How to use the command 'nixos-container' (with examples)

The ’nixos-container’ command is used to manage and run NixOS containers using Linux containers. It provides various functionalities to create, start, stop, terminate, and update containers. This article will illustrate each of these use cases with examples.

Use case 1: List running containers

Code:

sudo nixos-container list

Motivation: This use case is helpful to get a list of all the running NixOS containers on the system. It provides an overview of the containers that are currently active.

Explanation:

• ‘sudo’ is used to execute the command with root privileges.
• ’nixos-container’ is the command itself.
• ’list’ is the subcommand used to retrieve the list of running containers.

Example output:

container1
container2
container3

Use case 2: Create a NixOS container with a specific configuration file

Code:

sudo nixos-container create container_name --config-file nix_config_file_path

Motivation: This use case allows you to create a new NixOS container with a specific configuration file. It gives you the flexibility to customize the container’s settings according to your requirements.

Explanation:

• ‘sudo’ is used to execute the command with root privileges.
• ’nixos-container’ is the command itself.
• ‘create’ is the subcommand used to create a new container.
• ‘container_name’ is the name of the container you want to create.
• ‘–config-file’ is an optional argument that specifies the path to the Nix configuration file.

Example:

sudo nixos-container create mycontainer --config-file /etc/nixos/myconfig.nix

Use case 3: Start, stop, terminate, or destroy a specific container

Code:

sudo nixos-container start|stop|terminate|destroy|status container_name

Motivation: This use case enables you to control the lifecycle of a specific NixOS container. You can start, stop, terminate, or even destroy a container as per your requirements.

Explanation:

• ‘sudo’ is used to execute the command with root privileges.
• ’nixos-container’ is the command itself.
• ‘start|stop|terminate|destroy|status’ is the subcommand used to perform different actions on the container.
• ‘container_name’ is the name of the container on which you want to perform the action.

Example:

sudo nixos-container start mycontainer

Use case 4: Run a command in a running container

Code:

sudo nixos-container run container_name -- command command_arguments

Motivation: This use case allows you to execute a specific command inside a running NixOS container. It is useful when you need to run a one-time task or perform some operations within the container’s environment.

Explanation:

• ‘sudo’ is used to execute the command with root privileges.
• ’nixos-container’ is the command itself.
• ‘run’ is the subcommand used to run a command in the container.
• ‘container_name’ is the name of the container in which you want to run the command.
• ‘–’ is used as a separator to indicate the beginning of the command and its arguments.
• ‘command’ is the actual command you want to run inside the container.
• ‘command_arguments’ are the additional arguments or options required by the command.

Example:

sudo nixos-container run mycontainer -- ls -l

Use case 5: Update a container configuration

Code:

sudo $EDITOR /var/lib/container/container_name/etc/nixos/configuration.nix && sudo nixos-container update container_name

Motivation: This use case helps you update the configuration of a specific NixOS container. It allows you to modify the container’s settings, packages, or any other configuration details.

Explanation:

• ‘sudo’ is used to execute the command with root privileges.
• ‘$EDITOR’ is the environment variable that holds the default text editor.
• ‘/var/lib/container/container_name/etc/nixos/configuration.nix’ is the path to the configuration file you want to edit.
• ‘&&’ is a command separator to execute the next command only if the previous one succeeds.
• ‘sudo nixos-container update’ is the command to update the configuration of the container.
• ‘container_name’ is the name of the container you want to update.

Example:

sudo $EDITOR /var/lib/container/mycontainer/etc/nixos/configuration.nix && sudo nixos-container update mycontainer

Use case 6: Enter an interactive shell session on an already-running container

Code:

sudo nixos-container root-login container_name

Motivation: This use case allows you to open an interactive shell session within an already-running NixOS container. It provides direct access to the container’s environment, allowing you to perform tasks or execute commands manually.

Explanation:

• ‘sudo’ is used to execute the command with root privileges.
• ’nixos-container’ is the command itself.
• ‘root-login’ is the subcommand used to enter a shell session.
• ‘container_name’ is the name of the container you want to access.

Example:

sudo nixos-container root-login mycontainer

Conclusion:

The ’nixos-container’ command is a powerful tool for managing and running NixOS containers. It provides various functionalities to create, start, stop, terminate, update containers, and execute commands within them. By understanding and utilizing these different use cases, you can effectively manage and work with NixOS containers in your Linux environment.