Optimized Dockerfile to reduce layers and size

Dockerfile

@@ -1,14 +1,17 @@
 FROM ubuntu:18.04
-RUN apt-get update && apt-get upgrade -y && apt-get install wget gnupg expect -y && \
-    wget -O - https://packages.icinga.com/icinga.key | apt-key add -
-RUN printf "deb http://packages.icinga.com/ubuntu icinga-bionic main\ndeb-src http://packages.icinga.com/ubuntu icinga-bionic main" > /etc/apt/sources.list.d/icinga2.list && \
-    apt-get update && apt-get install icinga2 -y && \
+RUN apt-get update && apt-get install wget gnupg -y && \
+    printf "deb http://packages.icinga.com/ubuntu icinga-bionic main\ndeb-src http://packages.icinga.com/ubuntu icinga-bionic main" > /etc/apt/sources.list.d/icinga2.list && \
+    wget -O - https://packages.icinga.com/icinga.key | apt-key add - && \
+    apt-get update && apt-get --no-install-recommends install icinga2 monitoring-plugins tzdata -y && \
     mkdir /run/icinga2 && chown nagios:nagios /run/icinga2 && \
     mkdir -p /var/lib/icinga2/certs && \
-    chown -R nagios:nagios /var/lib/icinga2/certs
+    chown -R nagios:nagios /var/lib/icinga2/certs && \
+    apt-get remove -y wget gnupg && \
+    apt-get autoremove -y && \
+    apt-get clean 
 
 COPY create-satellite.sh /create-satellite.sh
 COPY run-icinga.sh /run-icinga.sh
 RUN chmod +x /create-satellite.sh ; chmod +x /run-icinga.sh
-
+EXPOSE 5665
 ENTRYPOINT ["/run-icinga.sh"]

README.md

@@ -3,8 +3,28 @@ An easy-to-use Dockerized Icinga2 satellite setup. It could be used as an
 Icinga2 agent aswell, but I don't think that would make much sense. The goal
 is instead to create an easy-to-deploy satellite Docker.
 
+## Tags
+
+### Main tags
+* **0.4, latest**
+* **0.3**
+* **0.2**
+* **0.1**
+
+### Alpine tags (currently has some problems)
+* **0.1.1-alpine**
+* **0.1-alpine**
+
+> **NOTE:** Currently there are some problems with the Alpine image. Use the main images
+> instead, tagged *0.n*.
+
+There are two available images for you to choose from. The default ones (0.*n*) are based on
+Ubuntu 18.04, with Icinga2 from Icingas official repository. The other images (0.*n*-alpine) is
+based on Alpine 3.11, with Icinga2 from Alpines repository. From 0.1.1-alpine and up, the Alpine
+image is built on the latest Alpine.
+
 ## Environment variables
-Everything is controlled using the follwing environment variables.
+Everything is controlled using the following environment variables.
 
 * **CN** is the Common Name of the satellite
 * **ZONE** is the zone in which this satellite should be in. If no zone is specified
@@ -17,15 +37,18 @@ Everything is controlled using the follwing environment variables.
 * **TICKET** is the ticket you get from the master (if you are using Director
   you find it under the Agent tab of the host).
 * **ACCEPT_CONFIG** takes a ***y*** or ***n*** value for yes or no. The default is
-  ***n***.
+  ***n***
 * **ACCEPT_COMMANDS** takes a ***y*** or ***n*** value for yes or no. The default is
-  ***n***.
+  ***n***
 * **DISABLE_CONFD** takes a ***y*** or ***n*** value for yes or no. The default is
   ***y***. This should be a sane default for most people.
+* **LOCAL_TIMEZONE** sets the local timezone of the satellite. For example
+  *Europe/Stockholm* or *America/New_York*
 
 ## Example usage
 ```
 #> docker run -d --name my-icinga-sat \
+  -p 5665:5665 \
   -e CN=icinga-sat02.local \
   -e PARENTHOST=icinga-master.local \
   -e PARENTCN=icinga-master.local \
@@ -41,6 +64,9 @@ version: "3.8"
 services:
   my-icinga-sat:
     image: jackbenny/icinga-satellite
+    ports:
+      - 5665:5665
+    restart:always
     environment:
       - CN=icinga-sat02.local
       - ZONE=icinga-sat02.local
@@ -51,5 +77,7 @@ services:
       - ACCEPT_CONFIG=y
       - ACCEPT_COMMANDS=y
       - DISABLE_CONFD=y
+      - LOCAL_TIMEZONE=Europe/Stockholm
 ```
 
+

create-satellite.sh

@@ -37,6 +37,11 @@ else
     DISABLE_CONF=" "
 fi
 
+# Set the local timezone
+if [ ! -z "$LOCAL_TIMEZONE" ]; then
+	ln -sf /usr/share/zoneinfo/"$LOCAL_TIMEZONE" /etc/localtime
+fi
+
 icinga2 pki new-cert --cn "$CN" \
 --key /var/lib/icinga2/certs/"${CN}".key \
 --cert /var/lib/icinga2/certs/"${CN}".crt