cdn_check_exporter
CDN check is an Prometheus exporter that helps monitoring assets served by a content delivery network.
When serving content using a CDN, many hosts will serve the content, so there is no (normally) a fixed set of IPs to query to. This service queries DNS to discover IPs and then queries the hosts for the content.
Basically it makes curl http://123.123.123.13/resource -H "Host: www.example.com" but in an automated way that allows to find if the content is the expected (by looking at the bytes returned), the error code returned and its availabilty.
go run main.go -h
Usage of /tmp/go-build3023912900/b001/exe/main:
-debug=false: see that the service is doing
-domain="": domain to query to
-every=10: number of seconds to wait between requests
-metrics.ip="0.0.0.0:9000": IP and Port for the metrics exporter
-metrics.path="/metrics": path under metrics are exposed
-resource="": resource(s) to query to, separated by commas
Every flag can be passed as environment variable, sample:
DOMAIN="www.google.com" RESOURCE="/images/branding/googlelogo/2x/googlelogo_color_272x92dp.png" ./cdn_check_exporter
Output:
curl http://127.0.0.1:9000/metrics
# HELP dd_request request error code
# TYPE dd_request gauge
dd_request{ip="142.250.184.4",resource="/images/branding/googlelogo/2x/googlelogo_color_272x92dp.png"} 200
dd_request{ip="142.250.201.68",resource="/images/branding/googlelogo/2x/googlelogo_color_272x92dp.png"} 200
# HELP dd_request_bytes request length
# TYPE dd_request_bytes gauge
dd_request_bytes{ip="142.250.184.4",resource="/images/branding/googlelogo/2x/googlelogo_color_272x92dp.png"} 13504
dd_request_bytes{ip="142.250.201.68",resource="/images/branding/googlelogo/2x/googlelogo_color_272x92dp.png"} 13504
# HELP dd_request_last_update request last update for this IP
# TYPE dd_request_last_update gauge
dd_request_last_update{ip="142.250.184.4",resource="/images/branding/googlelogo/2x/googlelogo_color_272x92dp.png"} 1.665413412e+09
dd_request_last_update{ip="142.250.201.68",resource="/images/branding/googlelogo/2x/googlelogo_color_272x92dp.png"} 1.665413412e+09
# HELP dd_request_success request was success
# TYPE dd_request_success gauge
dd_request_success{ip="142.250.184.4",resource="/images/branding/googlelogo/2x/googlelogo_color_272x92dp.png"} 1
dd_request_success{ip="142.250.201.68",resource="/images/branding/googlelogo/2x/googlelogo_color_272x92dp.png"} 1
# HELP dd_request_time request time in ms
# TYPE dd_request_time gauge
dd_request_time{ip="142.250.184.4",resource="/images/branding/googlelogo/2x/googlelogo_color_272x92dp.png"} 25
dd_request_time{ip="142.250.201.68",resource="/images/branding/googlelogo/2x/googlelogo_color_272x92dp.png"} 27
...
Do not probe for systemd unless requested
Service makes a health check on intervals and notify systemd, but there are several times where this is not needed, like on a container (where health checks must be configured on the platform)
TODO: Make optional via argument systemd notifications.