Add the ability to update user passwords with ansible (when using the matrix-postgres container).

docs/README.md

@@ -12,6 +12,8 @@
 
 - [Registering users](registering-users.md)
 
+- [Updating users passwords](updating-users-passwords.md)
+
 - [Configuring service discovery via .well-known](configuring-well-known.md)
 
 - [Maintenance / checking if services work](maintenance-checking-services.md)

docs/updating-users-passwords.md

@@ -0,0 +1,19 @@
+# Updating users passwords
+
+If you are using the matrix-postgres container(default), you can do it via this Ansible playbook (make sure to edit the `<your-username>` and `<your-password>` part below):
+
+	ansible-playbook -i inventory/hosts setup.yml --extra-vars='username=<your-username> password=<your-password>' --tags=update-user-password
+
+**Note**: `<your-username>` is just a plain username (like `john`), not your full `@<username>:<your-domain>` identifier.
+
+**You can then log in with that user** via the riot-web service that this playbook has created for you at a URL like this: `https://riot.<domain>/`.
+
+If you are NOT using the matrix-postgres container, you can generate the password hash by using the command-line after **SSH**-ing to your server (requires that [all services have been started](#starting-the-services)):
+
+	docker exec -it matrix-synapse /usr/local/bin/hash_password -c /data/homeserver.yaml
+
+and then connecting to the postgres server and executing:
+
+	UPDATE users SET password_hash = '<password-hash>' WHERE name = '@someone:server.com'
+
+where `<password-hash>` is the hash returned by the docker command above.