HOWTO add "Show on GitHub" and "Edit on GitHub" links to the Sphinx sidebar

conf.py.rst

Edit on GitHub links for Sphinx

Create _ext/ and _templates/ subdirectories.

Move edit_on_github.py into the _ext/ subdirectory.

Move sourcelink.html into the _templates/ subdirectory.

Add the following after the import sys, os line

sys.path.insert(0, os.path.abspath('_ext'))

Add edit_on_github to the list of extensions

extensions = ['edit_on_github']

Configure the extension

edit_on_github_project = 'username/reponame'
edit_on_github_branch = 'master'

Make sure the template path is specified correctly

templates_path = ['_templates']

edit_on_github.py

"""
Sphinx extension to add ReadTheDocs-style "Edit on GitHub" links to the
sidebar.

Loosely based on https://github.com/astropy/astropy/pull/347
"""

import os
import warnings


__licence__ = 'BSD (3 clause)'


def get_github_url(app, view, path):
    return 'https://github.com/{project}/{view}/{branch}/{path}'.format(
        project=app.config.edit_on_github_project,
        view=view,
        branch=app.config.edit_on_github_branch,
        path=path)


def html_page_context(app, pagename, templatename, context, doctree):
    if templatename != 'page.html':
        return

    if not app.config.edit_on_github_project:
        warnings.warn("edit_on_github_project not specified")
        return

    path = os.path.relpath(doctree.get('source'), app.builder.srcdir)
    show_url = get_github_url(app, 'blob', path)
    edit_url = get_github_url(app, 'edit', path)

    context['show_on_github_url'] = show_url
    context['edit_on_github_url'] = edit_url

    # For sphinx_rtd_theme.
    context['display_github'] = True
    context['github_user'] = app.config.edit_on_github_project.split('/')[0]
    context['github_version'] = app.config.edit_on_github_branch + '/'
    context['github_repo'] = app.config.edit_on_github_project.split('/')[1]
    context['source_suffix'] = app.config.source_suffix[0]

def setup(app):
    app.add_config_value('edit_on_github_project', '', True)
    app.add_config_value('edit_on_github_branch', 'master', True)
    app.connect('html-page-context', html_page_context)

sourcelink.html

{%- if show_source and has_source and sourcename %}
  <h3>{{ _('This Page') }}</h3>
  <ul class="this-page-menu">
    <li><a href="{{ pathto('_sources/' + sourcename, true)|e }}"
           rel="nofollow">{{ _('Show Source') }}</a></li>
  {%- if show_on_github_url %}
    <li><a href="{{ show_on_github_url }}"
           rel="nofollow">{{ _('Show on GitHub') }}</a></li>
  {%- endif %}
  {%- if edit_on_github_url %}
    <li><a href="{{ edit_on_github_url }}"
           rel="nofollow">{{ _('Edit on GitHub') }}</a></li>
  {%- endif %}
  </ul>
{%- endif %}

The code is broken in the latest version of sphinx.
An example of how the generated link looks like it looks like

https://github.com/user/project//master/doc/installation/index.rst

instead of

https://github.com/user/project/blob/master/doc/installation/index.rst

Works great! Thanks.