如何使用AWS CLI获取最近启动的EC2实例? [英] How to get the most recently launched EC2 instance with AWS CLI?
问题描述
我当前正在使用以下CLI命令来获取给定实例 Name 标签'myInstanceName'的实例 PublicIPAddress 和 LaunchTime :
I'm currently using the following CLI command to get the instance PublicIPAddress and LaunchTime for a given instance Name tag, 'myInstanceName':
aws ec2 describe-instances --filters 'Name=tag:Name,Values=myInstanceName' \
--region us-east-1 \
--query 'Reservations[*].Instances[*].{PublicIpAddress: PublicIpAddress, LaunchTime: LaunchTime}'
结果如下:
[
{
"LaunchTime": "2019-01-25T11:49:06.000Z",
"PublicIpAddress": "11.111.111.11"
}
]
这很好,但是如果有两个同名实例,我将在结果JSON中得到两个结果。我需要找到一种获取给定名称的最新实例的方法。
This is fine, but if there are two instances with the same name I will get two results in my result JSON. I need to find a way to get the most recent instance for a given name.
解决方案更新
此问题非常特定于EC2实例。可以使用两种不同的方法来解决该问题,请在下面回答:
使用jq解析结果
使用JMESPath
This question is quite specific to EC2 instances. The issue can be resolved using two different methods, answered below:
Parsing Result with jq
Using JMESPath
请参见<一个href = https://stackoverflow.com/questions/42414156/sort-by-date-with-jmespath>相关问题,以便使用JMESPath按日期进行更常规的排序,并进行进一步的阅读。
Please see this related question for more general sorting by date with JMESPath, and for further reading.
推荐答案
尝试使用 jq 实用程序。这是一个命令行JSON解析器。如果您不熟悉它,建议您使用 jq游乐场进行试验。
Try using the jq utility. It's a command-line JSON parser. If you're not familiar with it then I'd recommend the jq playground for experimentation.
首先展平awcli结果,如下:
First flatten the awcli results, as follows:
aws ec2 describe-instances \
--query 'Reservations[].Instances[].{ip: PublicIpAddress, tm: LaunchTime}' \
--filters 'Name=tag:Name,Values= myInstanceName'
请注意,我已经将 LaunchTime
别名为 tm
为简洁起见。这样将导致(未排序的)输出,如下所示:
Note that I've aliased LaunchTime
to tm
for brevity. That will result in (unsorted) output like this:
[
{
"ip": "54.4.5.6",
"tm": "2019-01-04T19:54:11.000Z"
},
{
"ip": "52.1.2.3",
"tm": "2019-03-04T20:04:00.000Z"
}
]
接下来,将此结果通过管道传递到 jq
并按 tm
降序进行排序 LaunchTime
),如下所示:
Next, pipe this result into jq
and sort by descending tm
(the alias for LaunchTime
), as follows:
jq 'sort_by(.tm) | reverse'
这将导致如下输出:
[
{
"ip": "52.1.2.3",
"tm": "2019-03-04T20:04:00.000Z"
},
{
"ip": "54.4.5.6",
"tm": "2019-01-04T19:54:11.000Z"
}
]
最后,使用 jq
过滤掉除第一个结果以外的所有结果,如下所示:
Finally, use jq
to filter out all but the first result, as follows:
jq 'sort_by(.tm) | reverse | .[0]'
这将产生一个结果,即最近启动的实例:
This will yield one result, the most recently launched instance:
{
"ip": "52.1.2.3",
"tm": "2019-03-04T20:04:00.000Z"
}
将它们放在一起,最终命令是:
Putting it all together, the final command is:
aws ec2 describe-instances \
--query 'Reservations[].Instances[].{ip: PublicIpAddress, tm: LaunchTime}' \
--filters 'Name=tag:Name,Values= myInstanceName' | \
jq 'sort_by(.tm) | reverse | .[0]'
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