diff --git a/bitnami/alertmanager/0/debian-10/Dockerfile b/bitnami/alertmanager/0/debian-10/Dockerfile
index 15f57ceeb4d5..5f46c83b030b 100644
--- a/bitnami/alertmanager/0/debian-10/Dockerfile
+++ b/bitnami/alertmanager/0/debian-10/Dockerfile
@@ -1,8 +1,9 @@
 FROM docker.io/bitnami/minideb:buster
 LABEL maintainer "Bitnami <containers@bitnami.com>"
 
+COPY prebuildfs /
 # Install required system packages and dependencies
-RUN install_packages ca-certificates curl procps sudo unzip wget
+RUN install_packages ca-certificates curl gzip procps tar wget
 RUN wget -nc -P /tmp/bitnami/pkg/cache/ https://downloads.bitnami.com/files/stacksmith/alertmanager-0.20.0-0-linux-amd64-debian-10.tar.gz && \
     echo "7a6aa1997a31c2f19899548667334012e2a0db5918ab74c55c98f00322d14711  /tmp/bitnami/pkg/cache/alertmanager-0.20.0-0-linux-amd64-debian-10.tar.gz" | sha256sum -c - && \
     tar -zxf /tmp/bitnami/pkg/cache/alertmanager-0.20.0-0-linux-amd64-debian-10.tar.gz -P --transform 's|^[^/]*/files|/opt/bitnami|' --wildcards '*/files' && \
@@ -14,7 +15,11 @@ RUN ln -sf /opt/bitnami/alertmanager/data /alertmanager
 
 RUN mkdir -p /opt/bitnami/alertmanager/data/ && chmod g+rwX /opt/bitnami/alertmanager/data/
 ENV BITNAMI_APP_NAME="alertmanager" \
-    BITNAMI_IMAGE_VERSION="0.20.0-debian-10-r84" \
+    BITNAMI_IMAGE_VERSION="0.20.0-debian-10-r85" \
+    HOME="/" \
+    OS_ARCH="amd64" \
+    OS_FLAVOUR="debian-10" \
+    OS_NAME="linux" \
     PATH="/opt/bitnami/alertmanager/bin:$PATH"
 
 EXPOSE 9093
diff --git a/bitnami/alertmanager/0/debian-10/prebuildfs/usr/sbin/install_packages b/bitnami/alertmanager/0/debian-10/prebuildfs/usr/sbin/install_packages
new file mode 100755
index 000000000000..c9577647443b
--- /dev/null
+++ b/bitnami/alertmanager/0/debian-10/prebuildfs/usr/sbin/install_packages
@@ -0,0 +1,24 @@
+#!/bin/sh
+set -e
+set -u
+export DEBIAN_FRONTEND=noninteractive
+n=0
+max=2
+until [ $n -gt $max ]; do
+    set +e
+    (
+      apt-get update -qq &&
+      apt-get install -y --no-install-recommends "$@"
+    )
+    CODE=$?
+    set -e
+    if [ $CODE -eq 0 ]; then
+        break
+    fi
+    if [ $n -eq $max ]; then
+        exit $CODE
+    fi
+    echo "apt failed, retrying"
+    n=$(($n + 1))
+done
+rm -r /var/lib/apt/lists /var/cache/apt/archives
diff --git a/bitnami/alertmanager/README.md b/bitnami/alertmanager/README.md
index a551f25c17b6..729d02cee788 100644
--- a/bitnami/alertmanager/README.md
+++ b/bitnami/alertmanager/README.md
@@ -32,7 +32,7 @@ Non-root container images add an extra layer of security and are generally recom
 Learn more about the Bitnami tagging policy and the difference between rolling tags and immutable tags [in our documentation page](https://docs.bitnami.com/tutorials/understand-rolling-tags-containers/).
 
 
-* [`0-debian-10`, `0.20.0-debian-10-r84`, `0`, `0.20.0`, `latest` (0/debian-10/Dockerfile)](https://github.com/bitnami/bitnami-docker-alertmanager/blob/0.20.0-debian-10-r84/0/debian-10/Dockerfile)
+* [`0-debian-10`, `0.20.0-debian-10-r85`, `0`, `0.20.0`, `latest` (0/debian-10/Dockerfile)](https://github.com/bitnami/bitnami-docker-alertmanager/blob/0.20.0-debian-10-r85/0/debian-10/Dockerfile)
 
 Subscribe to project updates by watching the [bitnami/alertmanager GitHub repo](https://github.com/bitnami/bitnami-docker-alertmanager).