feat(workflow): support combining fixed strings with variable expansions

[reubenmiller]

Is your feature improvement request related to a problem? Please describe.

The variable expansion supported by the tedge-agent workflow syntax is too restrictive and does not support combining fixed strings with a variable

For example the following script will not be expanded as the tedge-mapper-

script = "sudo systemctl restart tedge-mapper-${.payload.mapperType}"

Because of that, if the user wants to build a script argument by combining a fixed string with a variable reference, they would then need to create a wrapper script which will do the string interpolation.

For example the above would have to be write a wrapper script, e.g. /usr/bin/my_wrapper.sh:

#!/bin/sh
sudo systemctl restart "tedge-mapper-$1"

And then call the wrapper script from the workflow state:

script = "/usr/bin/my_wrapper.sh ${.payload.mapperType}"

Writing a wrapper script adds too much overhead and is harder to maintain as it is easy for the wrapper script to get out of sync with the workflow definition.

Describe the solution you'd like

Support expanding variable references (e.g. ${<dotnotation>}) even when a static prefix/suffix is provided (or even multiple variable references in the same argument?)

operation = "restart_mapper"

[init]
action = "proceed"
on_success = "executing"

[executing]
script = "sudo systemctl restart tedge-mapper-${.payload.mapperType}"
on_success = "successful"

[successful]
action = "cleanup"

[failed]
action = "cleanup"

Describe alternatives you've considered

Additional context

[gligorisaev]

Test Cases:

1. /tests/cumulocity/configuration/configuration_operation.robot

New or Changed Sections

Trigger config_snapshot operation from another operation

• Ensures a configuration snapshot can be triggered as a part of another operation, validating the integration of operations.

Trigger custom config_snapshot operation

• Custom configurations for snapshot operations are tested, ensuring flexibility.

Trigger config_update operation from another workflow

• Similar to config_snapshot, but for update operations, verifying the integration and triggering from other workflows.

Trigger custom config_update operation

• Validates the handling of custom configuration updates.

Customize config operations & Restore config operations

• Ensures custom configurations can be applied and restored correctly, maintaining system integrity.

Customize Operation Workflows

• Tests custom operation workflows, ensuring they work as intended without affecting the main workflows.

The new and changed sections integrate well with the existing suite, ensuring thorough validation of both standard and custom configurations.

2. /tests/cumulocity/log/log_operation.robot

New or Changed Sections

Trigger log_upload operation from another operation

• Ensures a log upload operation can be triggered from another operation.

Trigger custom log_upload operation

• Validates custom log upload operations, checks the retrieved log contents against expected logs.

Customize Operation Workflows

• Customizes operation workflows for ThinEdgeIO, Transfers specific operation workflow files to the device and restarts the service and checks its health status

Restore log_upload operation

• Customizes the log upload operation