Docker: pass DONATION_ADDRESS to the server, document it

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

.env.example

@@ -4,6 +4,8 @@ PLM_RPC_USER=username
 PLM_RPC_PASSWORD=change-me
 #CACHE_MB=1200
 #REPORT_SERVICES=tcp://electrum.example.com:50001
+# address for donations, sent to the clients; not checked by the server, so double-check it
+#DONATION_ADDRESS=
 #ELECTRUMX_TCP_PORT=50001
 
 # Data directory of the host: db/ (database) and ssl/ (certificate). Create it first: mkdir -p ~/.plm-electrumx/db ~/.plm-electrumx/ssl

DEPLOY.md

@@ -173,6 +173,22 @@ Peer discovery is on by default (`PEER_DISCOVERY`, `PEER_ANNOUNCE`). `lib/coins.
 servers you know there (format: `'host s t'`, for example `'electrum.example.com s50002 t50001'`) and rebuild, or
 keep the server private with `PEER_DISCOVERY=off` / `PEER_DISCOVERY=self`.
 
+## Donation address
+
+`DONATION_ADDRESS` in `.env` sets the address the server reports to its clients. It is optional and empty by default
+(no address).
+
+```ini
+DONATION_ADDRESS=plm1q...your address...
+```
+
+- Clients get it with the Electrum protocol call `server.donation_address`; wallets that support it show it to the user.
+- A banner file (`BANNER_FILE`, see `docs/environment.rst`) can contain the placeholder `$DONATION_ADDRESS`, which is
+  replaced with this address.
+- The server does **not** check the value, it only passes it on. Check it carefully (for example send a small test
+  amount) and use an address you are happy to make public, since it is sent to everyone who connects.
+- After changing it, apply it with `docker compose up -d` (the container is recreated with the new value).
+
 ## Data directory and first start
 
 Create the data directory as the user that runs Docker, before the first start (otherwise Docker creates it as root and

docker-compose.yml

@@ -11,6 +11,8 @@ services:
       CACHE_MB: ${CACHE_MB:-1200}
       # address announced to other servers and clients, if this server is public (tcp://host:50001)
       REPORT_SERVICES: ${REPORT_SERVICES:-}
+      # donation address sent to the clients (server.donation_address); empty: none
+      DONATION_ADDRESS: ${DONATION_ADDRESS:-}
       # SSL: on by default, with a self-signed certificate generated on the first start (docker-entrypoint.sh)
       SSL_ENABLED: ${SSL_ENABLED:-true}
       SSL_HOSTNAME: ${SSL_HOSTNAME:-electrumx}