You do not need very tightly integrate intranet site mattermost . It is necessary that the users do not have to enter login \ password several times (or log in through a service) How best to do this?
Now I have done the following:
1. All Members of the site database moved (via IPA) in mattermost .
2. The database mattertost replaced them hash of the password hash from the database of the site (but the ugliness of that podelaesh passwords I do not know 
)
3 ...
After step 2, users can mattertost comes in with their usual username and password.
But to do that would mattermost learned my users at once? (Assuming that they are logged in)