From 1b6e67dba6da0f7479484fd710cc53264cd784fa Mon Sep 17 00:00:00 2001
From: Alexey Skobkin <skobkin-ru@ya.ru>
Date: Sat, 19 Mar 2022 03:09:50 +0300
Subject: [PATCH 1/2] synapse-admin. Reconfiguring networks.

---
 synapse/docker-compose.yml | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/synapse/docker-compose.yml b/synapse/docker-compose.yml
index 5f694ab..f73ff4e 100644
--- a/synapse/docker-compose.yml
+++ b/synapse/docker-compose.yml
@@ -1,13 +1,22 @@
 version: '3.7'
 
+networks:
+  # You need to create this network manually first!
+  synapse:
+    external: true
+
 services:
   synapse:
     # https://hub.docker.com/r/matrixdotorg/synapse
     # https://github.com/matrix-org/synapse/tree/master/docker
     image: "matrixdotorg/synapse:${IMAGE_VERSION:-latest}"
     container_name: synapse
-    # This way we'll be able to access PostgreSQL on local machine using 'localhost' when it's listening only locally.
-    network_mode: host
+    hostname: synapse
+    extra_hosts:
+      - 'host.docker.internal:host-gateway'
+    networks:
+      - default
+      - synapse
     ports:
       - "${INTERFACE_EXT:-127.0.0.1}:${HTTP_PORT_EXT:-8008}:${HTTP_PORT_INT:-8008}/tcp"
     volumes:
-- 
2.40.1


From 02a3a7d8c1ffd08043da1ff01f474029f1462d42 Mon Sep 17 00:00:00 2001
From: Alexey Skobkin <skobkin-ru@ya.ru>
Date: Sat, 19 Mar 2022 04:11:41 +0300
Subject: [PATCH 2/2] Documentation regarding using the database running on the
 host machine.

---
 README.md                                    |  5 +++
 _docs/access_database_on_host_from_docker.md | 37 ++++++++++++++++++++
 synapse/README.md                            |  5 ++-
 3 files changed, 46 insertions(+), 1 deletion(-)
 create mode 100644 _docs/access_database_on_host_from_docker.md

diff --git a/README.md b/README.md
index 5f36c51..7d11915 100644
--- a/README.md
+++ b/README.md
@@ -21,6 +21,11 @@ docker-compose logs -f
 Some services may require additional configuration. Check for additional `README.md` files
 or comments in the `docker-compose.yml` files or `.env.dist` templates.
 
+## Using a database server on the host from the container
+
+You need to change your database configuration to be able to do that. Check 
+[this](_docs/access_database_on_host_from_docker.md) documentation.
+
 ## Is it working?
 
 Not every stack is tested to fully work.
diff --git a/_docs/access_database_on_host_from_docker.md b/_docs/access_database_on_host_from_docker.md
new file mode 100644
index 0000000..af90f1c
--- /dev/null
+++ b/_docs/access_database_on_host_from_docker.md
@@ -0,0 +1,37 @@
+# Using database on host machine from Docker
+
+
+## Database configuration
+
+### PostgreSQL
+You need to make PostgreSQL listen not only `localhost`, but also Docker's network interface.
+
+To do that you need to add host machine IP address in the Docker network (usually `172.17.0.1`) to the `postgresql.conf`:
+```ini
+# Listen local interface and also Docker's network
+listen_addresses = 'localhost,172.17.0.1'
+```
+
+Then you need to allow apps inside Docker containers to authenticate. That could be done in the `pg_hba.conf`:
+```
+# Docker network
+host    all             all             172.17.0.0/12            md5
+```
+
+Do not forget to restart your PostgreSQL server. For PostgreSQL 12 it could be usually done like that:
+
+```shell
+systemctl restart postgresql@12-main.service
+```
+
+### MySQL / MariaDB
+
+TBW
+
+## Application configuration inside Docker
+
+Stacks which allow to use external database back-end should also map `host.docker.internal` to the host machine
+address inside Docker's default network.
+
+So to connect to the database from the application inside the container you should use `host.docker.internal` as the
+database host/address.
diff --git a/synapse/README.md b/synapse/README.md
index 25ccd4a..fc35d89 100644
--- a/synapse/README.md
+++ b/synapse/README.md
@@ -10,7 +10,10 @@ docker-compose run synapse generate
 
 After that you can edit `./data/homeserver.yaml` according to your needs.
 
-If you want to use full-fledged PostgreSQL instead of SQLite, you can check [this documentation](https://github.com/matrix-org/synapse/blob/master/docs/postgres.md).
+If you want to use full-fledged PostgreSQL instead of SQLite, you can check
+[this documentation](https://github.com/matrix-org/synapse/blob/master/docs/postgres.md).
+
+To use PostgreSQL running on the host machine, use [this](../_docs/access_database_on_host_from_docker.md) configuration.
 
 # Running the server
 
-- 
2.40.1