卷曲重试机制 [英] Curl retry mechanism

问题描述

我运行一个脚本来部署2个Web服务和一个前端应用程序。该脚本调用一种方法，以检查2个后端服务是否已启动并正在运行。如果是这样，则认为部署成功，否则恢复。

I have a script I run to deploy 2 web services and a front-end application. The script calls a method that checks to see if the 2 back-end services are up and running. If so, deem the deploy successful, otherwise revert.

这两项服务有时需要的时间比前端要长。目前，我打了个睡眠电话以延迟Web服务检查。

The 2 services sometimes take longer than the front-end to start up. Currently I put in a sleep call to delay the web service check. This allows them time to start up.

我想删除此睡眠并添加重试机制，以便在服务关闭时重复检查直到我再次尝试。

I want to remove this sleep and add in a retry mechanism so that if a service is down, just retry the check repeatedly until I get a response.

TP检查设备是否启动，我使用curl。我已经知道curl具有重试机制，但是我从未使用过。

Tp check if the device is up, I use curl. I've read that curl has a retry mechanism but I've never used it.

你们中的任何人以前解决过这个问题吗？我想了解解决问题时必须考虑的事项，例如我要重试，直到我从服务中获得HTTP 200吗？

Have any of you solved this problem before? I want to understand the things I must consider when solving it, e.g. do I retry until i get a HTTP 200 from my service?

有人建议我对此进行测试吗？我需要找到一个关闭的服务。

Anyone any suggestions how I'd test this? I'd need to find a service that was down.

编辑：我看到-​​retry只对瞬态错误做出反应'瞬态错误的意思是：超时，FTP 4xx响应代码或HTTP 5xx响应代码。我的服务可以返回404，因此curl的重试不是我的解决方案。

I see that -retry only reacts to transient errors 'Transient error means either: a timeout, an FTP 4xx response code or an HTTP 5xx response code'. My service can return a 404 therefore curl's retry is not my solution.

推荐答案

以下语句将重试5次或最多重试一次40秒，连接超时为5秒，并且没有指数补偿策略

The following statement will retry 5 times or a maximum of 40 seconds with a connection timeout of 5 seconds, and no exponential backoff policy

curl --connect-timeout 5 \
    --max-time 10 \
    --retry 5 \
    --retry-delay 0 \
    --retry-max-time 40 \
    'http://your_url'


--max-time 10     (how long each retry will wait)
--retry 5         (it will retry 5 times)
--retry-delay 0   (an exponential backoff algorithm)
--retry-max-time  (total time before it's considered failed)

请注意，还有一个-retry-connrefused （自curl 7.52.0起），即使连接为拒绝和-重试所有错误（自curl 7.71.0起），是重试的大锤。

Note that there is also a --retry-connrefused (since curl 7.52.0) that retries even when the connection is refused and --retry-all-errors (since curl 7.71.0) which "is the sledgehammer of retrying".

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