diff --git a/.env b/.env
index 37dbc67..5cbee27 100644
--- a/.env
+++ b/.env
@@ -1,8 +1,6 @@
 # don't forget to add the minus before the version
-# example: VERSION=-3.2.0-12
 IMAGE_REPO=zammad/zammad-docker-compose
-VERSION=-3.2.0-13
-RESTART=always
-POSTGRES_USER=zammad
 POSTGRES_PASS=zammad
-
+POSTGRES_USER=zammad
+RESTART=always
+VERSION=-3.2.0-13
diff --git a/.github/lint-scripts.sh b/.github/lint-scripts.sh
index 194b74d..7bf2204 100755
--- a/.github/lint-scripts.sh
+++ b/.github/lint-scripts.sh
@@ -5,15 +5,9 @@
 
 set -o errexit
 
-CONFIG_DIR=".github"
-HOOKS_DIR="hooks"
-CONTAINER_DIR="containers"
-
 TMP_FILE="$(mktemp)"
 
-find "${CONFIG_DIR}" -type f -name "*.sh" > "${TMP_FILE}"
-find "${HOOKS_DIR}" -type f -name "*.sh" >> "${TMP_FILE}"
-find "${CONTAINER_DIR}" -type f -name "*.sh" >> "${TMP_FILE}"
+find . -type f -name "*.sh" > "${TMP_FILE}"
 
 while read -r FILE; do
   echo lint "${FILE}"
diff --git a/.github/tests.sh b/.github/tests.sh
new file mode 100755
index 0000000..5a2dbd3
--- /dev/null
+++ b/.github/tests.sh
@@ -0,0 +1,20 @@
+#!/bin/bash
+#
+# run zammad tests
+#
+
+set -o errexit
+set -o pipefail
+
+docker-compose logs --timestamps --follow &
+
+until (curl -I --silent --fail localhost | grep -iq "HTTP/1.1 200 OK"); do
+    echo "wait for zammad to be ready..."
+    sleep 15
+done
+
+sleep 10
+
+echo
+echo "Success - Zammad is up :)"
+echo
diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index 2ea4e55..2e7ae51 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -14,14 +14,37 @@ jobs:
         with:
           args: .github/lint-scripts.sh
 
-  install-docker-compose:
-    name: install-docker-compose
+  lint-docker-files:
     runs-on: ubuntu-latest
     needs: lint-bash-scripts
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v1    
+      - name: lint zammad dockerfile
+        uses: brpaz/hadolint-action@master
+        with:
+          dockerfile: containers/zammad-elasticsearch/Dockerfile
+      - name: lint elasticsearch dockerfile
+        uses: brpaz/hadolint-action@master
+        with:
+          dockerfile: containers/zammad-postgresql/Dockerfile
+      - name: lint postgresql dockerfile
+        uses: brpaz/hadolint-action@master
+        with:
+          dockerfile: containers/zammad/Dockerfile                    
+
+  test-docker-compose:
+    timeout-minutes: 30
+    runs-on: ubuntu-latest
+    needs: lint-docker-files
     steps:
       - name: Checkout
         uses: actions/checkout@v1
-      - name: get containers
+      - name: pull container images
         run: docker-compose pull
-      - name: install
-        run: docker-compose up
+      - name: run docker-compose up
+        run: docker-compose up --detach
+      - name: run tests
+        run: .github/tests.sh
+
+  
\ No newline at end of file
diff --git a/Dockerfile b/Dockerfile
index 7ea740b..b5001d1 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,4 +1,3 @@
-MAINTAINER Zammad <info@zammad.org>
 ARG BUILD_DATE
 
 LABEL org.label-schema.build-date="$BUILD_DATE" \
diff --git a/containers/zammad-elasticsearch/Dockerfile b/containers/zammad-elasticsearch/Dockerfile
index 3321a17..99f5e06 100644
--- a/containers/zammad-elasticsearch/Dockerfile
+++ b/containers/zammad-elasticsearch/Dockerfile
@@ -1,5 +1,4 @@
 FROM docker.elastic.co/elasticsearch/elasticsearch:7.6.0
-MAINTAINER Zammad <info@zammad.org>
 ARG BUILD_DATE
 
 LABEL org.label-schema.build-date="$BUILD_DATE" \
@@ -13,4 +12,6 @@ LABEL org.label-schema.build-date="$BUILD_DATE" \
       org.label-schema.schema-version="3.2.0" \
       org.label-schema.docker.cmd="sysctl -w vm.max_map_count=262144;docker-compose up"
 
+SHELL ["/bin/bash", "-e", "-o", "pipefail", "-c"]
+
 RUN yes | /usr/share/elasticsearch/bin/elasticsearch-plugin install ingest-attachment
diff --git a/containers/zammad-postgresql/Dockerfile b/containers/zammad-postgresql/Dockerfile
index d40260b..bacf81c 100644
--- a/containers/zammad-postgresql/Dockerfile
+++ b/containers/zammad-postgresql/Dockerfile
@@ -1,6 +1,5 @@
 FROM postgres:9.6.17-alpine
 
-MAINTAINER Zammad <info@zammad.org>
 ARG BUILD_DATE
 
 LABEL org.label-schema.build-date="$BUILD_DATE" \
@@ -14,6 +13,8 @@ LABEL org.label-schema.build-date="$BUILD_DATE" \
       org.label-schema.schema-version="3.2.0" \
       org.label-schema.docker.cmd="sysctl -w vm.max_map_count=262144;docker-compose up"
 
+SHELL ["/bin/bash", "-e", "-o", "pipefail", "-c"]
+
 # copy backup script
 COPY containers/zammad-postgresql/backup.sh /usr/local/bin/
 RUN chmod +x /usr/local/bin/backup.sh
diff --git a/containers/zammad-postgresql/backup.sh b/containers/zammad-postgresql/backup.sh
old mode 100644
new mode 100755
index 77793b5..6774d76
--- a/containers/zammad-postgresql/backup.sh
+++ b/containers/zammad-postgresql/backup.sh
@@ -33,7 +33,7 @@ function zammad_backup {
   fi
 
   #db backup
-  pg_dump --dbname=postgresql://"${POSTGRESQL_USER}:${POSTGRESQL_PASSWORD}"@"${POSTGRESQL_HOST}":"${POSTGRESQL_PORT}"/"${POSTGRESQL_DB}" | gzip > "${BACKUP_DIR}"/"${TIMESTAMP}"_zammad_db.psql.gz
+  pg_dump --dbname=postgresql://"${POSTGRESQL_USER}:${POSTGRESQL_PASSWORD}@${POSTGRESQL_HOST}:${POSTGRESQL_PORT}/${POSTGRESQL_DB}" | gzip > "${BACKUP_DIR}"/"${TIMESTAMP}"_zammad_db.psql.gz
 }
 
 if [ "$1" = 'zammad-backup' ]; then
diff --git a/containers/zammad/Dockerfile b/containers/zammad/Dockerfile
index 0403b77..8fb92f5 100644
--- a/containers/zammad/Dockerfile
+++ b/containers/zammad/Dockerfile
@@ -2,7 +2,6 @@ FROM ruby:2.5.5-slim AS builder
 # note: zammad is currently incompatible to alpine because of: 
 # https://github.com/docker-library/ruby/issues/113
 
-MAINTAINER Zammad <info@zammad.org>
 ARG BUILD_DATE
 ARG DEBIAN_FRONTEND=noninteractive
 
@@ -17,6 +16,8 @@ ENV ZAMMAD_READY_FILE ${ZAMMAD_DIR}/tmp/zammad.ready
 ENV ZAMMAD_TMP_DIR /tmp/zammad-${GIT_BRANCH}
 ENV ZAMMAD_USER zammad
 
+SHELL ["/bin/bash", "-e", "-o", "pipefail", "-c"]
+
 # install zammad
 COPY containers/zammad/setup.sh /tmp
 RUN chmod +x /tmp/setup.sh; \
@@ -25,7 +26,6 @@ RUN chmod +x /tmp/setup.sh; \
 
 FROM ruby:2.5.5-slim
 
-MAINTAINER Zammad <info@zammad.org>
 ARG BUILD_DATE
 ARG DEBIAN_FRONTEND=noninteractive
 
diff --git a/containers/zammad/setup.sh b/containers/zammad/setup.sh
old mode 100644
new mode 100755
index 8446462..822b8d8
--- a/containers/zammad/setup.sh
+++ b/containers/zammad/setup.sh
@@ -10,6 +10,7 @@ fi
 
 apt-get update
 apt-get upgrade -y
+# shellcheck disable=SC2086
 apt-get install -y --no-install-recommends ${PACKAGES}
 rm -rf /var/lib/apt/lists/*