diff --git a/.github/workflows/linters.yml b/.github/workflows/linters.yml
index caafaaf7..378f34c6 100644
--- a/.github/workflows/linters.yml
+++ b/.github/workflows/linters.yml
@@ -34,7 +34,7 @@ jobs:
       - uses: hadolint/hadolint-action@v2.1.0
         with:
           recursive: true
-          ignore: DL3041
+          ignore: DL3041,DL3008
           dockerfile: Dockerfile.${{ matrix.package }}
 
   shellcheck:
diff --git a/Dockerfile.agent b/Dockerfile.agent
index 4b833d7d..a04eb915 100644
--- a/Dockerfile.agent
+++ b/Dockerfile.agent
@@ -1,14 +1,14 @@
 FROM docker.io/library/python:3.10.7-slim
 
-RUN apt update && apt install -y libyang-tools libxml2-utils make curl && rm -rf /var/lib/apt/lists/*
+RUN apt update && apt install -y --no-install-recommends libyang-tools libxml2-utils make curl && rm -rf /var/lib/apt/lists/*
 
 # certificates
+SHELL ["/bin/ash", "-eo", "pipefail", "-c"]
 RUN curl -kL https://watsen.net/support/sztpd-simulator-0.0.11.tgz | tar -zxvf - -C /tmp/
 WORKDIR /tmp/sztpd-simulator/pki
-RUN sed -i 's/localhost/bootstrap/g' sztpd1/sbi/end-entity/openssl.cnf
-RUN make pki
+RUN sed -i "s/localhost/bootstrap/g" sztpd1/sbi/end-entity/openssl.cnf && \
+    make pki
+    echo # create trust chain && \
+    cat sztpd1/sbi/root-ca/my_cert.pem sztpd1/sbi/intermediate1/my_cert.pem > /opi.pem
 
-# create trust chain
-RUN cat sztpd1/sbi/root-ca/my_cert.pem sztpd1/sbi/intermediate1/my_cert.pem > /opi.pem
-
-CMD ['/bin/sh', '-c', 'sleep infinity']
+CMD ["/bin/sh", "-c", "sleep infinity"]
diff --git a/Dockerfile.bootstrap b/Dockerfile.bootstrap
index 340007a3..ee88c2b4 100644
--- a/Dockerfile.bootstrap
+++ b/Dockerfile.bootstrap
@@ -1,29 +1,29 @@
 FROM docker.io/library/python:3.10.7-slim
 
-RUN apt-get update && apt-get install -y gettext libsqlite3-dev make curl && rm -rf /var/lib/apt/lists/*
+RUN apt-get update && apt-get install -y --no-install-recommends gettext libsqlite3-dev make curl && rm -rf /var/lib/apt/lists/*
 RUN pip install --no-cache-dir sztpd==0.0.11
 
 # certificates
+SHELL ["/bin/ash", "-eo", "pipefail", "-c"]
 RUN curl -kL https://watsen.net/support/sztpd-simulator-0.0.11.tgz | tar -zxvf - -C /tmp/
 WORKDIR /tmp/sztpd-simulator/pki
-RUN sed -i 's/localhost/bootstrap/g' sztpd1/sbi/end-entity/openssl.cnf
-RUN make pki
-
-# SBI Port certificates
-RUN cat sztpd1/sbi/end-entity/my_cert.pem sztpd1/sbi/intermediate2/my_cert.pem > /tmp/cert_chain.pem
-RUN openssl crl2pkcs7 -nocrl -certfile /tmp/cert_chain.pem -outform DER -out /tmp/cert_chain.cms
-
-# client cert (DevID) trust anchor
-RUN cat client/root-ca/my_cert.pem client/intermediate1/my_cert.pem client/intermediate2/my_cert.pem > /tmp/ta_cert_chain.pem
-RUN openssl crl2pkcs7 -nocrl -certfile /tmp/ta_cert_chain.pem -outform DER -out /tmp/ta_cert_chain.cms
-
-# TODO: remove this line and run test from agent container instead
-RUN cat sztpd1/sbi/root-ca/my_cert.pem sztpd1/sbi/intermediate1/my_cert.pem > /opi.pem
+RUN sed -i 's/localhost/bootstrap/g' sztpd1/sbi/end-entity/openssl.cnf && \
+    make pki && \
+    echo # SBI Port certificates && \
+    cat sztpd1/sbi/end-entity/my_cert.pem sztpd1/sbi/intermediate2/my_cert.pem > /tmp/cert_chain.pem && \
+    openssl crl2pkcs7 -nocrl -certfile /tmp/cert_chain.pem -outform DER -out /tmp/cert_chain.cms && \
+    echo # client cert (DevID) trust anchor && \
+    cat client/root-ca/my_cert.pem client/intermediate1/my_cert.pem client/intermediate2/my_cert.pem > /tmp/ta_cert_chain.pem && \
+    openssl crl2pkcs7 -nocrl -certfile /tmp/ta_cert_chain.pem -outform DER -out /tmp/ta_cert_chain.cms && \
+    echo # TODO: remove this line and run test from agent container instead && \
+    cat sztpd1/sbi/root-ca/my_cert.pem sztpd1/sbi/intermediate1/my_cert.pem > /opi.pem
 
 # configurations, images, templates
 COPY config/ /tmp/
 
 # generate static template
+
+# hadolint ignore=SC2016
 RUN \
     BOOT_IMG_HASH_VAL=`openssl dgst -sha256 -c /tmp/my-boot-image.img | awk '{print $2}'` \
     PRE_SCRIPT_B64=`openssl enc -base64 -A -in /tmp/my-pre-configuration-script.sh` \
diff --git a/Dockerfile.client b/Dockerfile.client
index 6df44144..17df5973 100644
--- a/Dockerfile.client
+++ b/Dockerfile.client
@@ -1,4 +1,4 @@
 FROM docker.io/library/fedora:36
-RUN dnf install -y dhclient
+RUN dnf install -y dhclient && dnf clean all
 COPY ./dhclient.conf /etc/dhcp/
 CMD ["dhclient", "-d", "-v"]
diff --git a/Dockerfile.dhcp b/Dockerfile.dhcp
index 1010b584..606b3d90 100644
--- a/Dockerfile.dhcp
+++ b/Dockerfile.dhcp
@@ -1,4 +1,4 @@
 FROM docker.io/library/fedora:36
-RUN dnf install -y dhcp-server gettext
+RUN dnf install -y dhcp-server gettext && dnf clean all
 COPY ./dhcpd.conf.template /etc/dhcp/
 CMD ["dhcpd", "-d"]