From 703149d76d2e663ff4222e92f8a13becc304a3ca Mon Sep 17 00:00:00 2001
From: Richard van der Hoff <1389908+richvdh@users.noreply.github.com>
Date: Fri, 3 Jan 2025 11:46:12 +0000
Subject: [PATCH] Docker: allow configuration of HTTP listen port via env var
 (#28840)

* Docker: allow configuration of HTTP listen port via env var

* Update docs/install.md

Co-authored-by: Michael Telatynski <7t3chguy@gmail.com>

* prettier

---------

Co-authored-by: Michael Telatynski <7t3chguy@gmail.com>
---
 Dockerfile                                             |  8 ++++++--
 .../nginx-templates/default.conf.template              |  4 ++--
 docs/install.md                                        | 10 ++++++++++
 3 files changed, 18 insertions(+), 4 deletions(-)
 rename nginx/conf.d/default.conf => docker/nginx-templates/default.conf.template (90%)

diff --git a/Dockerfile b/Dockerfile
index d46924865c..3cab540bb7 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -21,8 +21,12 @@ FROM nginx:alpine-slim
 
 COPY --from=builder /src/webapp /app
 
-# Override default nginx config
-COPY /nginx/conf.d/default.conf /etc/nginx/conf.d/default.conf
+# Override default nginx config. Templates in `/etc/nginx/templates` are passed
+# through `envsubst` by the nginx docker image entry point.
+COPY /docker/nginx-templates/* /etc/nginx/templates/
 
 RUN rm -rf /usr/share/nginx/html \
   && ln -s /app /usr/share/nginx/html
+
+# HTTP listen port
+ENV ELEMENT_WEB_PORT=80
diff --git a/nginx/conf.d/default.conf b/docker/nginx-templates/default.conf.template
similarity index 90%
rename from nginx/conf.d/default.conf
rename to docker/nginx-templates/default.conf.template
index 0ae5790374..06f33e08dd 100644
--- a/nginx/conf.d/default.conf
+++ b/docker/nginx-templates/default.conf.template
@@ -1,6 +1,6 @@
 server {
-    listen       80;
-    listen  [::]:80;
+    listen       ${ELEMENT_WEB_PORT};
+    listen  [::]:${ELEMENT_WEB_PORT};
     server_name  localhost;
 
     root   /usr/share/nginx/html;
diff --git a/docs/install.md b/docs/install.md
index 1c182cdd34..7830324ffc 100644
--- a/docs/install.md
+++ b/docs/install.md
@@ -60,6 +60,16 @@ would be:
 docker run --rm -p 127.0.0.1:80:80 -v /etc/element-web/config.json:/app/config.json vectorim/element-web
 ```
 
+The behaviour of the docker image can be customised via the following
+environment variables:
+
+- `ELEMENT_WEB_PORT`
+
+    The port to listen on (within the docker container) for HTTP
+    traffic. Defaults to `80`.
+
+### Building the docker image
+
 To build the image yourself:
 
 ```bash