Pulp

Are you sure this is a real issue? The HREF you're providing is the base repository endpoint, not a specific repository. I wouldn't expect that to work...

edit: I tested it, and I see what you're saying

[vagrant@pulp3 ~]$ echo $REPO_HREF 
http://localhost:8000/api/v3/repositories/e7bd294f-4a5f-45ec-a582-534a8f029055/

[vagrant@pulp3 ~]$ http POST $REMOTE_HREF'sync/' repository=http://pulp3:8000/api/v3/repositories/e7bd294f-4a5f-45ec-a582-534a8f029055/
HTTP/1.1 400 Bad Request
Allow: POST, OPTIONS
Content-Type: application/json
Date: Sun, 15 Apr 2018 04:13:09 GMT
Server: WSGIServer/0.2 CPython/3.6.2
Vary: Accept

{
    "repository": [
        "Enter a valid URL."
    ]
}

Although I don't understand why specifying a non-repository is considered valid. It probably works ONLY because there is only one repository in existence during testing.

[vagrant@pulp3 ~]$ http POST $REMOTE_HREF'sync/' repository=http://localhost:8000/api/v3/repositories/
HTTP/1.1 202 Accepted
Allow: POST, OPTIONS
Content-Type: application/json
Date: Sun, 15 Apr 2018 04:15:28 GMT
Server: WSGIServer/0.2 CPython/3.6.2
Vary: Accept

[
    {
        "_href": "http://localhost:8000/api/v3/tasks/c4ddafe1-7f3f-4695-9557-5ae96c8ce59e/",
        "task_id": "c4ddafe1-7f3f-4695-9557-5ae96c8ce59e"
    }
]

edit: It totally blows up if you have 2 repositories

Internal Server Error: /api/v3/remotes/file/24ce2926-c3a5-43b1-85d9-e01408c54568/sync/                                                      
Traceback (most recent call last): 
  File "/home/vagrant/.virtualenvs/pulp/lib64/python3.6/site-packages/django/core/handlers/exception.py", line 35, in inner                 
    response = get_response(request)                                  
  File "/home/vagrant/.virtualenvs/pulp/lib64/python3.6/site-packages/django/core/handlers/base.py", line 128, in _get_response             
    response = self.process_exception_by_middleware(e, request)       
  File "/home/vagrant/.virtualenvs/pulp/lib64/python3.6/site-packages/django/core/handlers/base.py", line 126, in _get_response             
    response = wrapped_callback(request, *callback_args, **callback_kwargs)                                                                 
  File "/home/vagrant/.virtualenvs/pulp/lib64/python3.6/site-packages/django/views/decorators/csrf.py", line 54, in wrapped_view            
    return view_func(*args, **kwargs)                                 
  File "/home/vagrant/.virtualenvs/pulp/lib64/python3.6/site-packages/rest_framework/viewsets.py", line 103, in view                        
    return self.dispatch(request, *args, **kwargs)                    
  File "/home/vagrant/.virtualenvs/pulp/lib64/python3.6/site-packages/rest_framework/views.py", line 483, in dispatch                       
    response = self.handle_exception(exc)                             
  File "/home/vagrant/.virtualenvs/pulp/lib64/python3.6/site-packages/rest_framework/views.py", line 443, in handle_exception                   self.raise_uncaught_exception(exc)                                
  File "/home/vagrant/.virtualenvs/pulp/lib64/python3.6/site-packages/rest_framework/views.py", line 480, in dispatch                           response = handler(request, *args, **kwargs)                      
  File "/home/vagrant/devel/pulp_file/pulp_file/app/viewsets.py", line 104, in sync                                                             repository = self.get_resource(repository_uri, Repository)        
  File "/home/vagrant/devel/pulp/pulpcore/pulpcore/app/viewsets/base.py", line 136, in get_resource                                             return model.objects.get(**kwargs)                                
  File "/home/vagrant/.virtualenvs/pulp/lib64/python3.6/site-packages/django/db/models/manager.py", line 82, in manager_method              
    return getattr(self.get_queryset(), name)(*args, **kwargs)        
  File "/home/vagrant/.virtualenvs/pulp/lib64/python3.6/site-packages/django/db/models/query.py", line 407, in get                          
    (self.model._meta.object_name, num)                               
pulpcore.app.models.repository.MultipleObjectsReturned: get() returned more than one Repository -- it returned 2!     

This is a separate issue though. I'll file it. edit: https://pulp.plan.io/issues/3567

I encountered a similar error, but I have a dot in my hostname:

~/3/devel ❯ http POST http://dev.pulp3:8000/api/v3/remotes/file/46c27193-16a8-4111-96be-c14af9016170/sync/ repository=http://dev.pulp3:8000/api/v3/repositories/2ad9c51b-f7af-4cfe-a978-523f1b54c6f2/      3.0-dev

HTTP/1.0 400 Bad Request
Allow: POST, OPTIONS
Content-Length: 37
Content-Type: application/json
Date: Thu, 19 Apr 2018 14:25:05 GMT
Server: WSGIServer/0.2 CPython/3.6.4
Vary: Accept, Cookie
X-Frame-Options: SAMEORIGIN

{
    "repository": [
        "Enter a valid URL."
    ]
}