Command, environment and resources

Command and environment

var definition = new ContainerDefinition(ImageSource.FromRegistry("alpine"));
definition.Entrypoint.Add("/bin/sh"); // replaces the entrypoint of the image
definition.Command.AddRange(["-c", "echo started && sleep 3600"]);
definition.Environment.Add("APP_MODE", "test"); // adds or replaces a variable
definition.User = "1000:1000";
definition.WorkingDirectory = "/tmp";
definition.Hostname = "test-server";
definition.Labels.Add("com.example.suite", "integration");

Setting	Effect
Entrypoint	Replaces the entrypoint of the image. Each item is one argument.
Command	The command passed to the entrypoint, one argument per item.
Environment	The environment variables. Add replaces a variable that is already set; GetValue, Contains and Remove read and remove them.
User	The user the container runs as (`name`, `uid` or `uid:gid`).
WorkingDirectory	The working directory inside the container.
Hostname	The hostname of the container.
Labels	Labels added to the container, for your own tools.

Each argument is passed as is, without a shell: to use shell syntax (&&, variables), run a shell as in the example.

The values of the environment variables are passed to the command lines through a file only the current user can read, not on their command line, which every user of the machine can read. wslc is the exception, and so is a value that spans several lines, which stays on the command line.

Resource limits

definition.Resources.MemoryLimit = 512L * 1024 * 1024; // in bytes
definition.Resources.CpuLimit = 1.5; // number of CPUs
definition.Resources.ReadOnlyRootFilesystem = true;

MemoryLimit is in bytes, and CpuLimit is a number of CPUs, which can be fractional.
ReadOnlyRootFilesystem makes the file system of the image read-only. Mount a tmpfs where the service needs to write.

Network

By default, the container uses the default network of the runtime, and you reach it through its published ports. To have containers reach each other by name, connect them to the same network:

definition.Network.Network = "integration-tests"; // a network that already exists
definition.Network.Alias = "database"; // the name the other containers of the network use

To have the library create the network, and to connect a container to several networks, see Networks. Capabilities, shared memory, ulimits and the other less common options are described in Advanced options.

Runtime differences

Apple's container cannot set Hostname. See Container runtimes for the other differences.