AWS Lambda blueprint to lookup AMI IDs by AMI Name
This blueprint mirrors the blueprint of the same name provide by AWS, with the following enhancements:
- Removes the restriction on looking up only AMI IDs owned by Amazon
- Uses a new parameter,
AmiNameSearchString
, as the match pattern against AMI Names. Previously, the pattern was hard-coded in the blueprint - Improves error logging when the pattern does not match any images
Before creating the Lambda function, first create an IAM role with the
following policy to use with this blueprint. For convenience, name the role
something like cfn-look-up-ami-ids
.
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": [
"logs:CreateLogGroup",
"logs:CreateLogStream",
"logs:PutLogEvents"
],
"Resource": "arn:aws:logs:*:*:*"
},
{
"Effect": "Allow",
"Action": [ "ec2:DescribeImages" ],
"Resource": "*"
}
]
}
Use a CloudFormation Parameter to define the pattern to match against when
searching for the AMI by Name. In the example below, the default value of the
parameter AmiNameStringSearch
is set to match the naming pattern Amazon uses
for their Windows Server 2012 R2 AMIs.
"Parameters" : {
"AmiNameSearchString" : {
"Description" : "Search pattern to match against an AMI Name",
"Type" : "String",
"Default" : "Windows_Server-2012-R2_RTM-English-64Bit-Base-*"
}
}
Call the Lambda function using a custom CloudFormation resource. This resource
will return with an attribute named Id
containing the AMI ID. Use the
function Fn::GetAtt
to reference this attribute within the ImageId
property of the instance (or launch configuration).
"Resources" : {
"AmiIdLookup": {
"Type": "Custom::AmiIdLookup",
"Properties": {
"ServiceToken": {
"Fn::Join" : [
":",
[
"arn:aws:lambda",
{ "Ref" : "AWS::Region" },
{ "Ref" : "AWS::AccountId" },
"function:cfn-look-up-ami-ids"
]
]
},
"Region": { "Ref" : "AWS::Region" },
"AmiNameSearchString": { "Ref" : "AmiNameSearchString" }
}
},
"MyInstance" :
{
"Type" : "AWS::EC2::Instance",
"Properties" : {
"ImageId": { "Fn::GetAtt": [ "AmiIdLookup", "Id" ] },
# ... elided ...
}
}
}