Ubuntu – How to mount /tmp in /mnt on EC2

amazon ec2fstabUbuntuubuntu-12.04

I was wondering what is the best way to mount the /tmp endpoint in the ephemeral storage /mnt on an EC2 instance and give the ubuntu user default write permissions.

Some suggest editing /etc/rc.local this way:

mkdir -p /mnt/tmp && mount --bind -o nobootwait /mnt/tmp /tmp

However that doesn't work for me (files differs).

I tried editing the default fstab entry:

/dev/xvdb /mnt auto defaults,nobootwait,comment=cloudconfig 0 2

replacing /mnt with /tmp and and giving it a umask=0777, however it doesn't work because of cloudconfig.

I'm using Ubuntu 12.04. Thanks.

Best Answer

There are a couple problems with the initial suggestion you list, though it seems like it's headed in a good direction:

For security purposes, the mkdir command should create the directory with the sticky bit set in the mode:
```
mkdir -m 1777 /mnt/tmp
```
The -o nobootwait doesn't seem necessary as this is not being saved in /mnt/fstab.

So, I'd recommend trying this in /etc/rc.local:

test -d /mnt/tmp || mkdir -m 1777 /mnt/tmp
mount --bind /mnt/tmp /tmp

Any attempt to put the bind mount in /etc/fstab is going to run into problems when you stop/start the instance or when you create an AMI and run a new instance as /mnt is ephemeral storage and all contents (including the /mnt/tmp directory) are going to disappear.

Related Solutions

Ubuntu – How to get USB Devices to AutoMount in Ubuntu 12.04 Server

From the Ubuntu documentation, try installing usbmount.

sudo apt-get install usbmount

Here is the description from the repo:

automatically mount and unmount USB mass storage devices This package automatically mounts USB mass storage devices (typically USB pens) when they are plugged in, and unmounts them when they are removed. The mountpoints (/media/usb[0-7] by default), filesystem types to consider, and mount options are configurable. When multiple devices are plugged in, the first available mountpoint is automatically selected. If the device provides a model name, a symbolic link /var/run/usbmount/MODELNAME pointing to the mountpoint is automatically created.

When using automount, it will mount the storage devices at /media/usb[0-7] (there is no dialog).

Printers/scanners are not "mounted" and would be configured differently. Although, if your end goal is to just pass these along to your Windows guest, you need to install the VirtualBox Extension Pack, from here https://www.virtualbox.org/wiki/Downloads. The devices to not need to be set up within your Ubuntu host prior to using them with your Windows guest.

Ubuntu – Move /var directories to to /mnt on an EC2 instance

I don't know what you keep in /var/www, but the contents on my servers definitely can't be described as "ephemeral", which I understand to mean "could go away any time, and I don't much mind". If that's not what amazon means by "ephemeral", I apologise.

As for /var/log, if you don't care about the log data at all, don't collect it in the first place.

If you do care about it, but can't afford to hold it in primary storage very long, then this isn't a mounting issue so much as a log management problem. I'd be inclined to use logrotate, if it's available to you, and configure it to move old logs out to /mnt every week or so. That way, the old logs are there (until the ephemeral storage goes away), but the current log is safe on primary storage.

A logrotate recipe like

/var/log/foo {
    olddir /mnt
    compress
    weekly
    rotate 1000
    postrotate
    /etc/rc.d/init.d/fooservice restart
    endscript
}

might be of use, at least as a template.

Best Answer

Related Solutions

Ubuntu – How to get USB Devices to AutoMount in Ubuntu 12.04 Server

Ubuntu – Move /var directories to to /mnt on an EC2 instance

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