Enabling automatic mounting on existing EC2 Linux instances

The /etc/fstab file contains information about file systems. The command mount -a, which runs during instance start-up, mounts all the file systems listed in /etc/fstab. In this procedure, you will manually update the /etc/fstab on an EC2 Linux instance so that the instance uses the EFS mount helper to automatically remount an EFS file system when the instance restarts.

Note

Amazon EFS file systems do not support automatic mounting using /etc/fstab with the EFS mount helper on Amazon EC2 Mac instances running macOS Big Sur or Monterey. Instead, you can use NFS with /etc/fstab to automatically mount your file system on EC2 Mac instances running macOS Big Sur and Monterey.

This method uses the EFS mount helper to mount the file system. The mount helper is part of the amazon-efs-utils set of tools.

The amazon-efs-utils tools are available for installation on Amazon Linux and Amazon Linux 2 Amazon Machine Images (AMIs). For more information about amazon-efs-utils, see Installing the Amazon EFS client. If you are using another Linux distribution, such as Red Hat Enterprise Linux (RHEL), manually build and install amazon-efs-utils. For more information, see Installing the Amazon EFS client on other Linux distributions.

Prerequisites

The following requirements need to be in place before you can successfully implement this procedure:

• You have already created the Amazon EFS file system that you want to be automatically remounted. For more information, see Quick create a file system that has recommended settings (console).

• You have already created the EC2 Linux instance that you want to configure to automatically remount an EFS file system.

• The EFS mount helper is installed on the EC2 Linux instance. For more information, see Installing the Amazon EFS client.

Update the /etc/fstab file

Perform the following steps to update the /etc/fstab on an EC2 Linux instance so that the instance uses the EFS mount helper to automatically remount an EFS file system when the instance restarts.

To update the /etc/fstab file on your EC2 instance

1. Connect to your EC2 instance. For more information, see Connect to your EC2 instance in the Amazon EC2 User Guide.

2. Open the /etc/fstab file in an editor.

3. For automatic mounting using either IAM authorization or an EFS access point:

   • To automatically mount with IAM authorization to an Amazon EC2 instance that has an instance profile, add the following line to the /etc/fstab file.

     file-system-id:/ efs-mount-point efs _netdev,noresvport,tls,iam 0 0

   • To automatically mount with IAM authorization to a Linux instance using a credentials file, add the following line to the /etc/fstab file.

     file-system-id:/ efs-mount-point efs _netdev,noresvport,tls,iam,awsprofile=namedprofile 0 0

   • To automatically mount a file system using an EFS access point, add the following line to the /etc/fstab file.

     file-system-id:/ efs-mount-point efs _netdev,noresvport,tls,iam,accesspoint=access-point-id 0 0

   Warning

   Use the _netdev option, used to identify network file systems, when mounting your file system automatically. If _netdev is missing, your EC2 instance might stop responding. This result is because network file systems need to be initialized after the compute instance starts its networking. For more information, see Automatic mounting fails and the instance is unresponsive.

   For more information, see Mounting with IAM authorization and Mounting with EFS access points.

4. Save the changes to the file.

5. Test the fstab entry by using the mount command with the 'fake' option along with the 'all' and 'verbose' options.

   $ sudo mount -fav
   home/ec2-user/efs      : successfully mounted

Your EC2 instance is now configured to mount the EFS file system whenever it restarts.

Note

In some cases, your Amazon EC2 instance might need to start regardless of the status of your mounted Amazon EFS file system. In such cases, add the nofail option to your file system's entry in your /etc/fstab file.

The line of code you added to the /etc/fstab file does the following.

Field	Description
file-system-id:/	The ID for your Amazon EFS file system. You can get this ID from the console or programmatically from the CLI or an AWS SDK.
efs-mount-point	The mount point for the EFS file system on your EC2 instance.
efs	The type of file system. When you're using the mount helper, this type is always efs.
mount options	Mount options for the file system. This is a comma-separated list of the following options: _netdev – This option tells the operating system that the file system resides on a device that requires network access. This option prevents the instance from mounting the file system until the network has been enabled on the client. noresvport – Tells the NFS client to use a new Transmission Control Protocol (TCP) source port when a network connection is reestablished. Doing this helps make sure that the EFS file system has uninterrupted availability after a network recovery event. tls – Enables encryption of data in transit. iam – Use this option to mount with IAM authorization to an Amazon EC2 that has an instance profile. Using the iam mount option requires also using the tls option. For more information, see Using IAM to control file system data access. awsprofile=namedprofile – Use this option with the iam and tls options to mount with IAM authorization to a Linux instance using a credentials file. For more information about EFS access points, see Using IAM to control file system data access. accesspoint=access-point-id – Use this option with the tls option to mount using an EFS access point. For more information about EFS access points, see Working with Amazon EFS access points.
0	A nonzero value indicates that the file system should be backed up by dump. For EFS, this value should be 0.
0	The order in which fsck checks file systems at boot. For EFS file systems, this value should be 0 to indicate that fsck should not run at start-up.