Code and Project Conventions

Conventions and standards that guide the development and arrangement of Airship component projects.

Project Structure

Charts

Each project that maintains helm charts will keep those charts in a directory charts located at the root of the project. The charts directory will contain subdirectories for each of the charts maintained as part of that project. These subdirectories should be named for the component represented by that chart.

e.g.: For project foo, which also maintains the charts for bar and baz:

  • foo/charts/foo contains the chart for foo

  • foo/charts/bar contains the chart for bar

  • foo/charts/baz contains the chart for baz

Helm charts utilize the helm-toolkit supported by the Openstack-Helm team and follow the standards documented there.

Images

Each project that creates a Docker image will keep the dockerfile in a directory images located at the root of the project. The images directory will contain subdirectories for each of the images created as part of that project. The subdirectory will contain the dockerfile that can be used to generate the image.

e.g.: For project foo, which also produces a Docker image for bar:

  • foo/images/foo contains the dockerfile for foo

  • foo/images/bar contains the dockerfile for bar

Makefile

Each project must provide a makefile at the root of the project. The makefile should implement each of the following makefile targets:

  • images will produce the docker images for the component and each other component it is responsible for building.

  • charts will helm package all of the charts maintained as part of the project.

  • lint will perform code linting for the code and chart linting for the charts maintained as part of the project, as well as any other reasonable linting activity.

  • dry-run will produce a helm template for the charts maintained as part of the project.

  • all will run the lint, charts, and images targets.

  • docs should render any documentation that has build steps.

  • run_{component_name} should build the image and do a rudimentary (at least) test of the image’s functionality.

  • run_images performs the inidividual run_{component_name} targets for projects that produce more than one image.

  • tests to invoke linting tests (e.g. PEP-8) and unit tests for the components in the project

  • format to invoke automated code formatting specific to the project’s code language (e.g. Python for armada and Go for airshipctl) as listed in the Linting and Formatting Standards.

For projects that are Python based, the makefile targets typically reference tox commands, and those projects will include a tox.ini defining the tox targets. Note that tox.ini files will reside inside the source directories for modules within the project, but a top-level tox.ini may exist at the root of the repository that includes the necessary targets to build documentation.

Documentation

Also see Documentation

Documentation source for the component should reside in a ‘docs’ directory at the root of the project.

Linting and Formatting Standards

Code in the Airship components should follow the prevalent linting and formatting standards for the language being implemented. In lieu of industry accepted code formatting standards for a target language, strive for readability and maintainability.

Known Standards

Language

Tools Used

Go

gofmt

Python

YAPF, Flake8

Go Formatting

Go code should be formatted using gofmt. When using gofmt be sure to use the -s flag to include simplification of code for example:

gofmt -s /path/to/file.go

Python PEP-8 Formatting

Python should be formatted via YAPF, the knobs for YAPF can be specified in the project’s root directory in ‘.style.yapf’ the contents of this file should be:

[style]
based_on_style = pep8
spaces_before_comment = 2
column_limit = 79
blank_line_before_nested_class_or_def = false
blank_line_before_module_docstring = true
split_before_logical_operator = true
split_before_first_argument = true
allow_split_before_dict_value = false
split_before_arithmetic_operator = true

A sample Flake8 section is below, for use in tox.ini, and is the method of enforcing import orders via Flake8 extension flake8-import-order:

[flake8]
filename = *.py
show-source = true
# [H106] Don't put vim configuration in source files.
# [H201] No 'except:' at least use 'except Exception:'
# [H904] Delay string interpolations at logging calls.
enable-extensions = H106,H201,H904
# [W503] line break before binary operator
ignore = W503
exclude=.venv,.git,.tox,build,dist,*lib/python*,*egg,tools,*.ini,*.po,*.pot
max-complexity = 24

Airship components must provide for automated checking of their formatting standards, such as the lint step noted above in the makefile. Components may provide automated reformatting.

Tests Location

Tests should be in parallel structures to the related code, unless dictated by target language ecosystem.

For Python projects, the preferred location for tests is a tests directory under the directory for the module. E.g. Tests for module foo: {root}/src/bin/foo/foo/tests. An alternataive location is tests at the root of the project, although this should only be used if there are not multiple components represented in the same repository, or if the tests cross the components in the repository.

Each type of test should be in its own subdirectory of tests, to allow for easy separation. E.g. tests/unit, tests/functional, tests/integration.

Source Code Location

A standard structure for the source code places the source for each module in a module-named directory under either /src/bin or /src/lib, for executable modules and shared library modules respectively. Since each module needs its own setup.py and setup.cfg (python) that lives parallel to the top-level module (i.e. the package), the directory for the module will contain another directory named the same.

For example, Project foo, with module foo_service would have a source structure that is /src/bin/foo_service/foo_service, wherein the __init__.py for the package resides.

Sample Project Structure (Python)

Project foo, supporting multiple executable modules foo_service, foo_cli, and a shared module foo_client

{root of foo}
 |- /doc
 |    |- /source
 |    |- requirements.txt
 |- /etc
 |    |- /foo
 |         |- {sample files}
 |- /charts
 |    |- /foo
 |    |- /bar
 |- /images
 |    |- /foo
 |    |    |- Dockerfile
 |    |- /bar
 |         |- Dockerfile
 |- /tools
 |    |- {scripts/utilities supporting build and test}
 |- /src
 |    |- /bin
 |    |    |- /foo_service
 |    |    |    |- /foo_service
 |    |    |    |    |- __init__.py
 |    |    |    |    |- {source directories and files}
 |    |    |    |- /tests
 |    |    |    |    |- unit
 |    |    |    |    |- functional
 |    |    |    |- setup.py
 |    |    |    |- setup.cfg
 |    |    |    |- requirements.txt (and related files)
 |    |    |    |- tox.ini
 |    |    |- /foo_cli
 |    |         |- /foo_cli
 |    |         |    |- __init__.py
 |    |         |    |- {source directories and files}
 |    |         |- /tests
 |    |         |    |- unit
 |    |         |    |- functional
 |    |         |- setup.py
 |    |         |- setup.cfg
 |    |         |- requirements.txt (and related files)
 |    |         |- tox.ini
 |    |- /lib
 |         |- /foo_client
 |              |- /foo_client
 |              |    |- __init__.py
 |              |    |- {source directories and files}
 |              |- /tests
 |              |    |- unit
 |              |    |- functional
 |              |- setup.py
 |              |- setup.cfg
 |              |- requirements.txt (and related files)
 |              |- tox.ini
 |- Makefile
 |- README  (suitable for github consumption)
 |- tox.ini (primarily for the build of repository-level docs)

Note that this is a sample structure, and that target languages may preclude the location of some items (e.g. tests). For those components with language or ecosystem standards contrary to this structure, ecosystem convention should prevail.