Platforms and Python Tags

Brood identifies platforms and Python runtime compatibility based on identification strings. This section describes how to discover the valid platforms and Python tags using hatcher.

Platforms

Platforms describe the operating system and system architecture compatibility of an egg, runtime or app.

Listing current platforms recognized by a brood server

In order to follow the next examples, the available platform support of Brood is required. This command lists all valid platforms in Brood:

$ hatcher platforms list
osx-x86_64
osx-x86
rh5-x86_64
rh5-x86
win-x86_64
win-x86

These are the valid values for any command that requires specifying a platform. For example, to list the eggs in the enthought/free repository for the rh5-x86_64 platform, the following command is used:

$ hatcher eggs list enthought free rh5-x86_64 cp27

Example Valid Platforms

As of Brood v0.3.1, the following platforms are recognized:

Brood Platform Operating System System Architecture
osx-x86_64 Apple Mac OSX x86_64
osx-x86 Apple Mac OSX x86
rh5-x86_64 RedHat Linux 5.x x86_64
rh5-x86 RedHat Linux 5.x x86
win-x86_64 Microsoft Windows x86_64
win-x86 Microsoft Windows x86

Python Tags

Python tags describe the runtime compatibility of an egg or app. The Python tags are used as defined in PEP425, following the actual implementation in wheel, which does not follow the spec exactly.

Python tags are used to indicate both which Python implementation a package requires (if any), as well as the version required. The tag is made up of two portions which describe this relationship. The tags defined in PEP425 take the following form:

  • First two characters contain Python implementation description
  • Final one or two characters are the Major and Minor version of the Python implementation. Brood (as wheel) use the Major and Minor version of the Python language that the implementation provides.

For example:

  • cp27 indicates CPython 2.7.x compatibility.
  • pp27 indicates compatibility with Pypy providing Python language version 2.7.x.
  • py34 indicates that an egg has no dependency on a specific Python implementation, but requires Python language version 3.4.x.
  • jy2 indicates that an egg is compatible with any Jython version that provides Python language 2.x.

Python Tags and Eggs

When requesting an egg list or index, the Python tag of the target runtime must be provided. This is to ensure that the index returned contains only packages that will work on the target runtime. To list the possible Python tags that may be used to request the egg list for a Python implementation, use the following command:

$ hatcher python-tags list
Python Tag
------------
cp27
cp30
cp31
cp32
cp33
cp34
ip27
jy27
pp27

Each egg in Brood specifies its own Python runtime compatibility. For example, numpy requires a CPython interpreter as it depends on the CPython/C API. It may specify a Python tag like cp27 or cp32. On the other hand, nose is a pure-python egg which is compatible with multiple runtimes. It may specify Python tags like py2 and py3. When listing eggs with hatcher, the eggs specific runtime tag is listed along with it, so that the correct egg may be manipulated with hatcher:

$ hatcher eggs list enthought free rh5-64 cp27
Egg Name          Python Tag
----------------  ------------
nose-1.3.0-1.egg  py2
...

The Python tag listed alongside the egg is used to download the egg:

$ hatcher eggs download enthought free rh5-64 py2 nose 1.3.0-1
...