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How To Reload Network Configuration with Cloud-Init in Ubuntu 18.04

Ubuntu 5

In this article, we will guide you on how to reload network configuration with Cloud-Init in Ubuntu 18.04. This is an important process that allows you to apply changes made to your network configuration files.

Quick Answer

To reload network configuration with Cloud-Init in Ubuntu 18.04, you need to edit the /etc/netplan/50-cloud-init.yaml file to make the necessary changes, and then run the commands sudo netplan --debug generate and sudo netplan apply to apply the changes. If you need to regenerate the Netplan file from the cloud-init configuration, you can run sudo systemctl restart cloud-init-local.service.

Understanding Cloud-Init and Netplan

Before we dive into the process, it’s important to understand the tools we are using. Cloud-Init is a package that contains utilities for early initialization of a cloud instance. It is the industry standard for multi-distribution, cross-platform cloud instance initialization. It is supported across all major public cloud providers, provisioning systems for private cloud infrastructure, and bare-metal installations.

Netplan on the other hand, is a utility for easily configuring networking on a Linux system. You simply create a YAML description of the required network interfaces and what each should be configured to do. From this description, Netplan will generate all the necessary configuration for your chosen renderer tool.

The configuration file for Netplan resides in the /etc/netplan/ directory and is generated by cloud-init based on the configuration in /etc/cloud/cloud.cfg.d/50-curtin-networking.cfg.

Editing the Netplan Configuration File

To manually configure the network in the new cloud-init/netplan system, you should edit the /etc/netplan/50-cloud-init.yaml file. This file is generated by cloud-init and contains the necessary network configuration details.

Applying Changes in Netplan

Once you have made your changes in the /etc/netplan/50-cloud-init.yaml file, you need to apply these changes. This is done by running the following commands:

sudo netplan --debug generate
sudo netplan apply

The netplan generate command generates the configuration files based on the changes made in /etc/netplan. The --debug option is used to provide extra information that can be useful in debugging.

The netplan apply command applies the changes to the running system. This command does not require a system reboot, so your changes will be applied immediately.

Regenerating the Netplan File

If you make changes in /etc/cloud/cloud.cfg.d, such as modifying the networking configuration, those changes will not automatically generate the Netplan file. The Netplan file is only generated during the initial boot process or when cloud-init is re-run.

To manually trigger the regeneration of the Netplan file from the cloud-init configuration, you can run the following command:

sudo systemctl restart cloud-init-local.service

This command will restart the cloud-init-local.service, which in turn rebuilds the Netplan YAML file from the cloud-init configuration.

Conclusion

In this article, we have covered how to reload network configuration with Cloud-Init in Ubuntu 18.04. We have discussed how to manually configure the network, apply changes in Netplan, and regenerate the Netplan file from the cloud-init configuration.

Remember that any changes made in the network configuration files should be done carefully to avoid network issues. Always make sure to backup your configuration files before making any changes.

If you encounter any issues, you can refer to the official Ubuntu documentation for more information.

What is Cloud-Init?

Cloud-Init is a package that contains utilities for early initialization of a cloud instance. It is used for configuring and customizing cloud instances during the boot process.

What is Netplan?

Netplan is a utility for easily configuring networking on a Linux system. It simplifies network configuration by allowing you to create a YAML description of the required network interfaces.

Where is the Netplan configuration file located?

The Netplan configuration file is located in the /etc/netplan/ directory. The file name is typically 50-cloud-init.yaml.

How do I apply changes made in the Netplan configuration file?

To apply changes made in the Netplan configuration file, you need to run the following commands:

sudo netplan --debug generate
sudo netplan apply

The netplan generate command generates the configuration files based on the changes made, and the netplan apply command applies the changes to the running system.

How can I regenerate the Netplan file from the cloud-init configuration?

To regenerate the Netplan file from the cloud-init configuration, you can run the following command:

sudo systemctl restart cloud-init-local.service

This command restarts the cloud-init-local.service, which rebuilds the Netplan YAML file from the cloud-init configuration.

Do I need to reboot the system after applying changes in Netplan?

No, you do not need to reboot the system after applying changes in Netplan. The changes will be applied immediately without requiring a system reboot.

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