This module allows to split Drupal's url aliases into different contexts that allow to use the same alias for different source paths. The most prominent use case is a setup with different domains, where the same path is supposed to point to a different node, depending on the current domain.

http://a.com/imprint -> /node/1
http://b.com/imprint -> /node/2
http://c.com/imprint -> /node/3

Disclaimer: This is an advanced module that requires coding and knowledge about cache configuration.

When saving a new alias, the module will search for services tagged with alias_context_resolver that implement the AliasContextResolverInterface, and use them to determine the context for a given path.

/node/1 -> a
/node/2 -> b
/node/3 -> NULL

It will store this path and use it for resolving paths from aliases and vice versa. There it will consult the context resolver again to obtain the current context (e.g. the domain the request was sent to). If the result matches the stored context for this alias, it will behave normal. If not, aliases will prefixed (both ways) with their context. Non-contextual aliases remain functional, but will be picked with a lower priority.

/node/1 -> /a/imprint
/node/2 -> /b/imprint
/node/3 -> /imprint

/imprint -> /node/3

/node/1 -> /imprint
/node/2 -> /b/imprint
/node/3 -> /imprint

/imprint -> /node/1

current context: b

/node/1 -> /a/imprint
/node/2 -> /imprint
/node/3 -> /imprint

/imprint -> /node/2

The module requires you to implement your own context resolvers and add them as services tagged with alias_context_resolver and (more importantly) configure caching in a way it also respects the same contextual information. Otherwise you will have a very bad time watching your page cache serving random pages.