Below are a few advanced use cases in which you configure values using configurable variables.
Configure in multiple modules
The configurable variables can be defined in different modules. Therefore, it is necessary to provide the information of the module in which the variable is defined.
The module information requirement can be explained in the following table according to the variable definition.
| Place where the variable is defined | Module information | ||
|---|---|---|---|
| Package | Module | Organization name | Module Name |
| Root package | Root module | optional | optional |
| Root package | Non-root module | optional | mandatory |
| Non-root package | Root/ Non-root module | mandatory | mandatory |
Note: The module information is not needed for configuring single
balfile execution.
The format of providing module information in each configuration syntax is described below.
Command-line argument syntax
The key of a CLI parameter can be specified as,
-Ckey=value
The key can contain module information as follows.
key:= [[org-name .] module-name .] variable
TOML syntax
The following format is used to provide the module information of a variable in the TOML based configuration.
[org-name.module-name] variable-name = "value"
Environment variable syntax
The key of an environment variable can be specified as,
BAL_CONFIG_VAR_key=value
The key can contain module information as follows.
key:= ORGNAME_MODULENAME_VARIABLE
Each part in the structured identifier of the key is converted to uppercase, and the dots are converted to underscores.
Configure in a Kubernetes environment
In the Kubernetes environment, a pod can use the configuration TOML file that contains the configuration values in the following ways.
- as files in a data volume that is mounted on one or more of its containers
- as environment variables for the containers
Configure sensitive values
Configuration values containing passwords or secrets should not be passed with the normal configuration.
Such sensitive data can be passed to runtime using a different TOML file, and we can prioritize it higher than the
normal configuration by prefixing the file path in the BAL_CONFIG_FILES environment variable.
The configuration of sensitive data can be handled at the deployment of the Ballerina program.
In a Kubernetes environment, a Kubernetes secret can be used to inject sensitive data into the containers. The TOML file that contains the sensitive data can be stored as a secret resource in Kubernetes and can be placed in a volume mount when running a pod. The file path can be specified via an environment variable as above.