How to write your own tapa¶

A good way to start creating your tapa is to generate template with special tapa:

tapas tapa

Link to repository is here.

Tapa structure¶

Tapa consists of following parts:

• template directory
• tapa.py file

Jinja¶

Tapas uses jinja2 template engine. Almost everything in template directory can be template. You can substitute values into directory names, file names and file content.

tapa.py structure¶

Tapas reads two functions from tapa.py file:

• get_params
• post_init

Both functions and even tapa.py file are optional.

Project generation lifecycle¶

Project generation lifecycle consists of 5 steps:

1. Read tapa.py file.
2. Collect project params from get_params function if present.
3. Ask for params from user to build environment or load them from --param argument.
4. Generate files with template directory.
5. Call post_init function if present.
6. Call tapas system actions (e.g. generating license, init git repository etc.).

get_params function¶

get_params function must return list of parameter descriptions.

Setup example:

from tapas.params import StrParameter


def get_params():
    return [
        StrParameter("directory_name"),
        StrParameter("file_name"),
        StrParameter("value_in_file"),
    ]

Output example:

su0@tower:~$ tapas test-tapa
Enter directory_name value: abc
Enter file_name value: def
Enter value_in_file value: jkl

Redefine prompt string¶

You can define your own prompt string with prompt parameter:

from tapas.params import StrParameter


def get_params():
    return [
        StrParameter("param.id", prompt="Please enter parameter value"),
    ]

Output example:

su0@tower:~$ tapas test-tapa
Please enter parameter value: jkl

Default value¶

You can set default value with default_value parameter:

from tapas.tools import prompt


def ask():
    prompt('directory_name', prompt_string='What is directory name?', default_value='some-default-value')
    prompt('file_name', default_value='default-file-name')
    prompt('value_in_file')

Output example:

su0@tower:~$ tapas test-tapa
What is directory name? dir-name
Enter file_name value [default-file-name]: 
Enter value_in_file value: jkl

Default value will be used in case of empty user input.

Tapas system params¶

Tapas has some special parameters to pass into returning environment. Those parameters can configure prompt and actions for many common cases like license file generation or git repo init.

Adding license file¶

Tapas uses uses lice to generate license file. To add license generation prompt add TAPAS_SYSTEM_LICENSE_PARAMETER to get_params function:

from tapas.tools.license import TAPAS_SYSTEM_LICENSE_PARAMETER


def get_params():
    return [
        TAPAS_SYSTEM_LICENSE_PARAMETER,
    ]

Init git repository¶

Tapas can init git repository. To add init git repo prompt add TAPAS_SYSTEM_INIT_GIT_PARAMETER to get_params function:

from tapas.tools.git import TAPAS_SYSTEM_INIT_GIT_PARAMETER


def get_params():
    return [
        TAPAS_SYSTEM_INIT_GIT_PARAMETER,
    ]

post_init function¶

post_init function (if present) will be called after project generation but before tapas system calls. There is no any restriction on what can be in this function.

Possible use cases:

• Fine tuning of generated files (e.g. chmod)

Publishing your tapa¶

The best place to publish your tapa is github. Simply create repository and publish all tapa files in it.

Adding your tapa to tapas-index¶

To provide possibility to use your tapa via its name you should add record to index.yml file in tapas-index repository.

Please check requirements in contributing section.