A Juju charm for deploying and managing a content cache.
A service for caching content, built on top of HAProxy and Nginx configurable to cache any http or https web site. Tuning options include cache storage size, maximum request size to cache and cache validity duration.
This service was developed to provide front-end caching for web sites run by Canonical's IS team, and to reduce the need for third-party CDNs by providing high-bandwidth access to web sites via this caching front-end. Currently used for a number of services including the Snap Store, the majority of Canonical's web properties including ubuntu.com and canonical.com, and Ubuntu Extended Security Maintenance.
See also the Kubernetes version of this charm.
To deploy the charm:
juju deploy content-cache
For details on configuring sites, see the sites configuration documentation.
To get metrics:
juju deploy telegraf
juju add-relation telegraf:haproxy content-cache:haproxy-statistics
You can then query the telegraf endpoint to get HAProxy metrics from the content-cache charm.
To get cache hits metrics:
juju config content-cache enable_prometheus_metrics=true
This will expose the following metrics for each site configured:
# HELP nginx_cache_request_hit_total Number of cache hits per site
# TYPE nginx_cache_request_hit_total counter
nginx_cache_request_hit_total{host="myhost"} 10
# HELP nginx_cache_request_total Number of cache requests per site
# TYPE nginx_cache_request_total counter
nginx_cache_request_total{host="myhost"} 20
# HELP nginx_http_request_total Number of HTTP requests per site
# TYPE nginx_http_request_total counter
nginx_http_request_total{host="myhost",status="200"} 110129
# HELP nginx_metric_errors_total Number of nginx-lua-prometheus errors
# TYPE nginx_metric_errors_total counter
nginx_metric_errors_total 0
For further details, see here.