Uly.me

cloud engineer

Display Instance ID & IP Address

How to display IP address and Instance ID on web page behind a AWS load balancer.

Add these 2 commands in crontab. The job runs every 5 mins.

*/5 * * * * /usr/bin/curl http://169.254.169.254/latest/meta-data/instance-id > /var/www/html/id.txt
*/5 * * * * /usr/bin/curl http://169.254.169.254/latest/meta-data/public-ipv4 > /var/www/html/ip.txt

You can view on the site.

# your domain
http://yourdomain.com/ip.txt
http://yourdomain.com/id.txt
# your server ip address
http://1.1.1.1/ip.txt
http://1.1.1.1/id.txt

Sudo With No Password

If you’re the only user on your system, you don’t need to be prompted every time you run the sudo command. Add yourself to the sudoers file.

# create a new file
sudo visudo -f /etc/sudoers.d/users

Add this line.

# add your username
username ALL=(ALL) NOPASSWD:ALL

Exit and try again.

# exit out and login again
exit
# try to sudo again
sudo -i
# there's no password prompt for sudo this time

Apache & Webroot

Where’s Apache and webroot for the different distros?

Webroot:

# Redhat, Fedora, Centos, Amazon Linux
/var/www/html
# Debian, Ubuntu, Mint
/var/www/html

Apache Configuration:

# Redhat, Fedora, Centos, Amazon Linux
/etc/httpd/conf/httpd.conf
# Debian, Ubuntu, Mint
/etc/apache2/sites-available/default

Icecast on Docker

Run Icecast2 on a Docker container.

docker run -d \
-p 8000:8000 \
-e ICECAST_SOURCE_PASSWORD=aaaa \
-e ICECAST_ADMIN_PASSWORD=bbbb \
-e ICECAST_PASSWORD=cccc \
-e ICECAST_RELAY_PASSWORD=dddd \
moul/icecast

Access localhost:8000 on browser. Github.