Why #egg=foo when pip-installing from git repo
PythonPackagePipPython Problem Overview
When I do a "pip install -e ..." to install from a git repo, I have to specify #egg=somename or pip complains. For example:
pip install -e git://github.com/hiidef/oauth2app.git#egg=oauth2app
What's the significance of this "egg" string?
Python Solutions
Solution 1 - Python
per pip install -h the "egg" string is the directory that gets checked out as part of the install
Solution 2 - Python
An Egg is just some bundled python code. In a git url, the egg is the project name. VCS Support
Normally we install python packages from Pypi, so you specify ONLY the package name and version (or it assumes latest version if you don't specify). Pypi then searches for which egg you want and pip installs that. pip install celery would install the latest published egg and pip install celery[redis] would install a different egg that contains the same celery package and also installs the the latest eggs from whatever packages were listed as dependencies for redis in celery's setup.py.
With git and gitlab paths, you specify /{user|group}/{repository}.git@{tag}#egg={package-name}. there is a difference between #egg=celery and #egg=celery[redis], but they will both come from the same source code.
"tag" can also be a branch or commit hash in addition to an actual tag. It is assumed to be master if you do not specify.
for example, git+https://github.com/celery/celery.git#egg=celery==4.3.0 would check out the master branch and install that. Even though you specified a version number, it is not taken into account in the installation. THE VERSION NUMBER IS IGNORED
When installing via git or other VCS urls, you will want to find the tag or hash of the version you need. For example, git+https://github.com/celery/[email protected]#egg=celery which will checkout the commit tagged "v4.3.0" and then install the package from that source code. Assuming the maintainers did not egregiously mis-tag their repositories, you can get the version you want like that.
Solution 3 - Python
https://pip.pypa.io/en/stable/reference/pip_install/#vcs-support says:
> The "project name" component of the url suffix "egg=
From this I deduce that the egg value is only used for dependency checks and therefore I think, by convention, the package name (i.e. some-pypi-package-name) should be used, not any contained folder (i.e. some_pypi_package_name)
Solution 4 - Python
You have to include #egg=Package so pip knows what to expect at that URL. See https://pip.pypa.io/en/stable/reference/pip_install/#vcs-support
Solution 5 - Python
Quoting the manual:
> pip looks at 2 fragments for VCS URLs: > > egg: For specifying the “project name” for use in pip’s dependency > resolution logic. eg: egg=project_name > > subdirectory: For specifying the path to the Python package, when it > is not in the root of the VCS directory. eg: pkg_dir