Adding Repositories to your Project

What is a Repository

A repository is a version-ed Mynewt project, which is a collection of Mynewt packages organized in a specific way for redistribution.

What differentiates a repository from a Mynewt project is the presence of a repository.yml file describing the repository. This will be described below. For a basic understanding of repositories you may read the Newt Tool Guide and How to create repos.

Note: For the remainder of this document we’ll use the term repo as shorthand for a Mynewt repository.

Repos are useful because they are an organized way for the community to share Mynewt packages and projects. In fact, the Mynewt-core is distributed as a repo.

Why does Mynewt need additional repos?

Repos add functionality not included in the Mynewt core. New repos might be created for several reasons.

  • Expertise. Individuals or organizations may have expertise that they want to share in the form of repos. For example a chip vendor may create a repo to hold the Mynewt support for their chips.
  • Non-Core component. Some components, although very useful to Mynewt users are not core to all Mynewt users. These are likely candidates to be held in different repos.
  • Software licensing. Some software have licenses that make them incompatible with the ASF (Apache Software Foundation) license policies. These may be valuable components to some Mynewt users, but cannot be contained in the apache-mynewt-core.

What Repos are in my Project

The list of repos used by your project are contained within the project.yml file. An example can be seen by creating a new project:

$ mkdir ~/dev
$ cd ~/dev
$ newt new myproj
$ cd myproj

View the project.yml section and you will see a line describing the repos:

project.repositories:
    - apache-Mynewt-core

By default, this newly created project uses a single repo called apache-Mynewt-core.

If you wish to add additional repos, you would add additional lines to the project.repositories variable like this.

Repo Descriptors

In addition to the repo name, the project.yml file must also contain a repo descriptor for each repository you include that gives newt information on obtaining the repo.

In the same myproj above you will see the following repo descriptor.

repository.apache-Mynewt-core:
    type: github
    vers: 1-latest
    user: apache
    repo: mynewt-core

A repo descriptor starts with repository.<name>.. In this example, the descriptor specifies the information for the apache-Mynewt-core.

The fields within the descriptor have the following definitions:

  • type – The type of code storage the repo uses. The current version of newt only supports github. Future versions may support generic git or other code storage mechanisms.
  • vers – The version of the repo to use for your project. A source code repository contains many versions of the source. This field is used to specify the one to use for this project. See the section on versions below for a detailed description of the format of this field.
  • user – The username for the repo. On github, this is the name after github.com in the repo path. Consider the repository https://github.com/apache/mynewt-core. It has username apache.
  • repo – The name of the repo. On github, this is the name after the username described above. Consider the repository https://github.com/apache/mynewt-core. It has path mynewt-core. This is a path to the source control and should not be confused with the name of the repo that you used in the repository.<name> declaration above. That name is contained elsewhere within the repo. See Below.

Adding Existing Repos to my Project

To add a new repo to your project, you have to complete two steps.

  • Edit the project.yml file and add a new repo descriptor. The previous section includes information on the field required in your repo descriptor.
  • Edit the project/yml file and add a new line to the project.repositories variable with the name of the repo you are adding.

An example of a project.yml file with two repositories is shown below:

project.name: "my_project"

project.repositories:
    - apache-mynewt-core
    - mynewt_arduino_zero

# Use github's distribution mechanism for core ASF libraries.
# This provides mirroring automatically for us.
#
repository.apache-mynewt-core:
    type: github
    vers: 1-latest
    user: apache
    repo: mynewt-core

# a special repo to hold hardware specific stuff for arduino zero
repository.mynewt_arduino_zero:
    type: github
    vers: 1-latest
    user: runtimeco
    repo: mynewt_arduino_zero

What Version of the Repo to use

Mynewt repos are version-ed artifacts. They are stored in source control systems like github. The repo descriptor in your project.yml file must specify the version of the repo you will accept into your project.

For now, we are at the beginnings of Mynewt. For testing and evaluation please use 1-latest in the vers field in your repo descriptor.

vers:1-latest

See Create a Repo for a description of the versioning system and all the possible ways to specify a version to use.

Identifying a Repo

A repo contains Mynewt packages organized in a specific way and stored in one of the supported code storage methods described above. In other words, it is a Mynewt project with an additional file repository.yml which describes the repo for use by newt (and humans browsing them). It contains a mapping of version numbers to the actual github branches containing the source code.

Note that the repository.yml file lives only in the master branch of the git repository. Newt will always fetch this file from the master branch and then use that to determine the actual branch required depending on the version specified in your project.yml file. Special care should be taken to ensure that this file exists only in the master branch.

Here is the repository.yml file from the apache-mynewt-core:

repo.name: apache-mynewt-core
repo.versions:
    "0.0.0": "master"
    "0.0.1": "master"
    "0.7.9": "mynewt_0_8_0_b2_tag"
    "0.8.0": "mynewt_0_8_0_tag"
    "0.9.0": "mynewt_0_9_0_tag"
    "0.9.9": "mynewt_1_0_0_b1_tag"
    "0.9.99": "mynewt_1_0_0_b2_tag"
    "0.9.999": "mynewt_1_0_0_rc1_tag"
    "1.0.0": "mynewt_1_0_0_tag"

    "0-latest": "1.0.0"    # 1.0.0
    "0-dev": "0.0.0"       # master

    "0.8-latest": "0.8.0"
    "0.9-latest": "0.9.0"
    "1.0-latest": "1.0.0"  # 1.0.0

It contains the following:

  • repo.name The external name that is used to include the library in your project.yml file. This is the name you in include in the project.repositories variable when adding this repository to your project.
  • repo.versions A description of what versions to give the user depending on the settings in their project.yml file.

Repo Version

The repo version number resolves to an actual git branch depending on the mapping specified in repository.yml for that repo. The version field argument in your project.yml file supports multiple formats for flexibility:

<major_num>.<minor_num>.<revision_num>

or

<major_num>.<minor_num>-<stability string>

or

<major_num>-<stability string>

The stability string can be one of 3 pre-defined stability values.

  1. stable – A stable release version of the repository
  2. dev – A development version from the repository
  3. latest – The latest from the repository

In your project.yml file you can specify different combinations of the version number and stability value. For example:

  • 1-latest – The latest version with major number 1
  • 1.2-stable – The latest stable version with major and minor number 1.2
  • 1.2-dev – The development version from 1.2
  • 1.1.1 – a specific version 1.1.1

You cannot specify a stability string with a fully numbered version, e.g.

1.2.8-stable

Repo Versions Available

A repository.yml file contains information to match a version request into a git branch to fetch for your project.

It’s up to the repository maintainer to map these to branches of the repository. For example, let’s say in a fictitious repository the following are defined.

repo.versions:
    "0.8.0": "xxx_branch_0_8_0"
    "1.0.0": "xxx_branch_1_0_0"
    "1.0.2": "xxx_branch_1_0_2"
    "1.1.1": "xxx_branch_1_1_0"
    "1.1.2": "xxx_branch_1_1_2"
    "1.2.0": "xxx_branch_1_2_0"
    "1.2.1": "xxx_branch_1_2_1"
    "1.2-dev": "1.2.1"
    "1-dev": "1.2-dev"
    "1.2-stable": "1.2.0"
    "0-latest": "0.8.0"
    "1-latest": "1-dev"
    ....

When the project.yml file asks for 1.2-stable it is resolved to version 1.2.0 (perhaps 1.2.1 is not stable yet), which in turn resolves to a specific branch xxx_branch_1_2_0. This is the branch that newt fetches into your project.

Note: Make sure a repo version exists in the repository.yml file of a repo you wish to add. Otherwise Newt will not be able to resolve the version and will fail to fetch the repo into your project.

How to find out what Repos are available for Mynewt components

Currently, there is no newt command to locate/search Mynewt package repositories. However, since the newt tool supports only github, searching github by keyword is a satisfactory option until a search tool is created.

When searching Github, recall that a Mynewt repository must have a repository.yml file in its root directory. If you don’t see that file, it’s not a Mynewt repository and can’t be included in your project via the newt tool.

Once you find a repository, the Github URL and repository.yml file should give you all the information to add it to your project.yml file.