Motivation

Ignite 3 CLI tool is a command-line utility that acts as an entry point for all monitoring and management operations with Apache Ignite clusters. A user should download the tool from the website and then use it to:

• Connect to a cluster to monitor its state and perform management operations (configuration changes, cluster init).
• Connect to a cluster to run SQL queries.
• Connect to a cluster to get the cluster status (topology, version).

Description

The tool should be designed and developed with an explicit focus on usability and respect for https://clig.dev/#guidelines. In addition to regular commands, it should feature a fully-fledged REPL for different functions. REPL mode must provide the following capabilities:

• Advanced command autocompletion: not only static commands but dynamic completion for parameters and values; in sql mode keywords and dynamic table schema are supported.
• Command history.
• Current status.

REPL mode is used by default and is activated if the ignite command is executed without parameters.

Communication with the cluster 

The tool should connect to a remote cluster via REST endpoints provided by the cluster.  For SQL REPL mode the JDBC is used.

Benefits of using REST as a communication realization between CLI and Ignite 3 cluster:

• This approach seems to be the de-facto standard for the client-server communication model.
• CLI can connect to any cluster it has a network connection to.
• REST component already implemented in Ignite 3.
• REST client can be generated from Open API specification (see IEP-87).

Error handling

If a user makes a mistake in syntax, an appropriate error message should be shown. It must describe what exactly is wrong. Possible options: unknown command, unknown parameter, missing mandatory parameter, etc.

In non-REPL mode, if a user attempts to execute a command that is only available in REPL, the tool should suggest using the REPL mode.

Errors and messing should be sent into stderr. The output of commands should be sent to stdout.

Parameters

Generally (exclusions are defined on a case-by-case basis), every parameter for every command should have two name aliases: a long version starting with two dashes (e.g., --cluster-url), and an optional short single-character version starting with a single dash (e.g., -c).

The long version name can be separated from the value by either a space or by ‘=’:

•  --cluster-url localhost:8080
•  --cluster-url=localhost:8080

The short version name can be separated from the value only by a space:

• -c localhost:8080

Options without a value (i.e. on-off switches) are allowed. If several such options in a single command are provided using their short names, they can be collapsed. For example, ignite -a -b -c is equivalent to ignite -abc.

Configuration

CLI tool should have configurable defaults. They could be placed in the config file and modified by the user. Also, a special command can be used to set the default value. For example:

ignite cli config set cluster-url=http://localhost:3344

There should an option to use a custom configuration file that is put on CLI run:

ignite topology --cli-config=./.config/path

Exit codes

Exit codes have to be mapped with Ignite 3 error codes.

Quick overview of existing CLIs

Ksql CLI

KsqlDB can be queried from Ksql CLI https://docs.ksqldb.io/en/latest/operate-and-deploy/installation/cli-config/.

• written in Java
• uses REST as a communication protocol
• has interactive and non-interactive modes
• does not support autocompletion

Hazelcast CLI (beta)

https://github.com/hazelcast/hazelcast-commandline-client

• written in go
• uses REST as a communication protocol (hazelcast ships go client)
• supports interactive and non-interactive modes
• has advanced autocompletion in interactive mode
• has custom keyboard shortcuts to navigate in interactive mode
• supports bash autocomplete for non-interactive mode

Snowsql

https://docs.snowflake.com/en/user-guide/snowsql-use.html

• supports scripts execution
• does not support featured non-interactive mode
• has a reach interactive interface
• supports custom commands in interactive mode like "!print", "!define".
• has advanced SQL autocompletion

Command list

help

Help must be available for every command and should include at least the following:

• Description of the command (what it does and when it should be used).
• The general syntax of the command.
• List of available parameters with their names and descriptions.
• Typical usage examples for the command in general, and for specific parameters where appropriate.

REPL mode

non-REPL mode

clear

This is a REPL-only command.

exit

Stop current interactive session. This is a REPL-only command.

bootstrap

Bootstraps the ignite workspace in the local machine. This is the analog is the equivalent ignite init command from the previous cli version.

REPL mode

non-REPL mode