Add cAdvisor image for Prometheus monitoring.

cAdvisor is a performance monitoring tool for containers which can be used
in conjunction with Prometheus.

Change-Id: Ib329fa30e8ab1c969b3b21bcbccf26bd562b9b83

docker/prometheus/prometheus-cadvisor/Dockerfile.j2

@@ -0,0 +1,16 @@
+FROM {{ namespace }}/{{ image_prefix }}prometheus-base:{{ tag }}
+LABEL maintainer="{{ maintainer }}" name="{{ image_name }}" build-date="{{ build_date }}"
+
+{% block prometheus_cadvisor_header %}{% endblock %}
+
+{% block prometheus_cadvisor_repository_version %}
+ENV prometheus_cadvisor_version=0.27.4
+{% endblock %}
+
+{% block prometheus_cadvisor_install %}
+RUN curl -ssL -o /opt/cadvisor https://github.com/google/cadvisor/releases/download/v${prometheus_cadvisor_version}/cadvisor \
+    && chmod 755 /opt/cadvisor
+{% endblock %}
+
+{% block prometheus_cadvisor_footer %}{% endblock %}
+{% block footer %}{% endblock %}

releasenotes/notes/prometheus-cadvisor-05906b0894651a29.yaml

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+---
+features:
+  - Added a container image for cAdvisor, to be used with Prometheus
+    monitoring to gather resource utilization statistics of containers.