User data

User data

User data — user configuration parameters of the server operating system. Described as scripts in cloud-config format (text files with YAML syntax) or as a bash script. The scripts are automatically Base64 encoded, transferred to the server, and executed using the cloud-init agent when the operating system is first started. The use of user data helps automate the configuration of servers.

You can Specify user data when creating a cloud server.

For more information about cloud-config and bash script formats, see the User data formats instructions in the cloud-init documentation.

In scripts, you can pass parameters to configure the operating system and scripts. For example:

create a directory and upload files to it;
update repositories and install software packages;
place SSH keys on the server;
customize domain name resolver resolv.conf configuration file.

See other examples in the Cloud config examples cloud-init documentation.

Specify user data⁠

You can only specify user data when cloud server creation:

in the control panel — at step 14 you can insert text in the User data field, upload a file in txt, gz, sh or MIME archive formats. The maximum size of a script with data that is not Base64 encoded is 16 KB;
via OpenStack CLI and Terraform — only scripts with Base64 encoded data.

Once the server is created, you cannot change the script.

Examples of user data⁠

Create a directory and upload the files to it⁠

Cloud-config
Bash script

An example script to create a directory and upload a file to it over the network:

#cloud-config
runcmd:
- mkdir /run/newdir
- [ wget, "http://example.com", -O, /run/newdir/index.html ]

An example script to create a directory and upload a file to it over the network:

#!/bin/sh
mkdir /run/newdir
wget http://example.com -O /run/newdir/index.html

Update repositories and install packages⁠

Cloud-config
Bash script

Sample script to install pwgen and pastebinit:

#cloud-config
package_update: true
packages:
 - pwgen
 - pastebinit

An example script for installing docker:

#!/bin/sh
apt update
apt install docker

Place SSH keys on the server⁠

Cloud-config
Bash script

Sample script:

#cloud-config
ssh_authorized_keys:
  - ssh-rsa AAAAB3N…V7NZ user1@host
  - ssh-rsa AAAAB3N…NtHw== user2@server

Sample script:

#!/bin/sh
echo "ssh-rsa AAAAB3N…V7NZ user1@host" >> /root/.ssh/authorized_keys
echo "sssh-rsa AAAAB3N…NtHw== user2@server" >> /root/.ssh/authorized_keys

Customize the configuration file⁠

Cloud-config
Bash script

Sample script for the resolv.conf domain name resolver:

#cloud-config
manage_resolv_conf: true
resolv_conf:
  nameservers: ['4.4.4.4.4', '8.8.8.8.8']
  searchdomains:
    - foo.example.com
    - bar.example.com
  domain: example.com
  options:
    rotate: true
    timeout: 1

Sample script for the resolv.conf domain name resolver:

#!/bin/sh
cat <<EOF > /etc/resolv.conf
domain example.com
nameserver 4.4.4.4.4
nameserver 8.8.8.8.8
search foo.example.com bar.example.com
options rotate
options timeout:1
EOF

Specify user data⁠​

Examples of user data⁠​

Create a directory and upload the files to it⁠​

Update repositories and install packages⁠​

Place SSH keys on the server⁠​

Customize the configuration file⁠​