Contributing

Contributions to the ESPHome suite are very welcome! All the code for the projects is hosted on GitHub and you can find the sources here:

Just clone the repository locally, do the changes for your new feature/bug fix and submit a pull request. I will try to take a look at your PR as soon as possible.

Contributing to ESPHome-Docs

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One of the areas of ESPHome that can always be improved is the documentation. If you see an issue somewhere, or spelling mistakes or if you want to share your awesome setup, please feel free to submit a pull request.

The ESPHome documentation is built using sphinx and uses reStructuredText for all source files.

Syntax

In my opinion, markdown would have been the much better choice in hindsight, but at the time I was setting up the documentation good doxygen integration was key to me. Anyway, here’s a quick RST primer:

  • Headers: You can write titles like this:

    My Title
    ========
    

    and section headers like this:

    My Sub Section
    --------------
    

    and sub-section headers like this:

    My Sub-sub section
    ******************
    
  • Links: To create a link to an external resource (for example https://www.google.com), use \`Link text <link_url>\`__. For example:

    `Google.com <https://www.google.com>`__
    

    Google.com

  • References: To reference another document, use the :doc: and :ref: roles (references are set up globally and can be used between documents):

    .. _my-reference-label:
    
    Section to cross-reference
    ^^^^^^^^^^^^^^^^^^^^^^^^^^
    
    See :ref:`my-reference-label`, also see :doc:`/components/switch/gpio`.
    :doc:`Using custom text </components/switch/gpio>`.
    

    See Devices, also see GPIO Switch. Using custom text.

  • Inline code: To have text appear like this, use double backticks:

    To have text appear ``like this``, use double backticks.
    

    To have text appear like this, use double backticks.

  • Code blocks: To show a sample configuration file, use the code-block directive:

    .. code-block:: yaml
    
        # Sample configuration entry
        switch:
          - platform: gpio
            name: "Relay #42"
            pin: GPIO13
    
    # Sample configuration entry
    switch:
      - platform: gpio
        name: "Relay #42"
        pin: GPIO13
    

    Note

    Please note the empty line after the code-block directive. That is necessary.

  • Images: To show images, use the figure directive:

    .. figure:: images/dashboard.png
        :align: center
        :width: 40.0%
    
        Optional figure caption.
    
    https://d33wubrfki0l68.cloudfront.net/81e443c309e782d2e1e34a6793af4ef66aae0b25/8b63b/_images/dashboard.png

    Optional figure caption.

    Note

    All images in the documentation need to be as small as possible to ensure fast page load times. For normal figures the maximum size should be at most about 1000x800px or so. Additionally, please use online tools like https://tinypng.com/ or https://tinyjpg.com/ to further compress images.

  • Notes and warnings: You can create simple notes and warnings using the note and warning directives:

    .. note::
    
         This is a note.
    
    .. warning::
    
         This is a warning.
    

    Note

    This is a note.

    Warning

    This is a warning.

  • Italic and boldface font families: To italicize text, use one asterisk around the text. To put a strong emphasis on a piece of text, put two asterisks around it.

    *This is italicized.* (A weird word...)
    **This is very important.**
    

    This is italicized. (A weird word…) This is very important.

  • Ordered and unordered list: The syntax for lists in RST is more or less the same as in markdown:

    - Unordered Item
    
      - Unordered Sub-Item
    
    - Item with a very long text so that it does not fully fit in a single line and
      must be split up into multiple lines.
    
    1. Ordered Item #1
    2. Ordered Item #2
    
    • Unordered Item
      • Unordered Sub-Item
    • Item with a very long text so that it does not fully fit in a single line and must be split up into multiple lines.
    1. Ordered Item #1
    2. Ordered Item #2
  • imgtable: ESPHome uses a custom RST directive to show the table on the front page (see index.rst). New pages need to be added to the imgtable list. The syntax is CSV with <PAGE NAME>, <FILE NAME> (without RST), <IMAGE> (in top-level images/ directory). The aspect ratio of these images should be 8:10 (or 10:8) but exceptions are possible.

    Because these images are served on the main page, they need to be compressed heavily. SVGs are prefered over JPGs and JPGs should be max. 300x300px. If you have imagemagick installed, you can use this command to convert the thumbnail:

    convert -sampling-factor 4:2:0 -strip -interlace Plane -quality 80% -resize 300x300 in.jpg out.jpg
    

reStructured text can do a lot more than this, so if you’re looking for a more complete guide please have a look at the Sphinx reStructuredText Primer.

Build

Note

The easiest way is to use the esphome-docs docker image:

docker run --rm -v "${PWD}/":/data -p 8000:8000 -it esphome/esphome-docs

And then go to <CONTAINER_IP>:8000 in your browser.

This way, you don’t have to install the dependencies to build the documentation.

To check your documentation changes locally, you first need install sphinx (with Python 3).

# in ESPHome-Docs repo:
pip3 install -r requirements.txt

Then, use the provided Makefile to build the changes and start a simple web server:

# Start web server on port 8000
make webserver

# Updates then happen via:
make html

Notes

Some notes about the docs:

  • Use the english language (duh…)
  • An image tells a thousand words, please use them wherever possible. But also don’t forget to shrink them, for example I often use https://tinypng.com/
  • Try to use examples as often as possible (also while it’s great to use highly accurate, and domain-specific lingo, it should not interfere with new users understanding the content)
  • When adding new files, please also add them to the index.rst file in the directory you’re editing.
  • Fixes/improvements for the docs themselves should go to the current branch of the esphomedocs repository. New features should be added against the next branch.

Setting Up Development Environment

For developing new features to ESPHome, you will first need to set up a development environment. This is only possible for pip installs.

# Clone repos
git clone https://github.com/esphome/esphome.git
git clone https://github.com/esphome/esphome-core.git
git clone https://github.com/esphome/esphome-docs.git

# Install esphome, python 2!
cd esphome/
pip2 install -e .
pip2 install flake8==3.6.0 pylint==1.9.4 pillow
# Start a new feature branch
git checkout -b my-new-feature
cd ..

# Setup esphome-core environment
cd esphome-core/
pio init --ide vscode  # See 'pio init -h' for options
git checkout -b my-new-feature

Now you can open esphome-core in your IDE of choice (mine is CLion) with the platformio addons (see platformio docs for more info). Then develop the new feature with the guidelines below.

Next, for the python part of the feature you can again use any IDE you want (I use PyCharm) and develop the feature. You can create a config/ folder inside the esphome repo to store configs you’re working with (automatically excluded by .gitignore).

To compile against your local esphome-core in esphome youhave to give the path to the esphome core in esphome_core_version:

esphome:
  esphome_core_version:
    local: path/to/esphome-core

To perform style checks for your changes (which are enforced by travis-ci) you can run

flake8 esphome
pylint esphome

Finally, for documentation changes go to your esphome-docs folder, and install sphinx (with Python 3!)

pip3 install sphinx
make webserver

Or alternatively just submit a draft PR to the docs repo and wait for netlify to create a build preview.

Contributing to ESPHome-Core

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ESPHome-Core is the engine behind all the ESPHome stuff. To contribute code to ESPHome-Core to fix a bug or add a new integration/feature, clone the repository, make your changes and create a pull request.

At some point, I will create a dedicated guide for the exact setup used, but for now just look around the code base a bit and see how other components are doing stuff.

To initialize the development environment, navigate to the repository and execute:

# View available IDEs:
pio init --help
# Initialize for IDE
pio init --ide {YOUR_IDE}

Standard for the esphome-core codebase:

  • All features should at least have a bit of documentation using the doxygen documentation style (see other source files for reference)
  • The code style is based on the Google C++ Style Guide with a few modifications.
  • function, method and variable names are lower_snake_case
  • class/struct/enum names should be UpperCamelCase
  • constants should be UPPER_SNAKE_CASE
  • fields should be protected and lowe_snake_case_with_trailing_underscore_ (NOT private)
  • It’s preferred to use long variable/function names over short and non-descriptive ones.
  • All uses of class members should be prefixed with this-> to distinguish class from global functions in code review.
  • Use two spaces, not tabs.
  • Using #define s is discouraged and should be replaced by constants.
  • Use using type_t = int; instead of typedef int type_t;
  • Be careful with including large standard library headers, they can considerably increase the code size.
  • All features should only be compiled if a user explicitly defined so using -DUSE_<FEATURE> (see esphome/defines.h)
  • Header files .h should not include source code. All code should sit in C++ .cpp files. (except for templates)
  • Using explicit int sizes is like int64_t is preferred over standard types like long long.
  • All new features should have at least one example usage in the examples directory.
  • New components should dump their configuration using ESP_LOGCONFIG at startup in setup()
  • The number of external libraries should be kept to a minimum. If the component you’re developing has a simple communication interface, please consider implementing the library natively in ESPHome.
  • Implementations for new devices should contain reference links for the datasheet and other sample implementations.
  • Please test your changes :)

For editing a local copy of esphome-core within the ESPHome ecosystem please see esphome.esphome_core_version option.

Contributing to ESPHome

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ESPHome primarily does two things: It validates the configuration and creates C++ code.

The configuration validation should always be very strict with validating user input - it’s always better to fail quickly if a configuration isn’t right than to have the user find out the issue after a few hours of debugging.

Preferably, the configuration validation messages should explain the exact validation issue (and not “invalid name!”) and try to suggest a possible fix.

The C++ code generation engine is 99% syntactic sugar and unfortunately not too well documented yet. Have a look around other components and you will hopefully quickly get the gist of how to interact with the code generation engine.

The python source code of your component will automatically be loaded if the user uses it in the configuration. Specifically, it may contain these fields:

  • CONFIG_SCHEMA: for components like dallas. This is the configuration schema that will be validated against the user configuration.

  • PLATFORM_SCHEMA: for platforms like sensor.dallas. This is the configuration schema that will be validated against every platform: definition in the config of your platform name.

  • to_code: The “workhorse” of ESPHome. This will be called with the configuration of your component/platform and you can add code to the global code index in here.

    • Call an Application method like this App.make_dallas_component()

    • Register a variable using variable(<TYPE>, <VAR_ID>, rhs). This will generate an assignment expression and add it to the global expression index. The return value is the left hand side variable which you can use for further calls.

      <TYPE> <VAR_ID> = <rhs>;
      
    • Register a variable of a pointer type using Pvariable(<TYPE>, <VAR_ID>, rhs).

      <TYPE> *<VAR_ID> = <rhs>;
      
      // rhs = App.make_dallas_component(12, 15000)
      // var = Pvariable(DallasComponent, "dallas_id", rhs)
      // add(var.hello_world())
      DallasComponent *dallas_id = App.make_dallas_component(12, 15000)
      dallas_id->hello_world()
      
    • Expressions like var.hello_world() are not automatically added to the code and need to be added to the global expression index using add().

    • Access variables using get_variable(). The variable will automatically know if it is a pointer and use the correct operator. Additionally, you can pass a type as the second argument to get_variable. This will cause ESPHome to use the first variable of that type.

      hub = get_variable(config.get(CONF_DALLAS_ID), DallasComponent)
      
    • Pass configuration arguments to mock function calls (like App.make_dallas_component) using normal python :)

      rhs = App.make_dallas_component(config[CONF_PIN], config.get(CONF_UPDATE_INTERVAL))
      

      Note the config.get(): Trailing None values in function calls are stripped.

  • BUILD_FLAGS: Pass build flags that should be provided if your component is loaded.

    BUILD_FLAGS = '-DUSE_DALLAS_SENSOR'
    
  • REQUIRED_BUILD_FLAGS: Like BUILD_FLAGS, but also uses these build flags if the user has disabled build flags in the esphome section.

  • DEPENDENCIES: Other components that are required to be in the user’s configuration if this platform/component is loaded:

    DEPENDENCIES = ['i2c']
    
  • ESP_PLATFORMS: Provide a whitelist of platforms this integration works on. Default is work on all platforms.

    ESP_PLATFORMS = [ESP_PLATFORM_ESP32]
    

Run pip2 install -e . to install a development version of ESPHome.