# sphinx.ext.intersphinx – Link to other projects’ documentation¶

New in version 0.5.

This extension can generate automatic links to the documentation of objects in other projects.

Usage is simple: whenever Sphinx encounters a cross-reference that has no matching target in the current documentation set, it looks for targets in the documentation sets configured in intersphinx_mapping. A reference like :py:class:zipfile.ZipFile can then link to the Python documentation for the ZipFile class, without you having to specify where it is located exactly.

When using the “new” format (see below), you can even force lookup in a foreign set by prefixing the link target appropriately. A link like :ref:comparison manual <python:comparisons> will then link to the label “comparisons” in the doc set “python”, if it exists.

Behind the scenes, this works as follows:

• Each Sphinx HTML build creates a file named objects.inv that contains a mapping from object names to URIs relative to the HTML set’s root.

• Projects using the Intersphinx extension can specify the location of such mapping files in the intersphinx_mapping config value. The mapping will then be used to resolve otherwise missing references to objects into links to the other documentation.

• By default, the mapping file is assumed to be at the same location as the rest of the documentation; however, the location of the mapping file can also be specified individually, e.g. if the docs should be buildable without Internet access.

## Configuration¶

To use Intersphinx linking, add 'sphinx.ext.intersphinx' to your extensions config value, and use these config values to activate linking:

intersphinx_mapping

This config value contains the locations and names of other projects that should be linked to in this documentation.

Relative local paths for target locations are taken as relative to the base of the built documentation, while relative local paths for inventory locations are taken as relative to the source directory.

When fetching remote inventory files, proxy settings will be read from the \$HTTP_PROXY environment variable.

Old format for this config value

This is the format used before Sphinx 1.0. It is still recognized.

A dictionary mapping URIs to either None or an URI. The keys are the base URI of the foreign Sphinx documentation sets and can be local paths or HTTP URIs. The values indicate where the inventory file can be found: they can be None (at the same location as the base URI) or another local or HTTP URI.

New format for this config value

New in version 1.0.

A dictionary mapping unique identifiers to a tuple (target, inventory). Each target is the base URI of a foreign Sphinx documentation set and can be a local path or an HTTP URI. The inventory indicates where the inventory file can be found: it can be None (at the same location as the base URI) or another local or HTTP URI.

The unique identifier can be used to prefix cross-reference targets, so that it is clear which intersphinx set the target belongs to. A link like :ref:comparison manual <python:comparisons> will link to the label “comparisons” in the doc set “python”, if it exists.

Example

To add links to modules and objects in the Python standard library documentation, use:

intersphinx_mapping = {'python': ('https://docs.python.org/3', None)}


This will download the corresponding objects.inv file from the Internet and generate links to the pages under the given URI. The downloaded inventory is cached in the Sphinx environment, so it must be re-downloaded whenever you do a full rebuild.

A second example, showing the meaning of a non-None value of the second tuple item:

intersphinx_mapping = {'python': ('https://docs.python.org/3',
'python-inv.txt')}


This will read the inventory from python-inv.txt in the source directory, but still generate links to the pages under https://docs.python.org/3. It is up to you to update the inventory file as new objects are added to the Python documentation.

Multiple target for the inventory

New in version 1.3.

Alternative files can be specified for each inventory. One can give a tuple for the second inventory tuple item as shown in the following example. This will read the inventory iterating through the (second) tuple items until the first successful fetch. The primary use case for this to specify mirror sites for server downtime of the primary inventory:

intersphinx_mapping = {'python': ('https://docs.python.org/3',
(None, 'python-inv.txt'))}

intersphinx_cache_limit

The maximum number of days to cache remote inventories. The default is 5, meaning five days. Set this to a negative value to cache inventories for unlimited time.

intersphinx_timeout

The number of seconds for timeout. The default is None, meaning do not timeout.

Note

timeout is not a time limit on the entire response download; rather, an exception is raised if the server has not issued a response for timeout seconds.

## Using Intersphinx with inventory file under Basic Authorization¶

Intersphinx supports Basic Authorization like this:

intersphinx_mapping = {'python': ('https://user:password@docs.python.org/3',
None)}


The user and password will be stripped from the URL when generating the links.