diff --git a/.github/workflows/go.yml b/.github/workflows/go.yml
index 8d46488..c98914c 100644
--- a/.github/workflows/go.yml
+++ b/.github/workflows/go.yml
@@ -1,5 +1,5 @@
 name: ci
-on: [push]
+on: [push, pull_request]
 jobs:
 
   build:
diff --git a/src/gossa.go b/src/gossa.go
index e1e078f..f4d1904 100755
--- a/src/gossa.go
+++ b/src/gossa.go
@@ -68,6 +68,7 @@ func hash(s string) string {
 func exitPath(w http.ResponseWriter, s ...interface{}) {
 	if r := recover(); r != nil {
 		log.Println("error", s, r)
+		w.WriteHeader(500)
 		w.Write([]byte("error"))
 	} else if *verb {
 		log.Println(s...)
diff --git a/support/build.Dockerfile b/support/build.Dockerfile
index dc1f21c..de6f990 100644
--- a/support/build.Dockerfile
+++ b/support/build.Dockerfile
@@ -3,6 +3,9 @@ COPY . /gossaSrc
 RUN cd /gossaSrc && make
 
 FROM alpine
+ENV UID="1000" GID="1000" HOST="0.0.0.0" PORT="8001" PREFIX="/" FOLLOW_SYMLINKS="false" SKIP_HIDDEN_FILES="true" DATADIR="/shared"
 EXPOSE 8001
+RUN apk add --no-cache su-exec
 COPY --from=builder /gossaSrc/gossa /gossa
-ENTRYPOINT [ "/gossa", "-h", "0.0.0.0", "/shared" ]
+RUN echo -e 'exec su-exec ${UID}:${GID} /gossa -h ${HOST} -p ${PORT} -k=${SKIP_HIDDEN_FILES} --symlinks=${FOLLOW_SYMLINKS} --prefix=${PREFIX} ${DATADIR}'>> /start.sh
+ENTRYPOINT [ "sh", "/start.sh" ]
diff --git a/support/readme.md b/support/readme.md
index 1fcee4e..d77bbb3 100644
--- a/support/readme.md
+++ b/support/readme.md
@@ -15,6 +15,7 @@ if you prefer building the image yourself :
 % sudo docker run -v ~/LocalDirToShare:/shared -p 8001:8001 gossa
 ```
 
+the options are settable through environment variables that can be passed starting off the docker image.
 
 a fancy docker image using [Caddy](https://caddyserver.com/) is also provided. a simple config is embedded in the docker file, and shows how to use http basic authentication, and automatic TLS for hands-free https 🎉