This document is intended for a developer creating new DC/OS CLI subcommands. See also Universe Getting Started.
The DC/OS command-line interface (CLI) is a utility to manage cluster nodes, install and manage packages, inspect the cluster state, and manage services and tasks. The DC/OS CLI is open and extensible: anyone can create a new subcommand and make it available for installation by end users. For example, the Spark DC/OS service provides CLI extensions for working with Spark. When installed, you can type the following command to submit Spark jobs and query their status:
dcos spark [<flags>] <command>
How the DC/OS CLI discovers subcommands
When you run the
dcos command, it searches the current shell’s PATH for executables with names that are prefixed with
dcos- in the
Installing a CLI subcommand
To install a CLI subcommand, run:
dcos package install <package>
dcos package install <package> --cli
The same packaging format and repository is used for both DC/OS services and CLI subcommands.
Creating a DC/OS CLI subcommand
- Executables for Mac, Linux, and Windows
You must assign a standard set of flags to each DC/OS CLI subcommand, described below:
--info --help -h
--info flag shows a short, one-line description of the function of your subcommand. This content is displayed when the user runs
Example from the Spark CLI:
dcos spark --info Spark DC/OS CLI Module
When you run the
dcos command without parameters, the info is returned for each subcommand:
dcos | grep spark spark Spark DC/OS CLI Module
–help and -h
-h flags both show the detailed usage for your subcommand.
Example from the Marathon CLI:
dcos marathon --help Description: Deploy and manage applications to DC/OS. ...
Subcommand naming conventions
The DC/OS CLI subcommand naming convention is:
dcos <subcommand> <resource> <verb>
resource is typically a noun and
verb is an action supported by the resource. For example, in the following command,
app and the action is
dcos marathon app add
The environment variable
DCOS_LOG_LEVEL is set to the log level the user sets at the command line.
The logging levels are described in Python’s logging HOWTO: DEBUG, INFO, WARNING, ERROR and CRITICAL.
Packaging a CLI subcommand
To make your subcommand available to end users:
- Add a package entry to the Mesosphere Universe repository. See the Universe README for the specification.
The package entry must contain a file named resource.json that contains links to the executable subcommands.
When you run
dcos package install <package> --cli:
- The package entry for
is retrieved from the repository.
resource.jsonfile is parsed to find the CLI resources.
- The executable for the user’s platform is downloaded.
The DC/OS CLI module
The DC/OS CLI module has a set of tools useful to subcommand developers.
Example: Hello World subcommand
The Hello World example implements a new subcommand called
dcos package install helloworld --cli dcos helloworld