python - boto3 client NoRegionError: You must specify a region error only sometimes

Question

I have a boto3 client :

boto3.client('kms')

But it happens on new machines, They open and close dynamically.

    if endpoint is None:
        if region_name is None:
            # Raise a more specific error message that will give
            # better guidance to the user what needs to happen.
            raise NoRegionError()

Why is this happening? and why only part of the time?

Answer 1

One way or another you must tell boto3 in which region you wish the kms client to be created. This could be done explicitly using the region_name parameter as in:

kms = boto3.client('kms', region_name='us-west-2')

or you can have a default region associated with your profile in your ~/.aws/config file as in:

[default]
region=us-west-2

or you can use an environment variable as in:

export AWS_DEFAULT_REGION=us-west-2

but you do need to tell boto3 which region to use.

Answer 2

os.environ['AWS_DEFAULT_REGION'] = 'your_region_name'

In my case sensitivity mattered.

Answer 3

For Python 2 I have found that the boto3 library does not source the region from the ~/.aws/config if the region is defined in a different profile to default. So you have to define it in the session creation.

session = boto3.Session(
    profile_name='NotDefault',
    region_name='ap-southeast-2'
)

print(session.available_profiles)

client = session.client(
    'ec2'
)

Where my ~/.aws/config file looks like this:

[default]
region=ap-southeast-2

[NotDefault]
region=ap-southeast-2

I do this because I use different profiles for different logins to AWS, Personal and Work.

Answer 4

I believe, by default, boto picks the region which is set in aws cli. You can run command #aws configure and press enter (it shows what creds you have set in aws cli with region)twice to confirm your region.

Answer 5

you can also set environment variables in the script itself, rather than passing region_name parameter

os.environ['AWS_DEFAULT_REGION'] = 'your_region_name'

case sensitivity may matter.

Answer 6

For those using CloudFormation template. You can set AWS_DEFAULT_REGION environment variable using UserData and AWS::Region. For example,

MyInstance1:
    Type: AWS::EC2::Instance                
    Properties:                           
        ImageId: ami-04b9e92b5572fa0d1 #ubuntu
        InstanceType: t2.micro
        UserData: 
            Fn::Base64: !Sub |
                    #!/bin/bash -x

                    echo "export AWS_DEFAULT_REGION=${AWS::Region}" >> /etc/profile

Answer 7

Alternatively you can run the following (aws cli)

aws configure --profile $PROFILE_NAME

it'll prompt you for the region.

notice in ~/.aws/config it's:

[default]
region = ap-southeast-1
output = json

[profile prod]
region = ap-southeast-1
output = json

[profile profile name] in the square brackets