path: root/resources/libraries/bash/function/common.sh

# Copyright (c) 2018 Cisco and/or its affiliates.
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at:
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

set -exuo pipefail

# This library defines functions used by multiple entry scripts.
# Keep functions ordered alphabetically, please.

# TODO: Add a link to bash style guide.
# TODO: Consider putting every die into a {} block,
#   the code might become more readable (but longer).


function activate_virtualenv () {

    set -exuo pipefail

    # Arguments:
    # - ${1} - Non-empty path to existing directory for creating virtualenv in.
    # Variables read:
    # - CSIT_DIR - Path to existing root of local CSIT git repository.
    # Variables set:
    # - ENV_DIR - Path to the created virtualenv subdirectory.
    # Variables exported:
    # - PYTHONPATH - CSIT_DIR, as CSIT Python scripts usually need this.
    # Functions called:
    # - die - Print to stderr and exit.

    # TODO: Do we really need to have ENV_DIR available as a global variable?

    if [[ "${1-}" == "" ]]; then
        die "Root location of virtualenv to create is not specified."
    fi
    ENV_DIR="${1}/env"
    rm -rf "${ENV_DIR}" || die "Failed to clean previous virtualenv."

    pip install --upgrade virtualenv || {
        die "Virtualenv package install failed."
    }
    virtualenv "${ENV_DIR}" || {
        die "Virtualenv creation failed."
    }
    set +u
    source "${ENV_DIR}/bin/activate" || die "Virtualenv activation failed."
    set -u
    pip install -r "${CSIT_DIR}/requirements.txt" || {
        die "CSIT requirements installation failed."
    }

    # Most CSIT Python scripts assume PYTHONPATH is set and exported.
    export PYTHONPATH="${CSIT_DIR}" || die "Export failed."
}


function check_download_dir () {

    set -exuo pipefail

    # Fail if there are no files visible in ${DOWNLOAD_DIR}.
    # TODO: Do we need this as a function, if it is (almost) a one-liner?
    #
    # Variables read:
    # - DOWNLOAD_DIR - Path to directory pybot takes the build to test from.
    # Directories read:
    # - ${DOWNLOAD_DIR} - Has to be non-empty to proceed.
    # Functions called:
    # - die - Print to stderr and exit.

    if [[ ! "$(ls -A "${DOWNLOAD_DIR}")" ]]; then
        die "No artifacts downloaded!"
    fi
}


function common_dirs () {

    set -exuo pipefail

    # Variables set:
    # - BASH_FUNCTION_DIR - Path to existing directory this file is located in.
    # - CSIT_DIR - Path to existing root of local CSIT git repository.
    # - TOPOLOGIES_DIR - Path to existing directory with available tpologies.
    # - RESOURCES_DIR - Path to existing CSIT subdirectory "resources".
    # - TOOLS_DIR - Path to existing resources subdirectory "tools".
    # - PYTHON_SCRIPTS_DIR - Path to existing tools subdirectory "scripts".
    # - ARCHIVE_DIR - Path to created CSIT subdirectory "archive".
    # - DOWNLOAD_DIR - Path to created CSIT subdirectory "download_dir".
    # Functions called:
    # - die - Print to stderr and exit.

    BASH_FUNCTION_DIR="$(dirname "$(readlink -e "${BASH_SOURCE[0]}")")" || {
        die "Some error during localizing this source directory."
    }
    # Current working directory could be in a different repo, e.g. VPP.
    pushd "${BASH_FUNCTION_DIR}" || die "Pushd failed"
    CSIT_DIR="$(readlink -e "$(git rev-parse --show-toplevel)")" || {
        die "Readlink or git rev-parse failed."
    }
    popd || die "Popd failed."
    TOPOLOGIES_DIR="$(readlink -e "${CSIT_DIR}/topologies/available")" || {
        die "Readlink failed."
    }
    RESOURCES_DIR="$(readlink -e "${CSIT_DIR}/resources")" || {
        die "Readlink failed."
    }
    TOOLS_DIR="$(readlink -e "${RESOURCES_DIR}/tools")" || {
        die "Readlink failed."
    }
    PYTHON_SCRIPTS_DIR="$(readlink -e "${TOOLS_DIR}/scripts")" || {
        die "Readlink failed."
    }

    ARCHIVE_DIR="$(readlink -f "${CSIT_DIR}/archive")" || {
        die "Readlink failed."
    }
    mkdir -p "${ARCHIVE_DIR}" || die "Mkdir failed."
    DOWNLOAD_DIR="$(readlink -f "${CSIT_DIR}/download_dir")" || {
        die "Readlink failed."
    }
    mkdir -p "${DOWNLOAD_DIR}" || die "Mkdir failed."
}


function compose_pybot_arguments () {

    set -exuo pipefail

    # Variables read:
    # - WORKING_TOPOLOGY - Path to topology yaml file of the reserved testbed.
    # - DUT - CSIT test/ subdirectory, set while processing tags.
    # - TAGS - Array variable holding selected tag boolean expressions.
    # - TOPOLOGIES_TAGS - Tag boolean expression filtering tests for topology.
    # Variables set:
    # - PYBOT_ARGS - String holding part of all arguments for pybot.
    # - EXPANDED_TAGS - Array of strings pybot arguments compiled from tags.

    # No explicit check needed with "set -u".
    PYBOT_ARGS=("--loglevel" "TRACE" "--variable" "TOPOLOGY_PATH:${WORKING_TOPOLOGY}")
    PYBOT_ARGS+=("--suite" "tests.${DUT}.perf")

    EXPANDED_TAGS=()
    for tag in "${TAGS[@]}"; do
        if [[ ${tag} == "!"* ]]; then
            EXPANDED_TAGS+=("--exclude" "${tag#$"!"}")
        else
            EXPANDED_TAGS+=("--include" "${TOPOLOGIES_TAGS}AND${tag}")
        fi
    done
}


function copy_archives () {

    set -exuo pipefail

    # Variables read:
    # - WORKSPACE - Jenkins workspace, copy only if the value is not empty.
    #   Can be unset, then it speeds up manual testing.
    # - ARCHIVE_DIR - Path to directory with content to be copied.
    # Directories updated:
    # - ${WORKSPACE}/archives/ - Created if does not exist.
    #   Content of ${ARCHIVE_DIR}/ is copied here.
    # Functions called:
    # - die - Print to stderr and exit.

    # We will create additional archive if workspace variable is set.
    # This way if script is running in jenkins all will be
    # automatically archived to logs.fd.io.
    if [[ -n "${WORKSPACE-}" ]]; then
        mkdir -p "${WORKSPACE}/archives/" || die "Archives dir create failed."
        cp -r "${ARCHIVE_DIR}"/* "${WORKSPACE}/archives" || die "Copy failed."
    fi
}


function die () {
    # Print the message to standard error end exit with error code specified
    # by the second argument.
    #
    # Hardcoded values:
    # - The default error message.
    # Arguments:
    # - ${1} - The whole error message, be sure to quote. Optional
    # - ${2} - the code to exit with, default: 1.

    set -x
    set +eu
    warn "${1:-Unspecified run-time error occurred!}"
    exit "${2:-1}"
}


function die_on_pybot_error () {

    set -exuo pipefail

    # Source this fragment if you want to abort on any failed test case.
    #
    # Variables read:
    # - PYBOT_EXIT_STATUS - Set by a pybot running fragment.
    # Functions called:
    # - die - Print to stderr and exit.

    if [[ "${PYBOT_EXIT_STATUS}" != "0" ]]; then
        die "${PYBOT_EXIT_STATUS}" "Test failures are present!"
    fi
}


function get_test_code () {

    set -exuo pipefail

    # Arguments:
    # - ${1} - Optional, argument of entry script (or empty as unset).
    #   Test code value to override job name from environment.
    # Variables read:
    # - JOB_NAME - String affecting test selection, default if not argument.
    # Variables set:
    # - TEST_CODE - The test selection string from environment or argument.
    # - NODENESS - Node multiplicity of desired testbed.
    # - FLAVOR - Node flavor string, usually describing the processor.

    TEST_CODE="${1-}" || die "Reading optional argument failed, somehow."
    if [[ -z "${TEST_CODE}" ]]; then
        TEST_CODE="${JOB_NAME-}" || die "Reading job name failed, somehow."
    fi

    case "${TEST_CODE}" in
        *"2n-skx"*)
            NODENESS="2n"
            FLAVOR="skx"
            ;;
        *"3n-skx"*)
            NODENESS="3n"
            FLAVOR="skx"
            ;;
        *)
            # Fallback to 3-node Haswell by default (backward compatibility)
            NODENESS="3n"
            FLAVOR="hsw"
            ;;
    esac
}


function get_test_tag_string () {

    set -exuo pipefail

    # Variables read:
    # - GERRIT_EVENT_TYPE - Event type set by gerrit, can be unset.
    # - GERRIT_EVENT_COMMENT_TEXT - Comment text, read for "comment-added" type.
    # Variables set:
    # - TEST_TAG_STRING - The string following "perftest" in gerrit comment,
    #   or empty.

    # TODO: ci-management scripts no longer need to perform this.

    trigger=""
    if [[ "${GERRIT_EVENT_TYPE-}" == "comment-added" ]]; then
        # On parsing error, ${trigger} stays empty.
        trigger="$(echo "${GERRIT_EVENT_COMMENT_TEXT}" \
            | grep -oE '(perftest$|perftest[[:space:]].+$)')" || true
    fi
    # Set test tags as string.
    TEST_TAG_STRING="${trigger#$"perftest"}"
}


function reserve_testbed () {

    set -exuo pipefail

    # Reserve physical testbed, perform cleanup, register trap to unreserve.
    #
    # Variables read:
    # - TOPOLOGIES - Array of paths to topology yaml to attempt reservation on.
    # - PYTHON_SCRIPTS_DIR - Path to directory holding the reservation script.
    # Variables set:
    # - WORKING_TOPOLOGY - Path to topology yaml file of the reserved testbed.
    # Functions called:
    # - die - Print to stderr and exit.
    # Traps registered:
    # - EXIT - Calls cancel_all for ${WORKING_TOPOLOGY}.

    while true; do
        for topo in "${TOPOLOGIES[@]}"; do
            set +e
            python "${PYTHON_SCRIPTS_DIR}/topo_reservation.py" -t "${topo}"
            result="$?"
            set -e
            if [[ "${result}" == "0" ]]; then
                WORKING_TOPOLOGY="${topo}"
                echo "Reserved: ${WORKING_TOPOLOGY}"
                trap "untrap_and_unreserve_testbed" EXIT || {
                    message="TRAP ATTEMPT AND UNRESERVE FAILED, FIX MANUALLY."
                    untrap_and_unreserve_testbed "${message}" || {
                        die "Teardown should have died, not failed."
                    }
                    die "Trap attempt failed, unreserve succeeded. Aborting."
                }
                python "${PYTHON_SCRIPTS_DIR}/topo_cleanup.py" -t "${topo}" || {
                    die "Testbed cleanup failed."
                }
                break
            fi
        done

        if [[ -n "${WORKING_TOPOLOGY-}" ]]; then
            # Exit the infinite while loop if we made a reservation.
            break
        fi

        # Wait ~3minutes before next try.
        sleep_time="$[ ( $RANDOM % 20 ) + 180 ]s" || {
            die "Sleep time calculation failed."
        }
        echo "Sleeping ${sleep_time}"
        sleep "${sleep_time}" || die "Sleep failed."
    done
}


function run_pybot () {

    set -exuo pipefail

    # Currently, VPP-1361 causes occasional test failures.
    # If real result is more important than time, we can retry few times.
    # TODO: We should be retrying on test case level instead.

    # Arguments:
    # - ${1} - Optional number of pybot invocations to try to avoid failures.
    #   Default: 1.
    # Variables read:
    # - CSIT_DIR - Path to existing root of local CSIT git repository.
    # - ARCHIVE_DIR - Path to store robot result files in.
    # - PYBOT_ARGS, EXPANDED_TAGS - See compose_pybot_arguments.sh
    # Variables set:
    # - PYBOT_EXIT_STATUS - Exit status of most recent pybot invocation.
    # Functions called:
    # - die - Print to stderr and exit.

    # Set ${tries} as an integer variable, to fail on non-numeric input.
    local -i "tries" || die "Setting type of variable failed."
    tries="${1:-1}" || die "Argument evaluation failed."
    all_options=("--outputdir" "${ARCHIVE_DIR}" "${PYBOT_ARGS[@]}")
    all_options+=("${EXPANDED_TAGS[@]}")

    while true; do
        if [[ "${tries}" -le 0 ]]; then
            break
        else
            tries="$((${tries} - 1))"
        fi
        pushd "${CSIT_DIR}" || die "Change directory operation failed."
        set +e
        # TODO: Make robot tests not require "$(pwd)" == "${CSIT_DIR}".
        pybot "${all_options[@]}" "${CSIT_DIR}/tests/"
        PYBOT_EXIT_STATUS="$?"
        set -e
        popd || die "Change directory operation failed."
        if [[ "${PYBOT_EXIT_STATUS}" == "0" ]]; then
            break
        fi
    done
}


function select_tags () {

    set -exuo pipefail

    # Variables read:
    # - WORKING_TOPOLOGY - Path to topology yaml file of the reserved testbed.
    # - TEST_CODE - String affecting test selection, usually jenkins job name.
    # - TEST_TAG_STRING - String selecting tags, from gerrit comment.
    #   Can be unset.
    # - TOPOLOGIES_DIR - Path to existing directory with available tpologies.
    # Variables set:
    # - TAGS - Array of processed tag boolean expressions.

    # NIC SELECTION
    # All topologies NICs
    available=$(grep -hoPR "model: \K.*" "${TOPOLOGIES_DIR}"/* | sort -u)
    # Selected topology NICs
    reserved=$(grep -hoPR "model: \K.*" "${WORKING_TOPOLOGY}" | sort -u)
    # All topologies NICs - Selected topology NICs
    exclude_nics=($(comm -13 <(echo "${reserved}") <(echo "${available}")))

    case "${TEST_CODE}" in
        # Select specific performance tests based on jenkins job type variable.
        *"ndrpdr-weekly"* )
            test_tag_array=("ndrpdrAND64bAND1c"
                            "ndrpdrAND78bAND1c")
            ;;
        *"mrr-daily"* | *"mrr-weekly"* )
            test_tag_array=(# vic
                            "mrrANDnic_cisco-vic-1227AND64b"
                            "mrrANDnic_cisco-vic-1385AND64b"
                            # memif
                            "mrrANDmemifAND64b"
                            "mrrANDmemifANDimix"
                            # crypto
                            "mrrANDipsecAND64b"
                            # ip4 base
                            "mrrANDip4baseAND64b"
                            # ip4 scale FIB 2M
                            "mrrANDip4fwdANDfib_2mAND64b"
                            # ip4 scale FIB 200k
                            "mrrANDip4fwdANDfib_200kANDnic_intel-*710AND64b"
                            # ip4 scale FIB 20k
                            "mrrANDip4fwdANDfib_20kANDnic_intel-*710AND64b"
                            # ip4 scale ACL
                            "mrrANDip4fwdANDacl1AND10k_flowsAND64b"
                            "mrrANDip4fwdANDacl50AND10k_flowsAND64b"
                            # ip4 scale NAT44
                            "mrrANDip4fwdANDnat44ANDbaseAND64b"
                            "mrrANDip4fwdANDnat44ANDsrc_user_4000AND64b"
                            # ip4 features
                            "mrrANDip4fwdANDfeatureANDnic_intel-*710AND64b"
                            # ip4 tunnels
                            "mrrANDip4fwdANDencapANDip6unrlayANDip4ovrlayANDnic_intel-x520-da2AND64b"
                            "mrrANDip4fwdANDencapANDnic_intel-*710AND64b"
                            "mrrANDl2ovrlayANDencapANDnic_intel-*710AND64b"
                            # ip6 base
                            "mrrANDip6baseANDethAND78b"
                            # ip6 features
                            "mrrANDip6fwdANDfeatureANDnic_intel-*710AND78b"
                            # ip6 scale FIB 2M
                            "mrrANDip6fwdANDfib_2mANDnic_intel-*710AND78b"
                            # ip6 scale FIB 200k
                            "mrrANDip6fwdANDfib_200kANDnic_intel-*710AND78b"
                            # ip6 scale FIB 20k
                            "mrrANDip6fwdANDfib_20kANDnic_intel-*710AND78b"
                            # ip6 tunnels
                            "mrrANDip6fwdANDencapANDnic_intel-x520-da2AND78b"
                            # l2xc base
                            "mrrANDl2xcfwdANDbaseAND64b"
                            # l2xc scale ACL
                            "mrrANDl2xcANDacl1AND10k_flowsAND64b"
                            "mrrANDl2xcANDacl50AND10k_flowsAND64b"
                            # l2xc scale FIB 2M
                            "mrrANDl2xcANDfib_2mAND64b"
                            # l2xc scale FIB 200k
                            "mrrANDl2xcANDfib_200kANDnic_intel-*710AND64b"
                            # l2xc scale FIB 20k
                            "mrrANDl2xcANDfib_20kANDnic_intel-*710AND64b"
                            # l2bd base
                            "mrrANDl2bdmaclrnANDbaseAND64b"
                            # l2bd scale ACL
                            "mrrANDl2bdmaclrnANDacl1AND10k_flowsAND64b"
                            "mrrANDl2bdmaclrnANDacl50AND10k_flowsAND64b"
                            # l2bd scale FIB 2M
                            "mrrANDl2bdmaclrnANDfib_2mAND64b"
                            # l2bd scale FIB 200k
                            "mrrANDl2bdmaclrnANDfib_200kANDnic_intel-*710AND64b"
                            # l2bd scale FIB 20k
                            "mrrANDl2bdmaclrnANDfib_20kANDnic_intel-*710AND64b"
                            # l2 patch base
                            "mrrANDl2patchAND64b"
                            # srv6
                            "mrrANDsrv6ANDnic_intel-x520-da2AND78b"
                            # vts
                            "mrrANDvtsANDnic_intel-x520-da2AND114b"
                            # vm vhost l2xc base
                            "mrrANDvhostANDl2xcfwdANDbaseAND64b"
                            "mrrANDvhostANDl2xcfwdANDbaseANDimix"
                            # vm vhost l2bd base
                            "mrrANDvhostANDl2bdmaclrnANDbaseAND64b"
                            "mrrANDvhostANDl2bdmaclrnANDbaseANDimix"
                            # vm vhost ip4 base
                            "mrrANDvhostANDip4baseAND64b"
                            "mrrANDvhostANDip4baseANDimix"
                            # Exclude
                            "!vhost_256ANDnic_intel-x520-da2"
                            "!vhostANDnic_intel-xl710"
                            "!cfs_opt"
                            "!lbond_dpdk")
            ;;
        * )
            if [[ -z "${TEST_TAG_STRING-}" ]]; then
                # If nothing is specified, we will run pre-selected tests by
                # following tags.
                test_tag_array=("mrrANDnic_intel-x710AND1cAND64bANDip4base"
                                "mrrANDnic_intel-x710AND1cAND78bANDip6base"
                                "mrrANDnic_intel-x710AND1cAND64bANDl2bdbase"
                                "mrrANDnic_intel-x710AND1cAND64bANDl2xcbase"
                                "!dot1q")
            else
                # If trigger contains tags, split them into array.
                test_tag_array=(${TEST_TAG_STRING//:/ })
            fi
            ;;
    esac

    # Blacklisting certain tags per topology.
    case "${TEST_CODE}" in
        *"3n-hsw"*)
            test_tag_array+=("!drv_avf")
            ;;
        *"2n-skx"*)
            test_tag_array+=("!ipsechw")
            ;;
        *"3n-skx"*)
            test_tag_array+=("!ipsechw")
            ;;
        *)
            # Default to 3n-hsw due to compatibility.
            test_tag_array+=("!drv_avf")
            ;;
    esac

    # We will add excluded NICs.
    test_tag_array+=("${exclude_nics[@]/#/!NIC_}")

    TAGS=()

    # We will prefix with perftest to prevent running other tests
    # (e.g. Functional).
    prefix="perftestAND"
    if [[ "${TEST_CODE}" == "vpp-"* ]]; then
        # Automatic prefixing for VPP jobs to limit the NIC used and
        # traffic evaluation to MRR.
        prefix="${prefix}mrrANDnic_intel-x710AND"
    fi
    for tag in "${test_tag_array[@]}"; do
        if [[ ${tag} == "!"* ]]; then
            # Exclude tags are not prefixed.
            TAGS+=("${tag}")
        else
            TAGS+=("${prefix}${tag}")
        fi
    done
}


function select_topology () {

    set -exuo pipefail

    # Variables read:
    # - NODENESS - Node multiplicity of testbed, either "2n" or "3n".
    # - FLAVOR - Node flavor string, currently either "hsw" or "skx".
    # - CSIT_DIR - Path to existing root of local CSIT git repository.
    # - TOPOLOGIES_DIR - Path to existing directory with available tpologies.
    # Variables set:
    # - TOPOLOGIES - Array of paths to suitable topology yaml files.
    # - TOPOLOGIES_TAGS - Tag expression selecting tests for the topology.
    # Functions called:
    # - die - Print to stderr and exit.

    case_text="${NODENESS}_${FLAVOR}"
    case "${case_text}" in
        "3n_hsw")
            TOPOLOGIES=(
                        "${TOPOLOGIES_DIR}/lf_3n_hsw_testbed1.yaml"
                        "${TOPOLOGIES_DIR}/lf_3n_hsw_testbed2.yaml"
                        "${TOPOLOGIES_DIR}/lf_3n_hsw_testbed3.yaml"
                       )
            TOPOLOGIES_TAGS="3_node_single_link_topo"
            ;;
        "2n_skx")
            TOPOLOGIES=(
                        "${TOPOLOGIES_DIR}/lf_2n_skx_testbed21.yaml"
                        #"${TOPOLOGIES_DIR}/lf_2n_skx_testbed22.yaml"
                        #"${TOPOLOGIES_DIR}/lf_2n_skx_testbed23.yaml"
                        "${TOPOLOGIES_DIR}/lf_2n_skx_testbed24.yaml"
                       )
            TOPOLOGIES_TAGS="2_node_*_link_topo"
            ;;
        "3n_skx")
            TOPOLOGIES=(
                        "${TOPOLOGIES_DIR}/lf_3n_skx_testbed31.yaml"
                        "${TOPOLOGIES_DIR}/lf_3n_skx_testbed32.yaml"
                       )
            TOPOLOGIES_TAGS="3_node_*_link_topo"
            ;;
        *)
            # No falling back to 3n_hsw default, that should have been done
            # by the function which has set NODENESS and FLAVOR.
            die "Unknown specification: ${case_text}"
    esac

    if [[ -z "${TOPOLOGIES-}" ]]; then
        die "No applicable topology found!"
    fi
}


function untrap_and_unreserve_testbed () {
    # Use this as a trap function to ensure testbed does not remain reserved.
    # Perhaps call directly before script exit, to free testbed for other jobs.
    # This function is smart enough to avoid multiple unreservations (so safe).
    # Topo cleanup is executed (call it best practice), ignoring failures.
    #
    # Hardcoded values:
    # - default message to die with if testbed might remain reserved.
    # Arguments:
    # - ${1} - Message to die with if unreservation fails. Default hardcoded.
    # Variables read (by inner function):
    # - WORKING_TOPOLOGY - Path to topology yaml file of the reserved testbed.
    # - PYTHON_SCRIPTS_DIR - Path to directory holding Python scripts.
    # Variables written:
    # - WORKING_TOPOLOGY - Set to empty string on successful unreservation.
    # Trap unregistered:
    # - EXIT - Failure to untrap is reported, but ignored otherwise.
    # Functions called:
    # - die - Print to stderr and exit.

    set -xo pipefail
    set +eu  # We do not want to exit early in a "teardown" function.
    trap - EXIT || echo "Trap deactivation failed, continuing anyway."
    wt="${WORKING_TOPOLOGY}"  # Just to avoid too long lines.
    if [[ -z "${wt-}" ]]; then
        set -eu
        echo "Testbed looks unreserved already. Trap removal failed before?"
    else
        python "${PYTHON_SCRIPTS_DIR}/topo_cleanup.py" -t "${wt}" || true
        python "${PYTHON_SCRIPTS_DIR}/topo_reservation.py" -c -t "${wt}" || {
            die "${1:-FAILED TO UNRESERVE, FIX MANUALLY.}" 2
        }
        WORKING_TOPOLOGY=""
        set -eu
    fi
}


function warn () {
    # Print the message to standard error.
    #
    # Arguments:
    # - ${@} - The text of the message.

    echo "$@" >&2
}