diff --git a/.github/workflows/build-weekly-all.yml b/.github/workflows/build-weekly-all.yml
index 15b2cfb..839d9de 100644
--- a/.github/workflows/build-weekly-all.yml
+++ b/.github/workflows/build-weekly-all.yml
@@ -37,7 +37,7 @@ jobs:
       -
         name: Set up Docker Buildx
         id: buildx
-        uses: docker/setup-buildx-action@v1.5.1
+        uses: docker/setup-buildx-action@v1.6.0
       -
         name: Available platforms
         run: echo ${{ steps.buildx.outputs.platforms }}
diff --git a/CHANGELOG.md b/CHANGELOG.md
new file mode 100644
index 0000000..f57b016
--- /dev/null
+++ b/CHANGELOG.md
@@ -0,0 +1,14 @@
+# Changelog
+
+## 0.3.0
+
+- Base image updated to Debian 11 (Bullseye)
+- RELEASE not hardcoded anymore. Now configurable via environment variable.
+
+## 0.2.0
+
+- build improved
+
+## 0.1.1
+
+- initial release
diff --git a/Dockerfile b/Dockerfile
index 46b96bd..76b5adf 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,4 +1,4 @@
-FROM	debian:10-slim as build
+FROM	debian:11-slim as build
 
 ENV	PACKAGES="apache2 reprepro"
 
diff --git a/README.md b/README.md
index 3cf4909..84124c6 100644
--- a/README.md
+++ b/README.md
@@ -16,14 +16,14 @@ Docker image for running a Debian repositority based on [this](https://wiki.debi
 ## Run repository demo
 
     # Passphrase for GPG key: insecure
-    docker run --rm -it -p 80:80 -v $PWD/repo-demo:/mnt:ro casperklein/debian-repo
+    docker run --rm -it -p 80:80 -v $PWD/repo-demo:/mnt:ro -e RELEASE=bullseye casperklein/debian-repo
 
-## Setup repository on client:
+## Setup repository on a client
 
 Import repository public key
 
     wget -O - http://HOSTNAME/repos/apt/debian/repo.gpg | apt-key add -
-    
+
 Add repository to apt sources
 
     echo "deb http://HOSTNAME/repos/apt/debian/ $(lsb_release -cs) main" >> /etc/apt/sources.list
@@ -31,28 +31,26 @@ Add repository to apt sources
 ## Create own repository
 
 1. Copy repo-demo
-    
-    ``cp -a repo-demo myrepo``
+
+    `cp -a repo-demo myrepo`
 
 1. Create/Export new GPG key
 
-    ``gpg --gen-key``
+    `gpg --gen-key`
 
-    ``gpg -a -o myrepo/key.gpg --export-secret-keys <ID>``
+    `gpg -a -o myrepo/key.gpg --export-secret-keys <ID>`
 
 1. Edit *myrepo/distributions* to your needs
 
     At least, you have to set *SignWith* to your GPG subkey ID
 
-    ``gpg --fingerprint --fingerprint # show subkey ID (remove spaces)``
-
-    or
+    `gpg --list-secret-key --with-subkey-fingerprint # show subkey ID`
 
-    ``gpg --edit-key <ID> quit``
+    If you change "Codename", you have to adjust `-e RELEASE=` below accordingly.
 
 1. Run own repository
 
-    ``docker run --rm -it -p 80:80 -v $PWD/myrepo:/mnt:ro casperklein/debian-repo``
+    `docker run --rm -it -p 80:80 -v $PWD/myrepo:/mnt:ro -e RELEASE=bullseye casperklein/debian-repo`
 
 [aarch64-shield]: https://img.shields.io/badge/aarch64-yes-blue.svg
 [amd64-shield]: https://img.shields.io/badge/amd64-yes-blue.svg
diff --git a/config.json b/config.json
index 7cc7e73..15a4b7e 100644
--- a/config.json
+++ b/config.json
@@ -2,5 +2,5 @@
   "user": "casperklein",
   "name": "debian-repo",
   "image": "casperklein/debian-repo",
-  "version": "0.2.0"
+  "version": "0.3.0"
 }
diff --git a/repo-demo/distributions b/repo-demo/distributions
index a9d1393..59f137e 100644
--- a/repo-demo/distributions
+++ b/repo-demo/distributions
@@ -1,6 +1,6 @@
 Origin: Repo Demo
 Label: Repo Demo
-Codename: buster
+Codename: bullseye
 Architectures: amd64
 Components: main
 Description: Apt repository with a dummy package
diff --git a/rootfs/run.sh b/rootfs/run.sh
index 05ab2af..b3d7680 100755
--- a/rootfs/run.sh
+++ b/rootfs/run.sh
@@ -1,5 +1,11 @@
 #!/bin/bash
 
+if [ -z "$RELEASE" ]; then
+	echo "Error: RELEASE not set."
+	echo
+	exit 1
+fi >&2
+
 set -ueo pipefail
 
 # import gpg key
@@ -14,13 +20,13 @@ cp /mnt/distributions conf/
 gpg -a --export -o repo.gpg
 
 # import packages
-reprepro includedeb buster /mnt/*.deb
+reprepro includedeb "$RELEASE" /mnt/*.deb
 kill $(pidof gpg-agent)
 echo
 echo
 
 echo 'Serving packages:'
-reprepro list buster
+reprepro list "$RELEASE"
 echo
 echo