PowerShell AWS CLI and json

When you work with Amazon cloud, you often have to perform many routine tasks through the Web console. But I want to automate.
AWS CLI, command line interface, well-suited for this. Of course, you can write the application in Scala, but in everyday tasks better oboitis without "heavy artillery".
Team AWS can return data in different formats, including json. You can use bash and jq, but the latter is not in the cygwin repository, and install laziness. Meanwhile, in PowerShell has great support for json! The truth was that to use this is not very simple.
the

C:\Users\mpotanin> $instance = aws ec2 describe-instances --instance-ids i-ecf1fe5c
C:\Users\...> ConvertFrom-Json $instance
ConvertFrom-Json : Cannot  convert  'System.Object[]' to the type 'System.String' required by parameter 'InputObject'. The specified method is not supported.
At line:1 char:19
+ ConvertFrom-Json $instance
+ ~~~~~~~~~
+ CategoryInfo : InvalidArgument: (:) [ConvertFrom-Json], ParameterBindingException
+ FullyQualifiedErrorId : CannotConvertArgument,Microsoft.PowerShell.Commands.ConvertFromJsonCommand

The fact that json is provided in the form of several lines, and is treated as an array. Feed it in PowerShell in different ways:
the

$instance | ConvertFrom-Json
ConvertFrom-Json ($instance -join "")
ConvertFrom-Json "$instance"

To get the right information now not difficult:
the

(aws ec2 describe-instances --instance-ids i-ecf1fe5c | ConvertFrom-Json).Reservations[0].Instances[0].PublicIpAddress

In simple cases, the extraction of the information may be turned over to aws:
the

aws ec2 describe-instances --instance-ids i-ecf1fe5c --query 'Reservations[0].Instances[0].PublicIpAddress' | ConvertFrom-Json

or even
the

aws ec2 describe-instances --instance-ids i-ecf1fe5c --query 'Reservations[0].Instances[0].PublicIpAddress' --output=text

Thus, observing the strange behavior of the autoscaling group via console, I can copy with the mouse the name of the instance and log in via ssh:
the

function get-address([String]$instanceId) {
aws ec2 describe-instances --instance-ids $instanceId --query 'Reservations[0].Instances[0].PublicIpAddress' | convertfrom-json
}

ssh-i devkey.pem -l ubuntu (get-address i-ecf1fe5c)

In more complex cases it is necessary to have to write non-trivial code. For example, to obtain the output parameters of the cloud formation stack as follows:
the

function reduce ($f,$a) {
if ($a.Length-eq 1) {
$a
} else {
$p = $a[0]
foreach ($x in 1..($a.Length-1)) {
$p = $f.Invoke($p,$a[$x])[0]
}
$p
}
}

function get-json($data) {
ConvertFrom-json "$data"
}

function get-cf-outputs($cfName) {
$o = (get-json(aws cloudformation describe-stacks --stack-name $cfName)).Stacks[0].Outputs
$r = foreach($i in $o) { @{$i.OutputKey = $i.OutputValue} }
reduce {param($a,$i); $a+$i } $r
}

Now I can get the connection parameters with the database team
the

(get-cf outputs microservice-rds-dev).DatabaseEndpoint

Transfer json in the command aws cli also brings surprises. For example, trying to add a record in dynamodb table just fails:
the

C:\Users\...> aws dynamodb put-item --table-name tableName --item '{"groupId":{"S":"5"}, "ancestors":{"L":[{"S":"5"},{"S":"0"}]}}'

Error parsing parameter '--item': Invalid JSON: Expecting property name enclosed in double quotes: line 1 column 2 (char 1)

That is, somewhere deep aws cli interpretiruya this string before passing it json library. (If this were bash, I would understand, but why would need to program in Python is beyond my comprehension.)
To get around this odd behavior is enough to escape the special characters:
the

function put-item([string]$table, $data) {
aws dynamodb put-item --table-name $table --item (convertto-json -Depth 128 $data).Replace('\','\\').Replace('"','\"')
}

Basically, PowerShell is and native AWS-client, but I thought it was more complicated and worse documented.

Article based on information from habrahabr.ru