rsync over kubectl

kubectl-rsync

#! /bin/bash
# This script is inspired by following scripts:
# * https://serverfault.com/a/887402
# * https://github.com/dmrub/kube-utils/blob/master/kube-rsync

set -euo pipefail

: "${KUBECTL_RSYNC_RSH:=}"
: "${KUBE_CONTEXT:=}"
: "${POD_NAMESPACE:=}"
: "${POD_NAME:=}"
: "${REMOTE_BIN_PATH:=/usr/bin/rsync}"

if [[ -z "$KUBECTL_RSYNC_RSH" ]]; then
    [[ -n "$KUBE_CONTEXT" ]] && echo >&2 "* Found \$KUBE_CONTEXT = $KUBE_CONTEXT"
    [[ -n "$POD_NAMESPACE" ]] && echo >&2 "* Found \$POD_NAMESPACE = $POD_NAMESPACE"
    [[ -n "$POD_NAME" ]] && echo >&2 "* Found \$POD_NAME = $POD_NAME"
    [[ -n "$REMOTE_BIN_PATH" ]] && echo >&2 "* Found \$REMOTE_BIN_PATH = $REMOTE_BIN_PATH"

    while [[ $# -gt 0 ]]; do
        case "$1" in
        --context)
            KUBE_CONTEXT="$2"
            shift 2
            ;;
        --context=*)
            KUBE_CONTEXT="${1#*=}"
            shift
            ;;
        -c | --container)
            POD_CONTAINER="$2"
            shift 2
            ;;
        --container=*)
            POD_CONTAINER="${1#*=}"
            shift
            ;;
        -n | --namespace)
            POD_NAMESPACE="$2"
            shift 2
            ;;
        --namespace=*)
            POD_NAMESPACE="${1#*=}"
            shift
            ;;
        -p | --path)
            REMOTE_BIN_PATH="$2"
            shift 2
            ;;
        --path=*)
            REMOTE_BIN_PATH="${1#*=}"
            shift
            ;;
        -h | --help)
            echo "Rsync file and directories from/to Kubernetes pod"
            echo ""
            echo "IMPORTANT:"
            echo "'rsync' must be installed on both the local machine and the target container for this script to work."
            echo ""
            echo "Usage:"
            echo "  $(basename "$0") [options] [--] [rsync-options] SRC DST"
            echo ""
            echo "Options:"
            echo "  -p, --path=''              Set path to rsync on a remote side, by default /usr/bin/rsync"
            echo "  -n, --namespace=''         Namespace of the pod"
            echo "      --context=''           The name of the kubeconfig context to use."
            echo "                             Has precedence over KUBE_CONTEXT variable."
            echo "  -c, --container=''         Container name. If omitted, the first container in the pod will be chosen"
            echo "      --help                 Display this help and exit"
            echo ""

            exit
            ;;
        --)
            shift
            break
            ;;
        *)
            break
            ;;
        esac
    done

    export KUBECTL_RSYNC_RSH=1
    export KUBE_CONTEXT POD_NAMESPACE POD_CONTAINER REMOTE_BIN_PATH

    exec rsync --rsync-path="$REMOTE_BIN_PATH" --blocking-io --rsh="$0" "$@"
fi

# Running under --rsh

# If user uses pod@namespace, rsync passes args as `-l pod namespace`
if [[ x"$1" == x"-l" ]]; then
    POD_NAME="$2"
    POD_NAMESPACE="$3"
    shift 3
else
    POD_NAMESPACE="$POD_NAMESPACE"
    POD_NAME="$1"
    shift
fi

export KUBE_CONTEXT POD_NAMESPACE POD_CONTAINER POD_NAME
echo >&2 "* Connect to pod $POD_NAME in ${POD_NAMESPACE:-current namespace}"

exec kubectl exec \
    -i \
    ${KUBE_CONTEXT:+--context=${KUBE_CONTEXT}} \
    ${POD_NAMESPACE:+--namespace=${POD_NAMESPACE}} \
    ${POD_CONTAINER:+--container=${POD_CONTAINER}} \
    "${POD_NAME}" \
    -- \
    "$@"

exec rsync --rsync-path=/usr/bin/rsync --blocking-io --rsh="$0" "$@"