README.md

@@ -736,8 +736,14 @@ credentials.
 [upaas](https://git.eeqj.de/sneak/upaas) builds the image from this
 repository's `Dockerfile` and runs it. The app needs:
 
-- **Port:** container port `8080`. Leave `PORT` unset: the image's
-  health check probes `8080`.
+- **Network and port:** add no port mapping in upaas. upaas publishes
+  every mapped port on all interfaces of the host
+  ([upaas issue 113](https://git.eeqj.de/sneak/upaas/issues/113)),
+  which would put the plain-HTTP admin UI and receiver there. Instead,
+  set the app's Docker Network in upaas to your reverse proxy's Docker
+  network; the proxy then reaches the app at `upaas-` followed by the
+  app name, port `8080`. Leave `PORT` unset: the image's health check
+  probes `8080`.
 - **Volume:** one host directory mounted at `/var/lib/webhooker`.
   upaas bind-mounts the host path it is given and does not create it,
   and the container does not start unless UID 1000 owns it (see
@@ -752,10 +758,10 @@ repository's `Dockerfile` and runs it. The app needs:
 
 - **Environment variables:**
     - `WEBHOOKER_ENVIRONMENT=prod`
-    - `TRUSTED_PROXIES`: the address your reverse proxy connects from,
-      as the container sees it; the `remoteIP` field of each
-      `http request` log line shows it. See
-      [Trusted proxies](#trusted-proxies).
+    - `TRUSTED_PROXIES`: your reverse proxy's address on that Docker
+      network. The `remoteIP` field of the `http request` log line for a
+      request that came through the proxy shows it; the health check's
+      own lines show `::1`. See [Trusted proxies](#trusted-proxies).
     - Leave `BIND_ADDRESS` and `DATA_DIR` unset: the image sets
       `BIND_ADDRESS` to `0.0.0.0`, and `DATA_DIR` defaults to
       `/var/lib/webhooker`.