Add a health check to the container

Author: gregcorbett

Dockerfile

@@ -12,7 +12,7 @@ RUN yum -y install python3
 # Install the python requirements of container accounting
 RUN pip3 install -r ./requirements.txt
 
-# Set PYTHONPATH so Python can import the necessary files at run time. 
+# Set PYTHONPATH so Python can import the necessary files at run time.
 ENV PYTHONPATH=/usr/share/container_accounting
 
 # To avoid running the container as root, create an apel user.
@@ -22,4 +22,10 @@ RUN chown -R apel:apel /usr/share/container_accounting
 # Set the default user of the container to apel.
 USER apel:apel
 
-ENTRYPOINT ./entrypoint.sh 
+# Set a healthcheck for this container, and give the container 30 seconds
+# after start up where the health of the container will not be checked.
+# This makes it likely the underlying python call will have returned at least
+# once before the health check is called.
+HEALTHCHECK --start-period=30s CMD ./healthcheck.sh
+
+ENTRYPOINT ./entrypoint.sh

healthcheck.sh

@@ -0,0 +1,7 @@
+#!/bin/sh
+
+# A simple scrip to pass the stored return code of the python process back to
+# the caller for the purposes of a container health check.
+
+exit `cat status.txt`
+