mexec-download

#!/usr/bin/env bash

set -euo pipefail

parallel=${PARALLEL-1}
local_dir=.
remote_file=
declare -a kgp_args kcp_args

errecho() {
    >&2 echo "${@//$'\n'/}"
}

display_help() {
	echo "Usage:"
    echo "  kubectl mexec download [-c container_name] [-h] [-p parallel] [--local-directory <local-file>] --remote-path <remote-file-path>"
    echo
    echo "Parameters:"
    echo "  -h,--help              show this help message"
    echo "  -c,--container         specify container name"
    echo "  --retries              set number of retries to complete a copy operation from a container"
    echo "  -p,--parallel          set concurrent processes, default to 1"
    echo "  -d,--local-directory   local file to upload"
    echo "  -r,--remote-path       remote path"
    echo
    echo "Examples:"
    echo "  # Download ./tmp/local-file from every pod with label app.kubernetes.io/name=myapp to pwd with pod name for each pod"
    echo "  kubectl mexec download -l app.kubernetes.io/name=myapp --remote-path /tmp/local-file"
    echo
    echo "  # Download file with concurrent 10 processes in parallel"
    echo "  kubectl mexec download -l app.kubernetes.io/name=myapp --remote-path /tmp/local-file -p 10"
}

parse_arguments() {
    if [[ "$#" = "0" ]]; then
        display_help
        exit 1
    fi

    while :
    do
        if [[ "$#" = "0" ]]; then
            break
        fi

        case "$1" in
        -h|--help)
            display_help
            exit
        ;;
        -p|--parallel)
            parallel=$2
            shift 2
        ;;
        -d|--local-directory)
            local_dir=$2
            shift 2
        ;;
        -r|--remote-path)
            remote_file=$2
            shift 2
        ;;
        -c|--container|--retries)
            kcp_args+=("$1" "$2")
            shift 2
        ;;
        -n|--namespace)
            # pass to both kgp and kubectl exec
            kgp_args+=("$1" "$2")
            kcp_args+=("$1" "$2")
            shift 2
        ;;
        *)
            kgp_args+=("$1")
            shift
        ;;
        esac
    done
}

main() {
    parse_arguments "$@"

    if [[ -z "${remote_file}" ]]; then
        errecho "Error: remote path not provided by --remote-path"
        exit 1
    fi

    if [[ ! -d "${local_dir}" ]]; then
        errecho "Error: '${local_dir}' is not a directory"
    fi

    kubectl get pod "${kgp_args[@]}" -o name | awk -F/ '{print $2}' | xargs -P "${parallel}" -I{} bash -c "kubectl cp ${kcp_args[*]} {}:${remote_file@Q} ${local_dir@Q}/{} |& sed s/^/{}\ /g"
}

main "$@"