Uly.me

cloud engineer

Archives for March 2020

AWS XFS Volume Setup

Here’s how to setup a XFS volume.

file -s /dev/nvme2n1
mkfs -t xfs /dev/nvme2n1

Mount to /data.

mkdir /data
mount /dev/nvme2n1 /data

Add to /etc/fstab.

vim /etc/fstab
#
#
UUID=xxxxxxxxxxxxxxxxxxxxxx /data  xfs  defaults 0 0

Create Swap Disk

To see which disk is available for swap disk use.

lsblk
blkid
df -Th

Format the disk.

fdisk /dev/xvda

Create a swap disk.

sudo mkswap -f /dev/xvda
sudo swapon -s /dev/xvda
# or
sudo swapon /dev/xvda

Check if swap disk is available.

lsblk
free -h 
cat /proc/swaps
cat /proc/meminfo
swapon -s
top
vmstat
vmstat 1 5

GCP Projects List

Here’s how to get a list of GCP projects.

gcloud projects list

Result:

PROJECT_ID            NAME     PROJECT_NUMBER
your-project-id-xxxx  servers  xxxxxxxxxxxx

Use awk to display the project id only.

gcloud projects list | awk '{print $1}'

Result

PROJECT ID
your-project-id-xxxx

GCP Bucket Size

Here are the commands to find out the bucket size in GCP.

gsutil du -s gs://bucket-name/

EBS DeleteOnTermination

Here’s how to set the DeleteOnTermination setting on EBS volumes. The DeleteOnTermination flag determines if an EBS volume will be kept or deleted when an EC2 instance is terminated. The DeleteOnTermination setting can be set during EC2 instance creation, or it can be applied to an existing or a running EC2 instance. The settings can be placed in a JSON file and loaded using –block-device-mappings option upon creation.

During creation.

aws ec2 run-instances \
--count 1 \
--region us-east-2 \
--key-name tfc-ohio \
--image-id ami-xxxxxxxx \
--instance-type t2.large \
--subnet-id subnet-xxxxxxx \
--private-ip-address 10.0.4.100 \
--iam-instance-profile Name=machinerole \
--security-group-ids sg-xxxxxxxxxxxxx \
--block-device-mappings file://mapping.json

Contents of mapping.json

[
  {
    "DeviceName": "/dev/sda1",
    "Ebs": {
      "DeleteOnTermination": true,
      "VolumeSize": 30
      "VolumeType": "gp2"
    }
  }
]

Device name is /dev/sda1. Termination is set to true. Volume size is 30GB and EBS type is gp2.

Modifying an existing EC2 instance.

aws ec2 modify-instance-attribute \
--instance-id i-xxxxxxxxxxxxx \
--block-device-mappings file://mapping.json

Here’s the mapping.json file.

[
  {
    "DeviceName": "/dev/sda1",
    "Ebs": {
      "DeleteOnTermination": false,
    }
  }
]

Obviously, you can’t change Volume size and type to an existing EBS volume, but you can flip the DeleteOnTermination flag and vice versa.

Nmap

Here’s how to list all the devices on your network using nmap.

nmap -sn 192.168.0.0/24

If nmap is not installed, install it.

yum install nmap
apt install nmap

Netstat

Netstat is a utility for gathering network statistics. It comes preinstalled on most systems.

If missing, here’s how to install.

# Redhat, CentOS
yum install net-tools
# Debian, Ubuntu, Mint
apt install net-tools
# SLES, SUSE
zypper install net-tools

Here are some common and useful commands.

# show version
netstat -v
# show routing table
netstat -nr
# show network interface statistics
netstat -ai
# show network connections
netstat -ant
# show network services
netstat -tulpn

List Available PHP Modules

Here’s how to list the available PHP modules.

apt-cache search php- | less

To get details about a module.

apt-cache show php-curl

To install a module.

apt install php-curl

Or install all modules.

apt install php*

Restart Apache after each install.

systemctl restart apache2