Check if string is in list of strings

Question

Context: We are making an API to get a list of all VMs and the filter it, using if loops, to return only VMs with name starting only with the values in $MachineList.

The list of servers is split in 2:

• set 1: srv-a-1, srv-a-2, srv-b-1, srv-b-2, srv-c-1, srv-c-2, etc.
• set 2: tst-a-1, tst-a-2, tst-b-1, tst-b-2, tst-c-1, tst-c-2, etc.

This is the script:

$EnvironmentList = "Environments-4" -or "Environments-5" -or "Environments-41" -or "Environments-61"
$MachineList = "srv-a*" -or "srv-b*" -or "srv-c*" -or "srv-d*" -or "srv-e*" -or "srv-f*" -or "srv-g*" -or "srv-h*" -or" srv-i*" -or "srv-j*" -or "srv-k*" -or "srv-l*"

function CheckService {
    $MachinesRequest = (Invoke-WebRequest -Method Get -Headers @{"X-system-ApiKey"="Hashed-API-Key-Value"} -URI https://url-to-site.local/api/machines/all).Content | ConvertFrom-Json
    foreach ($Machine in $MachinesRequest) {
        if ($EnvironmentList -contains $Machine.EnvironmentIds) {
            if ($MachineList -contains $Machine.Name) {
                $Machine.Name
            }
        }
    }
}

CheckService

We're trying to return just the items which match the values in the machine list however this is returning the full list of machines (both srv* and tst*).

Solution

First and foremost, $MachineList = "srv-a*" -or "srv-b*" -or ... won't do what you apparently think it does. It's a boolean expression that evaluates to $true, because PowerShell interprets non-empty strings as $true in a boolean context. If you need to define a list of values, define a list of values:

$MachineList = "srv-a*", "srv-b*", ...

Also, the -contains operator does exact matches (meaning it checks if any of the values in the array is equal to the reference value). For wildcard matches you need a nested Where-Object filter

$MachineList = "srv-a*", "srv-b*", "srv-c*", ...
...
if ($MachineList | Where-Object {$Machine.Name -like $_}) {
    ...
}

A better approach in this scenario would be a regular expression match, though, e.g.:

$pattern = '^srv-[a-l]'
...
if ($Machine.Name -match $pattern) {
    ...
}