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1# Mosquitto {#module-services-mosquitto}
2
3Mosquitto is a MQTT broker often used for IoT or home automation data transport.
4
5## Quickstart {#module-services-mosquitto-quickstart}
6
7A minimal configuration for Mosquitto is
8
9```nix
10{
11 services.mosquitto = {
12 enable = true;
13 listeners = [ {
14 acl = [ "pattern readwrite #" ];
15 omitPasswordAuth = true;
16 settings.allow_anonymous = true;
17 } ];
18 };
19}
20```
21
22This will start a broker on port 1883, listening on all interfaces of the machine, allowing
23read/write access to all topics to any user without password requirements.
24
25User authentication can be configured with the `users` key of listeners. A config that gives
26full read access to a user `monitor` and restricted write access to a user `service` could look
27like
28
29```nix
30{
31 services.mosquitto = {
32 enable = true;
33 listeners = [ {
34 users = {
35 monitor = {
36 acl = [ "read #" ];
37 password = "monitor";
38 };
39 service = {
40 acl = [ "write service/#" ];
41 password = "service";
42 };
43 };
44 } ];
45 };
46}
47```
48
49TLS authentication is configured by setting TLS-related options of the listener:
50
51```nix
52{
53 services.mosquitto = {
54 enable = true;
55 listeners = [ {
56 port = 8883; # port change is not required, but helpful to avoid mistakes
57 # ...
58 settings = {
59 cafile = "/path/to/mqtt.ca.pem";
60 certfile = "/path/to/mqtt.pem";
61 keyfile = "/path/to/mqtt.key";
62 };
63 } ];
64 };
65}
66```
67
68## Configuration {#module-services-mosquitto-config}
69
70The Mosquitto configuration has four distinct types of settings:
71the global settings of the daemon, listeners, plugins, and bridges.
72Bridges and listeners are part of the global configuration, plugins are part of listeners.
73Users of the broker are configured as parts of listeners rather than globally, allowing
74configurations in which a given user is only allowed to log in to the broker using specific
75listeners (eg to configure an admin user with full access to all topics, but restricted to
76localhost).
77
78Almost all options of Mosquitto are available for configuration at their appropriate levels, some
79as NixOS options written in camel case, the remainders under `settings` with their exact names in
80the Mosquitto config file. The exceptions are `acl_file` (which is always set according to the
81`acl` attributes of a listener and its users) and `per_listener_settings` (which is always set to
82`true`).
83
84### Password authentication {#module-services-mosquitto-config-passwords}
85
86Mosquitto can be run in two modes, with a password file or without. Each listener has its own
87password file, and different listeners may use different password files. Password file generation
88can be disabled by setting `omitPasswordAuth = true` for a listener; in this case it is necessary
89to either set `settings.allow_anonymous = true` to allow all logins, or to configure other
90authentication methods like TLS client certificates with `settings.use_identity_as_username = true`.
91
92The default is to generate a password file for each listener from the users configured to that
93listener. Users with no configured password will not be added to the password file and thus
94will not be able to use the broker.
95
96### ACL format {#module-services-mosquitto-config-acl}
97
98Every listener has a Mosquitto `acl_file` attached to it. This ACL is configured via two
99attributes of the config:
100
101 * the `acl` attribute of the listener configures pattern ACL entries and topic ACL entries
102 for anonymous users. Each entry must be prefixed with `pattern` or `topic` to distinguish
103 between these two cases.
104 * the `acl` attribute of every user configures in the listener configured the ACL for that
105 given user. Only topic ACLs are supported by Mosquitto in this setting, so no prefix is
106 required or allowed.
107
108The default ACL for a listener is empty, disallowing all accesses from all clients. To configure
109a completely open ACL, set `acl = [ "pattern readwrite #" ]` in the listener.