1.4 KiB
Pinging Reliability Tips
Sending monitoring signals over public internet is inherently unreliable. HTTP requests can sometimes take excessively long or fail completely for a variety of reasons. Here are some general tips to make your monitoring code more robust.
Specify HTTP Request Timeout
Put a time limit on how long each ping is allowed to take. This is especially important when sending a "start" signal at the start of a job: you don't want a stuck ping prevent the actual job from running. Another case is a continuously running worker process which pings SITE_NAME after each completed item. A stuck request would block the whole process, so it is important to guard against.
Specifying the timeout depends on the tool you use. curl, for example, has the
--max-time (shorthand: -m) parameter:
# Send a HTTP, 10 second timeout:
curl -m 10 PING_URL
Use Retries
To minimize the amount of false alerts you get from SITE_NAME, instruct your HTTP client to retry failed requests several times.
Specifying the retry policy depends on the tool you use. curl, for example, has the
--retry parameter:
# Retry up to 5 times, uses an increasing delay between each retry (1s, 2s, 4s, 8s, ...)
curl --retry 5 PING_URL
Handle Exceptions
Make sure you know how your HTTP client handles failed requests. For example, if you use a HTTP library which raises exceptions, decide if you want to catch the exceptions, or let them bubble up.