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- # 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:
-
- ```bash
- # 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:
-
- ```bash
- # 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.
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