记录一次prometheus因时区不同导致的无法获取数据问题

一、故障出现原因

prometheus机器压力过大，内存耗尽，负载飙高，导致无法登录；

于是从公有云web界面进行重启，重启后内存还是不足，负载很快升高；

对机器进行配置变更，由4C+8G升级为4C+16G；

二、故障表现

Grafana无法获取指标、但是可以通过curl命令获取远程目标主机暴露的指标；

日志有以下报错

level=warn ts=2024-05-23T11:04:46.410Z caller=scrape.go:1094 component="scrape manager" scrape_pool=jws2-development-hangzhou target=http://172.16.185.173:9100/metrics msg="Appending scrape report failed" err="out of bounds"
level=warn ts=2024-05-23T11:04:46.423Z caller=scrape.go:1378 component="scrape manager" scrape_pool=jws2-development-hangzhou target=http://172.16.185.182:9100/metrics msg="Error on ingesting samples that are too old or are too far into the future" num_dropped=507
level=warn ts=2024-05-23T11:04:46.423Z caller=scrape.go:1094 component="scrape manager" scrape_pool=jws2-development-hangzhou target=http://172.16.185.182:9100/metrics msg="Appending scrape report failed" err="out of bounds"
level=warn ts=2024-05-23T11:04:46.505Z caller=scrape.go:1378 component="scrape manager" scrape_pool=jws2-development-hangzhou target=http://172.16.185.172:9100/metrics msg="Error on ingesting samples that are too old or are too far into the future" num_dropped=435
level=warn ts=2024-05-23T11:04:46.505Z caller=scrape.go:1094 component="scrape manager" scrape_pool=jws2-development-hangzhou target=http://172.16.185.172:9100/metrics msg="Appending scrape report failed" err="out of bounds"
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三、解决办法

1、调整时区与目标主机相同

获取当前时间与时区

timedatactl
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调整时区为上海

 timedatectl set-timezone Asia/Shanghai
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调整硬件时间为UTC

2、删除wal文件

wal文件作用：仅用于记录事件和在启动时恢复内存状态，

[root@iZbp15tsl5bp6tjrwi2ksjZ data]# mv wal /tmp/
[root@iZbp15tsl5bp6tjrwi2ksjZ data]# mkdir wal
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删除文件后，再次进行重启，日志恢复正常，Grafana显示正常

四、原因

当变更机器规格是，系统时间改变为UTC时间，目标主机为上海时区，Prometheus 从新的时间记录数据，现在的日期与 Prometheus 记录的日期冲突（太旧了），所以它报告“Error on ingesting samples that are too old or are too far into the future”

参考：https://github.com/prometheus/prometheus/issues/6554