Add support for external-IP-address-autodetection to Coturn

Author: spantaleev

docs/configuring-playbook-turn.md

@@ -16,13 +16,24 @@ matrix_coturn_enabled: false
 In that case, Synapse would not point to any Coturn servers and audio/video call functionality may fail.
 
 ## Manually defining your public IP
+
 In the `hosts` file we explicitly ask for your server's external IP address when defining `ansible_host`, because the same value is used for configuring Coturn.
+
 If you'd rather use a local IP for `ansible_host`, make sure to set up `matrix_coturn_turn_external_ip_address` replacing `YOUR_PUBLIC_IP` with the pubic IP used by the server.
 
 ```yaml
 matrix_coturn_turn_external_ip_address: "YOUR_PUBLIC_IP"
 ```
 
+If you'd like to rely on external IP address auto-detection (not recommended unless you need it), set `matrix_coturn_turn_external_ip_address` to an empty value. The playbook will automatically contact an [EchoIP](https://github.com/mpolden/echoip)-compatible service (`https://ifconfig.co/json` by default) to determine your server's IP address. This API endpoint is configurable via the `matrix_coturn_turn_external_ip_address_auto_detection_echoip_service_url` variable.
+
+If your server has multiple external IP addresses, the Coturn role offers a different variable for specifying them:
+
+```yaml
+# Note: matrix_coturn_turn_external_ip_addresses is different than matrix_coturn_turn_external_ip_address
+matrix_coturn_turn_external_ip_addresses: ['1.2.3.4', '4.5.6.7']
+```
+
 ## Using your own external Coturn server
 
 If you'd like to use another TURN server (be it Coturn or some other one), you can configure the playbook like this:
@@ -49,4 +60,4 @@ jitsi_web_stun_servers:
 You can put multiple host/port combinations if you like.
 
 ## Further variables and configuration options
-To see all the available configuration options, check roles/custom/matrix-coturn/defaults/main.yml 
+To see all the available configuration options, check roles/custom/matrix-coturn/defaults/main.yml

examples/vars.yml

@@ -41,3 +41,19 @@ devture_traefik_config_certificatesResolvers_acme_email: ''
 # The playbook creates additional Postgres users and databases (one for each enabled service)
 # using this superuser account.
 devture_postgres_connection_password: ''
+
+# By default, we configure Coturn's external IP address using the value specified for `ansible_host` in your `inventory/hosts` file.
+# If this value is an external IP address, you can skip this section.
+#
+# If `ansible_host` is not the server's external IP address, you have 2 choices:
+# 1. Uncomment the line below, to allow IP address auto-detection to happen (more on this below)
+# 2. Uncomment and adjust the line below to specify an IP address manually
+#
+# By default, auto-detection will be attempted using the `https://ifconfig.co/json` API.
+# Default values for this are specified in `matrix_coturn_turn_external_ip_address_auto_detection_*` variables in the Coturn role
+# (see `roles/custom/matrix-coturn/defaults/main.yml`).
+#
+# If your server has multiple IP addresses, you may define them in another variable which allows a list of addresses.
+# Example: `matrix_coturn_turn_external_ip_addresses: ['1.2.3.4', '4.5.6.7']`
+#
+# matrix_coturn_turn_external_ip_address: ''

group_vars/matrix_servers

@@ -2245,6 +2245,9 @@ matrix_coturn_enabled: true
 
 matrix_coturn_container_image_self_build: "{{ matrix_architecture not in ['amd64', 'arm32', 'arm64'] }}"
 
+# We make the assumption that `ansible_host` points to an external IP address, which may not always be the case.
+# Users are free to set `matrix_coturn_turn_external_ip_address` to an empty string
+# to allow auto-detection (via an EchoIP service) to happen at runtime.
 matrix_coturn_turn_external_ip_address: "{{ ansible_host }}"
 
 matrix_coturn_turn_static_auth_secret: "{{ '%s' | format(matrix_homeserver_generic_secret_key) | password_hash('sha512', 'coturn.sas', rounds=655555) | to_uuid }}"

roles/custom/matrix-coturn/defaults/main.yml

@@ -73,8 +73,25 @@ matrix_coturn_turn_udp_max_port: 49172
 matrix_coturn_turn_static_auth_secret: ""
 
 # The external IP address of the machine where Coturn is.
+# If do not define an IP address here or in `matrix_coturn_turn_external_ip_addresses`, auto-detection via an EchoIP service will be done.
+# See `matrix_coturn_turn_external_ip_address_auto_detection_enabled`
 matrix_coturn_turn_external_ip_address: ''
-matrix_coturn_turn_external_ip_addresses: ["{{ matrix_coturn_turn_external_ip_address }}"]
+matrix_coturn_turn_external_ip_addresses: "{{ [matrix_coturn_turn_external_ip_address] if matrix_coturn_turn_external_ip_address != '' else [] }}"
+
+# Controls whether external IP address auto-detection should be attempted.
+# We try to do this if there is no external IP address explicitly configured and if an EchoIP service URL is specified.
+# See matrix_coturn_turn_external_ip_address_auto_detection_echoip_service_url
+matrix_coturn_turn_external_ip_address_auto_detection_enabled: "{{ matrix_coturn_turn_external_ip_addresses | length == 0 and matrix_coturn_turn_external_ip_address_auto_detection_echoip_service_url != '' }}"
+
+# Specifies the address of the EchoIP service (https://github.com/mpolden/echoip) to use for detecting the external IP address.
+# By default, we use the official public instance.
+matrix_coturn_turn_external_ip_address_auto_detection_echoip_service_url: https://ifconfig.co/json
+
+# Controls whether SSL certificates will be validated when contacting the EchoIP service (matrix_coturn_turn_external_ip_address_auto_detection_echoip_service_url)
+matrix_coturn_turn_external_ip_address_auto_detection_echoip_validate_certs: true
+
+matrix_coturn_turn_external_ip_address_auto_detection_echoip_service_retries_count: "{{ devture_playbook_help_geturl_retries_count }}"
+matrix_coturn_turn_external_ip_address_auto_detection_echoip_service_retries_delay: "{{ devture_playbook_help_geturl_retries_delay }}"
 
 matrix_coturn_allowed_peer_ips: []
 

roles/custom/matrix-coturn/tasks/setup_install.yml

@@ -1,5 +1,37 @@
 ---
 
+- when: matrix_coturn_turn_external_ip_address_auto_detection_enabled | bool
+  block:
+    - when: matrix_coturn_turn_external_ip_address_auto_detection_echoip_service_url == ''
+      name: Fail if enabled, but EchoIP service URL unset
+      ansible.builtin.fail:
+        msg: "To use the external IP address auto-detection feature, you need to set matrix_coturn_turn_external_ip_address_auto_detection_echoip_service_url"
+
+    # NOTE:
+    # `ansible.builtin.uri` does not provide a way to configure whether IPv4 or IPv6 is used.
+    # Luckily, the default instance we use does not define AAAA records for now, so it's always IPv4.
+    - name: Fetch IP address information from EchoIP service
+      ansible.builtin.uri:
+        url: "{{ matrix_coturn_turn_external_ip_address_auto_detection_echoip_service_url }}"
+        headers:
+          Content-Type: application/json
+        follow_redirects: none
+        validate_certs: "{{ matrix_coturn_turn_external_ip_address_auto_detection_echoip_validate_certs }}"
+      register: result_matrix_coturn_turn_external_ip_address_auto_detection_echoip_response
+      ignore_errors: true
+      check_mode: false
+      retries: "{{ matrix_coturn_turn_external_ip_address_auto_detection_echoip_service_retries_count }}"
+      delay: "{{ matrix_coturn_turn_external_ip_address_auto_detection_echoip_service_retries_delay }}"
+      until: not result_matrix_coturn_turn_external_ip_address_auto_detection_echoip_response.failed
+
+    - when: "(result_matrix_coturn_turn_external_ip_address_auto_detection_echoip_response.failed or 'json' not in result_matrix_coturn_turn_external_ip_address_auto_detection_echoip_response)"
+      name: Fail if EchoIP service failed
+      ansible.builtin.fail:
+        msg: "Failed contacting EchoIP service API at `{{ matrix_coturn_turn_external_ip_address_auto_detection_echoip_service_url }}` (controlled by `matrix_coturn_turn_external_ip_address_auto_detection_echoip_service_url`). Full error: {{ result_matrix_coturn_turn_external_ip_address_auto_detection_echoip_response }}"
+
+    - ansible.builtin.set_fact:
+        matrix_coturn_turn_external_ip_address: "{{ result_matrix_coturn_turn_external_ip_address_auto_detection_echoip_response.json.ip }}"
+
 - name: Ensure Matrix Coturn path exists
   ansible.builtin.file:
     path: "{{ item.path }}"

roles/custom/matrix-coturn/templates/turnserver.conf.j2

@@ -5,7 +5,7 @@ realm=turn.{{ matrix_server_fqn_matrix }}
 
 min-port={{ matrix_coturn_turn_udp_min_port }}
 max-port={{ matrix_coturn_turn_udp_max_port }}
-{% for ip in matrix_coturn_turn_external_ip_addresses|select('ne', '') %}
+{% for ip in matrix_coturn_turn_external_ip_addresses %}
 external-ip={{ ip }}
 {% endfor %}