挂载 AWS EBS 卷后运行 Systemd 服务单元

Question

以下是我对解决方案的看法，该解决方案试图满足https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/nvme-ebs-volumes.html#identify-nvme-ebs-device。目前未在生产中使用，但这就是目的……

NVMe 设备名称遵循模式 /dev/nvmen，其中是枚举顺序，对于 EBS，为 1。有时，设备可以在后续实例启动时以不同的顺序响应发现，这会导致设备名称发生变化。

基本思想是Requires=foo.mount通过将 EBS 挂载过程包装在 systemd 中来模仿 systemd 行为。依赖于 EBS 挂载的其他服务可以简单地指定它们必须在挂载可用时service启动。Afterservice

该功能基于将物理设备与卷连接时指定的请求设备进行符号链接的模块构建udev。例如/dev/sdf链接到/dev/nvme...）。请参阅https://github.com/oogali/ebs-automatic-nvme-mapping并参阅上述指南以了解更多详情。

在睡眠循环中等待data-mount.service符号链接出现（允许您有时间连接卷），然后在定义的挂载点挂载卷，并在必要时对其进行格式化。

挂载 EBS 卷的服务

/sbin/ec2-boot-mount-ebs-volume

#!/bin/bash
#
# Copyright 2019 - binx.io B.V.
#
# 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.
#
# Based on https://github.com/binxio/ec2-boot-mount-ebs-volume.
#
# Requires the udev rule that automatically creates a sym-link to the actual device. See the note on udev on https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/nvme-ebs-volumes.html#identify-nvme-ebs-device

set -e -o pipefail
exec 1> >(logger -s -t $(basename $0)) 2>&1

function wait_for_device {
        while [[ ! -b $(readlink -f $1) ]]; do
            echo "waiting for device $1" >&2
            sleep 5;
        done
}

function label_device {
        label=$(blkid $1 | sed -e 's/.*LABEL="\([^"]*\)".*/\1/')
        if [[ -z $label ]]; then
                echo "INFO: labeling $1 with $2">&2
                e2label $1 $2;
        elif [[ $label != $2 ]]; then
                echo "ERROR: device $1 already has label $label, expected $2">&2; exit 1
        fi
}

function main {
        local device mount_point fstype options
        if [[ $# -ne 4 ]] ;then
                echo "Usage: $(basename $0) device-name mount-point fstype options" >&2
                echo "  waits for the volume, formats it if unformatted and mounts it." >&2
                exit 1
        fi
        device="$1"
        mount_point="$2"
        fstype="$3"
        options="$4"

        wait_for_device $device
        real_device=$(readlink -f $device)
        if [[ $real_device != $device ]] ;then
                echo "INFO: $device appeared as $real_device" >&2
        fi

        if grep -q "^$real_device $mount_point " /proc/mounts; then
                echo "INFO: $real_device already mounted on $mount_point" >&2
                return 0
        fi

        if [[ -z $(blkid $real_device) ]] ; then
                echo "INFO: formatting $real_device" >&2
                mkfs -L $mount_point -t $fstype $real_device
        else
                echo "INFO: $real_device already formatted" >&2
                label_device $real_device $mount_point
        fi

        echo "INFO: mounting $real_device on $mount_point" >&2
        mkdir -p $mount_point
        mount -t $fstype -o "$options" $real_device $mount_point
}

main "$@"

/etc/systemd/system/data-mount.service

[Unit]
Description=Mount Data Volume
After=cloud-init-local.service

[Service]
Type=oneshot
RemainAfterExit=yes
# /dev/sdf should be replaced with the device name you requested when attaching the volume
ExecStart=/sbin/ec2-boot-mount-ebs-volume /dev/sdf /mnt/data ext4 "defaults"
ExecStop=umount -v /mnt/data

[Install]

其他服务

/etc/systemd/system/other-service.service.d/override.conf

[Unit]
# if the data-mount.service stops then this service also needs to stop
BindsTo=data-mount.service
# ensure this service starts after the mount is available
After=data-mount.service

Answer 1