8-virtualization -p cdi-apiserver-7477c5f5c8-xx7r6 -x dev-rnd. tshark -i any -q -z conv,tcp -a duration:10"
    exit 1
}

# Parse named arguments
NAMESPACE=""
POD_NAME=""
CONTAINER_NAME=""
NSENTER_NAMESPACES="" # Optional additional namespaces for nsenter
SSH_USER=""           # Optional SSH username
SSH_HOST_OVERRIDE=""  # Optional SSH host override
NODE_NAME_PREFIX=""   # Optional node name prefix
COMMAND=""

while [[ $# -gt 0 ]]; do
    case "$1" in
        -n|--namespace)
            NAMESPACE="$2"
            shift 2
            ;;
        -p|--pod)
            POD_NAME="$2"
            shift 2
            ;;
        -c|--container)
            CONTAINER_NAME="$2"
            shift 2
            ;;
        -t|--nsenter-namespaces)
            NSENTER_NAMESPACES="$2"
            shift 2
            ;;
        -u|--ssh-user)
            SSH_USER="$2"
            shift 2
            ;;
        -h|--ssh-host)
            SSH_HOST_OVERRIDE="$2"
            shift 2
            ;;
        -x|--node-name-prefix)
            NODE_NAME_PREFIX="$2"
            shift 2
            ;;
        --)
            shift
            COMMAND="$@"
            break
            ;;
        *)
            echo "Unknown option: $1"
            usage
            ;;
    esac
done

# Validate required parameters
if [ -z "$NAMESPACE" ] || [ -z "$POD_NAME" ] || [ -z "$COMMAND" ]; then
    echo "Error: Missing required parameters."
    usage
fi

# If container name is not provided, use the first container in the pod
if [ -z "$CONTAINER_NAME" ]; then
    CONTAINER_INFO=$(kubectl get pod "$POD_NAME" -n "$NAMESPACE" -o jsonpath='{.spec.containers[0].name}')
    if [ -z "$CONTAINER_INFO" ]; then
        echo "Error: Unable to determine the first container in the pod $POD_NAME."
        exit 1
    fi
    CONTAINER_NAME="$CONTAINER_INFO"
fi

# Get pod information
POD_INFO=$(kubectl get pod "$POD_NAME" -n "$NAMESPACE" -o json)
if [ $? -ne 0 ]; then
    echo "Error: Failed to retrieve information about pod $POD_NAME."
    exit 1
fi

# Extract NodeName from pod information
NODE_NAME=$(echo "$POD_INFO" | jq -r '.spec.nodeName')
if [ "$NODE_NAME" == "null" ]; then
    echo "Error: Unable to determine the node for pod $POD_NAME."
    exit 1
fi

# Extract ContainerID from pod information
CONTAINER_ID=$(kubectl get pod "$POD_NAME" -n "$NAMESPACE" -o jsonpath="{.status.containerStatuses[?(@.name=='$CONTAINER_NAME')].containerID}" | sed 's/containerd:\/\/\(.*\)/\1/')
if [ -z "$CONTAINER_ID" ]; then
    echo "Error: Unable to determine the ContainerID for container $CONTAINER_NAME."
    exit 1
fi

# Determine SSH connection details
SSH_HOST=${SSH_HOST_OVERRIDE:-"${NODE_NAME_PREFIX}${NODE_NAME}"} # Use override or default to node name

# Build nsenter command with optional namespaces
NSENTER_CMD="nsenter --target \$(/opt/deckhouse/bin/crictl inspect --output go-template --template '{{.info.pid}}' $CONTAINER_ID)"
# Add namespaces (default or user-provided)
if [ -n "$NSENTER_NAMESPACES" ]; then
    # Use user-provided namespaces (overrides defaults)
    for ns in $(echo "$NSENTER_NAMESPACES" | tr ',' ' '); do
        NSENTER_CMD+=" --$ns"
    done
else
    # Use default namespace (--net)
    NSENTER_CMD+=" --net "
fi

# Connect to the node via SSH and execute the command
if [ -n "$SSH_USER" ]; then
    # Use specified SSH user
    /usr/bin/ssh -t "${SSH_USER}@${SSH_HOST}" "sudo -S bash -c '$NSENTER_CMD $COMMAND'"
else
    # Use SSH without specifying a user
    /usr/bin/ssh -t "${SSH_HOST}" "sudo -S bash -c '$NSENTER_CMD $COMMAND'"
fi

usage.md

./nsenter.sh -n d8-virtualization -p cdi-apiserver-7477c5f5c8-xx7r6 -x dev-rnd. -- tshark -q -z conv,tcp