Parameters in c4

This section describes how configuration parameters in Exasol Deployment Tool (c4) are structured and defined.

Parameter Structure

The c4 deployment tool has a large number of configurable parameters. The majority of these parameters can be left at their default values for most deployment scenarios, and many apply only to a specific deployment platform. Some parameters must however be explicitly set in order to create a deployment. The required parameters for on-prem installation are described in Installation.

You can set configuration values persistently using local configuration files that are loaded when you create the deployment. You can also define configuration values specifically for each deployment by loading a custom configuration file and/or setting parameters on the command line. For more details, see Setting Parameters.

The configuration parameters are organized into modules that indicate in which context they are applied, such as USER or PLAY. Parameter names start with CCC_<MODULE>_ to clearly indicate which context the belong in.

For example:

Parameter Description
CCC_USER_EMAIL Email address to be used for deployment tagging
CCC_PLAY_ACCESS_NODE Boolean for including an access node in the deployment. If this option is unset or set to false an access node will not be deployed.

Get info about parameters

To view all the available parameters in c4, use the command c4 config -F. This command returns a complete list of all parameters and their current values, including parameters that are not relevant for your deployment platform.

To learn more about specific parameters, use c4 config -K <string>, where <string> is the full or partial name of a parameter (case-insensitive).

For example, to get a description of all parameters in the CCC_PLAY module, use c4 config -K ccc_play. To get all parameters that contain “key” in their names, use c4 config -K key.

c4 config -K ccc_play
Found 93 results for query `ccc_play`:

    CCC_PLAY_DIR (string)

      Location of play directories (playgrounds).

      Default value : /home/username/.ccc/play
      Current value : [empty]
      JSON/YAML name: play.dir

    CCC_PLAY_DATADISK_DEFAULT_SIZE (int)

      Default size of the data disk used for play images (in GB).

      Default value : 16
      Current value : [empty]
      JSON/YAML name: play.datadisk_default_size
      
      ...

To learn more about how to use the config command, use c4 config --help.

Setting Parameters

Configuration parameter values can be set in configuration files using shell, JSON, or YAML format. The configuration file config located in the installation directory will be loaded by default. You can also specify a configuration file to be loaded by adding the path to the file on the command line when you create the deployment. Individual parameters can also be set on the command line as environment variables before the command or as command-line options.

Options on the command line can be absolute or relative. An absolute option can be specified anywhere in the command. A relative option must be preceded by the module name. The module name can be followed by multiple (relative) options, see examples below.

When creating a deployment, the parameter values are loaded in the following order of precedence:

  1. User configuration file
  2. Configuration file loaded on the command line
  3. Environment variables
  4. Command-line parameters

For example, a parameter value set in an environment variable will override the value for the same parameter specified in a configuration file, but will be overridden by a value set on the command line.

Parameter Formats

Parameters are formatted differently depending on where they are specified:

Location Format Example
Shell config file Use the full parameter name in UPPERCASE. CCC_PLAY_DATABASE_NAME=my_db
JSON or YAML config file

Exclude the CCC_<MODULE> prefix, use lowercase.

Must be placed in a subsection for the corresponding module.

play:
database_name: my_db
Environment variable Use the full parameter name in UPPERCASE. CCC_PLAY_DATABASE_NAME=my_db
Command-line option (absolute)

Replace _ (underscore) with - (dash), use lowercase.

c4 play --ccc-play-database-name my_db ...
Command-line option (relative)

Exclude the CCC_<MODULE> prefix, replace _ (underscore) with - (dash), use lowercase.

Must be preceded by the module name.

c4 play --database-name my_db --db-password j8IUgef7_IJz9 ...

Parameter Data Types

Each parameter has a defined data type that it accepts for the value. The type is automatically validated when a parameter value is changed. The available types are:

Type Format Example
string Can contain text or numbers. If the string contains spaces, it must be enclosed in quotation marks.

CCC_PLAY_ADMIN_PASSWORD=df0g98j_98Xc

CCC_USER_FULLNAME=”Alice User”

int Number (integer) CCC_PLAY_DB_PORT=8563
bool true or false CCC_PLAY_ACCESS_NODE=true
list

A list of strings.

When specified in environment variables, list values must be entered as space-separated strings. Values that contain spaces must be enclosed in quotation marks.
For example: CCC_MODULE_PARAM='A "B C"'

When defined on the command line, list values must be specified by repeating the parameter name for each element.
For example: --param=A --param='B C' or --param={a,"B C"}

 

Examples