# Creating your own Bitrise project scanner

The project scanner is a tool that identifies the given project’s type and generates a basic Bitrise configuration. Each supported project type has its own scanner: these scanners are stored as separate packages.

A project type scanner defines at least two workflows: one for testing (primary) and one for building (deploy). It includes the minimal amount of Steps to successfully run them.

### Build and test Steps

Build Steps and test Steps have specific requirements:

• a build Step must build your app so that it is ready for deployment and it must output an Environment Variable that points to the output file(s). For example, a build Step to build an iOS app must output an .ipa file (not, say, .xcodearchive) and the path to this .ipa file.

• a test Step must output the test results so that they are available for viewing on the build page on bitrise.io.

When adding a new project on the website or initializing a project on your own machine, the bitrise-init tool iterates through every scanner, calls the scanner interface methods on each of them and collects their outputs. Based on these outputs, a basic configuration is generated.

The possible workflows are described in a scan result model. The model consists of:

• options

• configs

• warnings

Here is the basic structure of the model, in YAML:

options:
DETECTED_PLATFORM_1: OptionModel
DETECTED_PLATFORM_2: OptionModel
...

configs:
DETECTED_PLATFORM_1:
CONFIG_NAME_1: ConfigModel
CONFIG_NAME_2: ConfigModel
...
DETECTED_PLATFORM_2:
CONFIG_NAME_1: ConfigModel
CONFIG_NAME_2: ConfigModel
...
...

warnings:
DETECTED_PLATFORM_1:
- "warning message 1"
- "warning message 2"
...
DETECTED_PLATFORM_2:
- "warning message 1"
- "warning message 2"
...
• Every platform scanner writes its possible options, configurations and warnings into this model. These will be translated into step input values by choosing the desired values for the given options.

• Every option chain’s last option selects a configuration.

• Warnings display the issues with the given project setup.

## Options

Options represents a question and the possible answers to the question. For example:

• Question: What is the path to the iOS project files?

• Possible answers: List of possible paths to check

These questions and answers are translated into Step inputs. The scanner should either determine the input value or let the user select or type the value.

For example, the Xcode Archive & Export for iOS Step has an input called export-method. This informs the Step of the type of .ipa you want to export. The value cannot be determined based on the source code so the scanner collects every possible value and presents them to the user in the form of a list to choose from.

Selecting an option can start a chain: it can lead to different options being presented afterwards. For example, if you select an Xcode scheme that has associated test targets, it leads to different “questions”. Similarly, selecting a certain option can lead to a different workflow being generated afterwards.

### The option model

The OptionModel represents an input option. It looks like this in Go:

// OptionModel ...
type OptionModel struct {
Title  string
EnvKey string

ChildOptionMap map[string]*OptionModel
Config         string
}
• Title: the human readable name of the input.

• EnvKey: it represents the input’s key in the step model.

• ChildOptionMap: the map of the subsequent options if the user chooses a given value for the option.

For example, let’s see a scenario where you choose a value for the Scheme input. You will have a value_map in the options. The possible values are:

• SchemeWithTest

• SchemeWithoutTest

By choosing SchemeWithTest, the next option will be related to the simulator used to perform the test.

By choosing SchemeWithoutTest, the next option will be about the export method for the .ipa file.

{
"title": "Scheme",
"env_key": "scheme",
"value_map": {
"SchemeWithTest": {
"title": "Simulator name",
"env_key": "simulator_name",
...
},
"SchemeWithoutTest": {
"title": "Export method",
"env_key": "export_method",
...
}
}
}

Every option chain has a first option: this is called head. The possible values of the options can branch the option chain.

Every option branch’s last options must have a config property set. config holds the id of the generated Bitrise configuration.

An options chain’s last options cannot have a value_map.

{
"title": "Scheme",
"env_key": "scheme",
"value_map": {
"SchemeWithTest": {
"title": "Simulator name",
"env_key": "simulator_name",
"value_map": {
"-": {
"config": "bitrise_config_with_test",
}
}
},
"SchemeWithoutTest": {
"title": "Export method",
"env_key": "export_method",
"value_map": {
"development": {
"config": "bitrise_config_without_test",
},
"app-store": {
"config": "bitrise_config_without_test",
},
"config": "bitrise_config_without_test",
}
}
}
}
}


## Scanners

Scanners generate the possible options chains and the possible workflows for the options per project type. The ActiveScanner variable holds each scanner implementation. Every specific scanner implements the ScannerInterface.

// ScannerInterface ...
type ScannerInterface interface {
Name() string
DetectPlatform(string) (bool, error)

Options() (models.OptionModel, models.Warnings, error)
Configs() (models.BitriseConfigMap, error)

DefaultOptions() models.OptionModel
DefaultConfigs() (models.BitriseConfigMap, error)

ExcludedScannerNames() []string
}
• Name() string: This method is used for logging and storing the scanner output (warnings, options and configs). The scanner output is stored in map[SCANNER_NAME]OUTPUT. For example, the options for an iOS project is stored in optionsMap[ios]options.

• DetectPlatform(string) (bool, error): This method is used to determine if the given search directory contains the project type or not.

• Options() (models.OptionModel, models.Warnings, error): This method is used to generate option branches for the project. Each branch should define a complete and valid option set to build the final bitrise config model. Every option branch’s last Options has to store a configuration id, which will be filled with the selected options.

• Configs() (models.BitriseConfigMap, error): This method is used to generate the possible configs. BitriseConfigMap’s each element is a bitrise config template which will be fulfilled with the user selected option values.

• DefaultOptions() models.OptionModel and DefaultConfigs() (models.BitriseConfigMap, error) : These methods are used to generate the options and configs without scanning the given project. In this case every required step input value is provided by the user. This way even if a scanner fails, the user has an option to get started.

### Testing a scanner

To test a scanner, we require both unit tests and integration tests.

Unit tests are written using Go’s standard testing library.

For integration tests, we are validating that the project type scanners are generating the desired Bitrise configurations for an instance of the project type. To do this, we use the new scanner to scan the given sample project and we modify the generated scan result to fit our integration tests.

The reason for the modification is that the scanners are adding Steps to the generated config, but the Step versions are updated from time to time. The Step version definitions can be found at steps/const.go.

So we call bitrise-init --ci config in the sample project’s root directory, and in the generated scan_result.yml file we replace the Step versions with %s and we use fmt.Sprintf to inject the latest defined Step versions into the config.

In the integration tests, we are matching the scan_result.yml file generated by the scanner with the previously generated reference scan_result content.

### Submitting your own scanner

You can submit your own scanner to Bitrise: we will review it and integrate it to the bitrise-init tool once it’s approved!

The development path for a new scanner starts with your own sample project and ends with updating the existing Steps for your project type. Let’s go through it!

1. Find or create an open source sample app that demonstrates a typical instance of your project type.

It should include:

• a readme file (including tool versions required for updating, building and testing this project).

• a bitrise.yml file that is generated by your scanner.

2. Build and test your sample app with existing Steps or custom scripts.

3. Create the missing Steps the new project type needs.

The PR for these Steps should link the scanner PR once you created the scanner.

4. Create a scanner for your project type.

5. Run the required unit tests and integration tests.

6. Open a scanner pull request to the bitrise-init project.

It should:

• link the new project type’s sample app.

• link the new project type’s guides for testing and building.

• include an icon for the new project type - otherwise we will create one for you.

• recommend the default stack by listing the required tools for building and testing the new project type.

7. Update the existing Steps with the new project type if necessary.

The PR for these Steps should link the scanner PR.