http://chriskief.com/2014/05/14/django-haystack-and-elasticsearch-part-1/

config.py

# add to installed apps
INSTALLED_APPS = (
    ...
    'haystack',
    ...
)

# haystack search using elasticsearch
HAYSTACK_CONNECTIONS = {
    'default': {
        'ENGINE': 'haystack.backends.elasticsearch_backend.ElasticsearchSearchEngine',
        'URL': 'http://127.0.0.1:9200/',
        'INDEX_NAME': 'haystack',
    },
}

# http://django-haystack.readthedocs.org/en/latest/signal_processors.html
HAYSTACK_SIGNAL_PROCESSOR = 'haystack.signals.RealtimeSignalProcessor'

# increase the default number of results (from 20)
HAYSTACK_SEARCH_RESULTS_PER_PAGE = 40