Powershell get region from AWS metadata

Question

I have an EC2 instance and I am running a Powershell script there where I would like to get the region that the EC2 is running in.

Currently I have workaround like this which grabs the availability zone first. The availability zone is in the format like 'us-east-1a'.

$region = invoke-restmethod -uri http://169.254.169.254/latest/meta-data/placement/availability-zone 
if ($region -like "*east*") {$region = "us-east-1"} ELSE {$region = "us-west-2"}

I would like to just grab the region, rather than get the availability zone and then do some modifications. I know there is a possibility to use:

http://169.254.169.254/latest/dynamic/instance-identity/document

This returns a JSON object which has the region, but I would also need to parse the JSON to achieve this.

How do I get just the region?

Davide DG · Answer 1 · 2018-06-14T20:00:33.767

8

You can use ConvertFrom-Json :

PS C:\> $region = (Invoke-WebRequest -UseBasicParsing -Uri http://169.254.169.254/latest/dynamic/instance-identity/document | ConvertFrom-Json | Select region).region

edit: added -UseBasicParsing

edited Jun 14 '18 at 20:00

answered Jun 05 '18 at 16:34

Davide DG

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1
4

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Simplified to `(Invoke-RestMethod http://169.254.169.254/latest/dynamic/instance-identity/document).region` – Stoinov Mar 13 '20 at 14:30

score 6 · Accepted Answer · answered Aug 22 '17 at 18:06

6

Will this work?

PS C:\> $region = invoke-restmethod -uri http://169.254.169.254/latest/meta-data/placement/availability-zone

PS C:\> $region.Substring(0,$region.Length-1)

answered Aug 22 '17 at 18:06

helloV

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Yea, that solution will work since it seems that all the availability zones have a single letter tacked onto the end. Discovered there's no native way to grab the region with a single command. Thank you. – William Ross Aug 22 '17 at 18:13

score 4 · Answer 3 · answered May 17 '19 at 03:11

Parsing the availability-zone is not the safest way. Region name is available as an attribute of the Instance Identity Document, which is generated when the instance is launched. There are two options to read this information with Powershell:

You could use Invoke-WebRequest:

IWR (also aliased as curl and wget) works fine, but it can only deal with HTML. So you need an extra step to parse JSON. It uses the IE COM interface to parse the DOM by default, but you can avoid that with the -UseBasicParsing option.

PS C:\> curl http://169.254.169.254/latest/dynamic/instance-identity/document | ConvertFrom-Json | Select region

region
------
us-east-1

PS C:\> (curl http://169.254.169.254/latest/dynamic/instance-identity/document | ConvertFrom-Json).region
us-east-1

But Invoke-RestMethod is the best option:

Since this is a REST interface, IRM is the best choice because it natively supports JSON and XML.

PS C:\> irm http://169.254.169.254/latest/dynamic/instance-identity/document | Select region

region
------
us-east-1

PS C:\> (irm http://169.254.169.254/latest/dynamic/instance-identity/document).region
us-east-1

PS C:\> irm http://169.254.169.254/latest/dynamic/instance-identity/document | % region
us-east-1

score 1 · Answer 4 · answered Aug 22 '17 at 17:45

Try using :

EC2_AVAIL_ZONE=`curl -s http://169.254.169.254/latest/meta-data/placement/availability-zone`
EC2_REGION="`echo \"$EC2_AVAIL_ZONE\" | sed -e 's:\([0-9][0-9]*\)[a-z]*\$:\\1:'`"

OR

EC2_INSTANCE_ID="`wget -q -O - http://169.254.169.254/latest/meta-data/instance-id || die \"wget instance-id has failed: $?\"`"test -n "$EC2_INSTANCE_ID" || die 'cannot obtain instance-id'

EC2_AVAIL_ZONE="`wget -q -O - http://169.254.169.254/latest/meta-data/placement/availability-zone || die \"wget availability-zone has failed: $?\"`"test -n "$EC2_AVAIL_ZONE" || die 'cannot obtain availability-zone'

EC2_REGION="`echo \"$EC2_AVAIL_ZONE\" | sed -e 's:\([0-9][0-9]*\)[a-z]*\$:\\1:'`"

JQ:

curl -s http://169.254.169.254/latest/dynamic/instance-identity/document | jq .region -r

Reference : Instance Metadata

Note: This has to be run from inside the EC2 instance because that IP is an APIPA. There is no way to get this information directly from inside the instance without connecting to a metadata source

Hope it helps

Looks like those are Linux commands... was wondering how I can do the same in Powershell? — William Ross, Aug 22 '17 at 17:52
@helloV: My bad. Invoke-webrequest will do that instead of curl :) — Ranadip Dutta, Aug 23 '17 at 02:47

score 0 · Answer 5 · answered Mar 03 '22 at 14:57

0

$region = Get-EC2InstanceMetadata -Category region

write-output "Get region:"

write-output $region.SystemName

answered Mar 03 '22 at 14:57

Dirty Harry

1

While this code snippet may solve the problem, it doesn't explain why or how it answers the question. Please [include an explanation for your code](//meta.stackexchange.com/q/114762/269535), as that really helps to improve the quality of your post. Remember that you are answering the question for readers in the future, and those people might not know the reasons for your code suggestion. – Luca Kiebel Mar 03 '22 at 14:59
As it’s currently written, your answer is unclear. Please [edit] to add additional details that will help others understand how this addresses the question asked. You can find more information on how to write good answers [in the help center](/help/how-to-answer). – Community Mar 04 '22 at 02:32

Powershell get region from AWS metadata

5 Answers5

You could use Invoke-WebRequest:

But Invoke-RestMethod is the best option: