Project Structure

The project is a set of files on the disk and, of course, in a version control system. You are creating new project with mantil new. That creates project structure and nothing more. Until you create a project stage project don't have anything but files on the disk.

In Mantil we choose to favor convention over configuration. A big part of that convention is in the Mantil project structure. Let's look into an example Mantil project with two API's: ping and second.

├── api
│   ├── ping
│   │   ├── ping.go
│   │   └── ping_test.go
│   └── second
│       └── second.go
├── build
│   └── functions
│       ├── ping
|       |   ├── main.go
|       |   └── bootstrap
│       └── second
|           ├── main.go
|           └── bootstrap
├── config
│   ├── environment.yml
│   └── state.yml
├── go.mod
├── go.sum
├── public
│   ├── api.js
│   ├── index.html
│   └── style.css
└── test
    ├── init.go
    ├── ping_test.go
    └── second_test.go

API

API folder is a set of Go packages where each package after deployment will become exposed on the endpoint URL.

The package needs to have exported _New method, which returns a pointer to the struct. That struct will be exposed at endpoint/package-name URL. Where endpoint is stage endpoint URL.

The package named ping from the example will be exposed at endpoint/ping. All exported packages methods will be exposed at endpoint/ping/method-name. If the package has the method named Default, that method is mapped to the package root endpoint/ping. For example if the stage HTTP endpoint is https://lh5rfrc3gf.execute-api.eu-central-1.amazonaws.com URLs of the package ping methods will be:

URL	Go method in ping.Ping struct
https://lh5rfrc3gf.execute-api.eu-central-1.amazonaws.com/ping	Default
https://lh5rfrc3gf.execute-api.eu-central-1.amazonaws.com/ping/hello	Hello
https://lh5rfrc3gf.execute-api.eu-central-1.amazonaws.com/ping/reqrsp	ReqRsp

The method needs to have a specific signature to be used by Mantil in API URLs. Method needs to be exported and must follow these rules:

• may take between 0 and two arguments.
• if there are two arguments, the first argument must satisfy the "context.Context" interface.
• may return between 0 and two arguments.
• if there are two return values, the second argument must be an error.
• if there is one return value, it must be an error.

valid signatures are:

   func ()
   func () error
   func (TIn) error
   func () (TOut, error)
   func (context.Context) error
   func (context.Context, TIn) error
   func (context.Context) (TOut, error)
   func (context.Context, TIn) (TOut, error)

The same as rules as for default AWS Go handler with the added convention that each method in the API struct is exposed as a URL path.

Public folder

A public folder is a place for your static site content. Put an index.html file in the /public folder, and it will be visible at the endpoint root.

Build folder

The build folder is automatically generated on each deploy and contains the main package for each API which is code that transforms your API's to Lambda functions. Binaries of your functions named bootstrap are also placed in this folder. If you're using source control, this folder should be untracked by adding it to your .gitignore file since all data is generated on each deploy. This is automatically done for you when initializing project with new command.

Code in build folder uses Mantil Go SDK to transform your API's to AWS Lambda functions.

Config folder

In config folder environment.yml is a place where you can set environment variables for each Stage. So you can configure different behavior in different stages.
state.yml is a project database file maintained by Mantil. It is stored in the project so you can see the history of all changes. You should not edit this file.

Test

Test folder if where your API end to end tests are stored. Explore ping example to get an idea of how to create requests and explore results. Read more about testing in Mantil.