The following script is provided to demonstrate how to resize an ebs root volume. The end-to-end solution will launch a demo EC2 instance with an initial 50Gb ebs gp2 root volume, and then resize it to 20Gb.
Note: Please install the jq utility before continuing - Steps 2 & 4 below are dependent on it.
Note: This script is provided to demonstrate how to perform root volume resizing - take extreme care when performing the same actions within a production environment. For extra safety measures - always snapshot any ebs volume BEFORE performing any resizing actions on it.
Pause at 1:36 (original root volume 50Gb)
Filesystem Size Used Avail Use% Mounted on
udev 481M 0 481M 0% /dev
tmpfs 99M 748K 98M 1% /run
/dev/xvda1 49G 1.1G 48G 3% /
tmpfs 492M 0 492M 0% /dev/shm
tmpfs 5.0M 0 5.0M 0% /run/lock
tmpfs 492M 0 492M 0% /sys/fs/cgroup
/dev/loop0 18M 18M 0 100% /snap/amazon-ssm-agent/1480
/dev/loop1 90M 90M 0 100% /snap/core/8268
tmpfs 99M 0 99M 0% /run/user/1000
Pause at 3:52 (resized root volume 20Gb)
Filesystem Size Used Avail Use% Mounted on
udev 481M 0 481M 0% /dev
tmpfs 99M 740K 98M 1% /run
/dev/xvda 20G 1.3G 18G 7% /
tmpfs 492M 0 492M 0% /dev/shm
tmpfs 5.0M 0 5.0M 0% /run/lock
tmpfs 492M 0 492M 0% /sys/fs/cgroup
/dev/loop0 18M 18M 0 100% /snap/amazon-ssm-agent/1480
/dev/loop1 90M 90M 0 100% /snap/core/8268
tmpfs 99M 0 99M 0% /run/user/1000
Defaults to configure the deployment of a demo EC2 instance into the Oregon (REGION) region. The EC2 instance will be configured with the Ubuntu 18.04 OS (IMAGE_ID) installed on a 50Gb (VOLUME_SIZE_LARGE) sized root volume - which will then be cloned and downsized to a 20Gb (VOLUME_SIZE_SMALL) root volume
REGION=us-west-2
AZ=us-west-2c
IMAGE_ID=ami-0d1cd67c26f5fca19 #ubuntu 18.04
USER=ubuntu
VOLUME_SIZE_LARGE=50 #starting size for ebs root volume
VOLUME_SIZE_SMALL=20 #final size after resizing for ebs root volume
You need to update the following environment variables which will be used later to establish a demo EC2 instance with an initial root volume of 50Gb. The demo EC2 instance should be deployed into a subnet with a security group that ensures internet connectivity both in and out.
SSH_KEY_NAME=<ec2 ssh keyname here - example: DemoSSHKey>
SSH_KEY_PATH=<ec2 ssh key path here - example: ~/.ssh/DemoSSHKey.pem>
SUBNET_ID=<subnet id here - where demo ec2 instance is deployed - example: subnet-aa598002>
SECURITY_GROUP_ID=<security group id here - needs to allow inbound ssh connections to the demo ec2 instance - example: >
Launch a demo EC2 instance with a 50Gb root volume with Ubuntu 18.04 installed
CREATE_INSTANCE_RESULT=`aws ec2 run-instances \
--region $REGION \
--image-id $IMAGE_ID\
--count 1 \
--instance-type t2.micro \
--key-name $SSH_KEY_NAME \
--security-group-ids $SECURITY_GROUP_ID \
--subnet-id $SUBNET_ID \
--associate-public-ip-address \
--block-device-mapping "[ { \"DeviceName\": \"/dev/sda1\", \"Ebs\": { \"VolumeSize\": $VOLUME_SIZE_LARGE, \"VolumeType\": \"gp2\" } } ]" \
--tag-specifications "ResourceType=instance,Tags=[{Key=Name,Value=CloudAcademy.EBS.Resizer.Demo}]" "ResourceType=volume,Tags=[{Key=Name,Value=EBSLargeVol}]"`
Outcome:
Retrieve the demo EC2 instance id just launched.
Note: Please install the jq utility before continuing - this step is dependent on it.
INSTANCE_ID=`echo $CREATE_INSTANCE_RESULT | jq -r .Instances[0].InstanceId`
echo INSTANCE_ID=$INSTANCE_ID
Query and display all volumes currently attached to the demo EC2 instance. At the moment there should be just the one 50Gb GP2 root volume attached.
aws ec2 describe-volumes \
--region $REGION \
--filters Name=attachment.instance-id,Values=$INSTANCE_ID
Create a smaller 20Gb (VOLUME_SIZE_SMALL) gp2 volume in the same availabilty zone. Capture the volume id and echo it back out to the console.
Note: Please install the jq utility before continuing - this step is dependent on it.
CREATE_VOL_RESULT=`aws ec2 create-volume \
--region $REGION \
--volume-type gp2 \
--size $VOLUME_SIZE_SMALL \
--availability-zone $AZ \
--tag-specifications 'ResourceType=volume,Tags=[{Key=Name,Value=EBSSmallVol}]'`
NEW_VOL_ID=`echo $CREATE_VOL_RESULT | jq -r .VolumeId`
echo NEW_VOL_ID=$NEW_VOL_ID
Outcome:
Stop the demo EC2 instance in preparation for attaching the new smaller volume.
aws ec2 stop-instances \
--region $REGION \
--instance-ids $INSTANCE_ID
aws ec2 wait instance-stopped \
--region $REGION \
--instance-ids $INSTANCE_ID
Outcome:
Attach the new smaller 20Gb volume to the EC2 demo instance and then restart it. The new volume will be attached to the /dev/xvdf device.
aws ec2 attach-volume \
--region $REGION \
--volume-id $NEW_VOL_ID \
--instance-id $INSTANCE_ID \
--device /dev/xvdf
aws ec2 start-instances \
--region $REGION \
--instance-ids $INSTANCE_ID
aws ec2 wait instance-running \
--region $REGION \
--instance-ids $INSTANCE_ID
Outcome:
Retrieve the auto assigned public IP address and then SSH into the demo EC2 instance and run the commands lsblk and df -h to examine and display the attached devices.
PUBLIC_IP=`aws ec2 describe-instances \
--region $REGION \
--filters \
"Name=instance-state-name,Values=running" \
"Name=instance-id,Values=$INSTANCE_ID" \
--query 'Reservations[*].Instances[*].[PublicIpAddress]' \
--output text`
echo PUBLIC_IP=$PUBLIC_IP
ssh -o "StrictHostKeyChecking no" -v -i $SSH_KEY_PATH $USER@$PUBLIC_IP 'bash -s' <<\EOF
lsblk
echo
df -h
EOF
Output will be something like:
Filesystem Size Used Avail Use% Mounted on
udev 481M 0 481M 0% /dev
tmpfs 99M 748K 98M 1% /run
/dev/xvda1 49G 1.1G 48G 3% /
tmpfs 492M 0 492M 0% /dev/shm
tmpfs 5.0M 0 5.0M 0% /run/lock
tmpfs 492M 0 492M 0% /sys/fs/cgroup
/dev/loop0 18M 18M 0 100% /snap/amazon-ssm-agent/1480
/dev/loop1 90M 90M 0 100% /snap/core/8268
tmpfs 99M 0 99M 0% /run/user/1000
Note: The root volume is 50Gb
💪💪💪
This is where the heavy lifting (resizing) happens!!
The resizing process involves the following sub steps:
- Format the new
/dev/xvdfvolume usingmkfs -t ext4 - Create a new directory
/mnt/new-root-volumeas the mount point for the/dev/xvdfdevice - Rsync all root volume files/folders recursively to the
/mnt/new-root-volumedirectory - Install grub (boot loader) on the new
/mnt/new-root-volumedirectory - Unmount the new
/mnt/new-root-volumedirectory - Copy across both the UUID and Label from the original root volume to the new root volume
ssh -o "StrictHostKeyChecking no" -v -i $SSH_KEY_PATH $USER@$PUBLIC_IP 'bash -s' <<\EOF
echo shrink root vol start...
lsblk
NEW_ROOT_DIR=/mnt/new-root-volume
NEW_DEV=/dev/xvdf
sudo file -s $NEW_DEV
sudo mkfs -t ext4 $NEW_DEV
sudo mkdir $NEW_ROOT_DIR
sudo mount $NEW_DEV $NEW_ROOT_DIR
df -h
echo rsyncing start...
sudo rsync -axv / $NEW_ROOT_DIR/
echo install grub...
sudo grub-install --root-directory=$NEW_ROOT_DIR --force $NEW_DEV
sudo umount $NEW_ROOT_DIR
echo copy uuid across to new root dev...
ROOT_DEV=`sudo blkid -L cloudimg-rootfs`
UUID=`blkid -s UUID -o value $ROOT_DEV`
sudo tune2fs -U $UUID $NEW_DEV
echo copy system label across to new root vol...
LABEL=`sudo e2label $ROOT_DEV`
sudo e2label $NEW_DEV $LABEL
echo shrink root vol finished!!
EOF
Outcome:
Shutdown the demo EC2 instance in preparation for detaching the EBS volumes.
aws ec2 stop-instances \
--region $REGION \
--instance-ids $INSTANCE_ID
aws ec2 wait instance-stopped \
--region $REGION \
--instance-ids $INSTANCE_ID
Outcome:
Detach both EBS volumes, and then reattach the smaller and newer 20Gb ebs gp2 root volume and map it to the root device at /dev/sda1.
for vol in `aws ec2 describe-volumes \
--region $REGION \
--filters Name=attachment.instance-id,Values=$INSTANCE_ID \
--query 'Volumes[*].Attachments[*].VolumeId' --output text`; \
do aws --region us-west-2 ec2 detach-volume --volume-id $vol; \
done
aws ec2 attach-volume \
--region $REGION \
--volume-id $NEW_VOL_ID \
--instance-id $INSTANCE_ID \
--device /dev/sda1
Outcome:
Restart the demo EC2 instance and query and display the updated auto assigned public IP address
aws ec2 start-instances \
--region $REGION \
--instance-ids $INSTANCE_ID
aws ec2 wait instance-running \
--region $REGION \
--instance-ids $INSTANCE_ID
PUBLIC_IP=`aws ec2 describe-instances \
--region $REGION \
--filters \
"Name=instance-state-name,Values=running" \
"Name=instance-id,Values=$INSTANCE_ID" \
--query 'Reservations[*].Instances[*].[PublicIpAddress]' \
--output text`
echo PUBLIC_IP=$PUBLIC_IP
Outcome:
SSH into the demo EC2 instance and run the commands lsblk and df -h to examine and display the attached config of the root device. Compare with the previous values (see previous Step 7).
ssh -o "StrictHostKeyChecking no" -v -i $SSH_KEY_PATH $USER@$PUBLIC_IP 'bash -s' <<\EOF
lsblk
echo
df -h
EOF
Output will be something like:
Filesystem Size Used Avail Use% Mounted on
udev 481M 0 481M 0% /dev
tmpfs 99M 740K 98M 1% /run
/dev/xvda 20G 1.3G 18G 7% /
tmpfs 492M 0 492M 0% /dev/shm
tmpfs 5.0M 0 5.0M 0% /run/lock
tmpfs 492M 0 492M 0% /sys/fs/cgroup
/dev/loop0 18M 18M 0 100% /snap/amazon-ssm-agent/1480
/dev/loop1 90M 90M 0 100% /snap/core/8268
tmpfs 99M 0 99M 0% /run/user/1000
Note: The root volume is now 20Gb
The demo EC2 instance is now operational again - this time with a resized and smaller 20Gb gp2 root ebs volume.
🤘🤘🤘