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