Using Multiple AWS Regions with Pulumi and S3 Backend

For a while now, I’ve been using Direnv to manage environment variables when I enter or leave certain directories. Since I have to work with more than one AWS account, one of the use cases for me has been populating AWS-specific environment variables, like AWS_REGION or AWS_PROFILE. This generally works really well for me, but recently I ran into a bit of a corner case involving multiple AWS regions, Pulumi, and using S3 as the Pulumi backend. In this post, I’ll share the workaround that allows this configuration to work as expected.

I describe this as a “bit of a corner case” because it only affects specific configurations (which included my configuration):

• You must be setting the AWS_REGION environment variable and not setting the aws:region configuration value used by the Pulumi AWS provider.
• You must be using S3 as the backend for Pulumi, and using an S3 URL of s3://bucket-name.
• You want to deploy resources into an AWS region that is different than the AWS region where the backend state bucket resides.

In my specific situation, my backend state bucket resides in the AWS us-west-2 (Oregon) region, as this offers the lowest latencies from my home office in Colorado. I control this via the PULUMI_BACKEND_URL environment variable using the s3://bucket-name syntax. I needed to deploy resources into the us-east-2 (Ohio) region, so I set the AWS_REGION environment variable accordingly. Because I used AWS_REGION, I did not set the aws:region Pulumi provider configuration value.

When I ran pulumi stack init to create a Pulumi stack for the Ohio resources, I got an error message containing the text “incorrect region, the bucket is not in ‘us-east-2’ region at endpoint ‘’, bucket is in ‘us-west-2’ region”.

After a bit of Googling, I realized the problem: Pulumi was looking for the backend state bucket in the region specified by AWS_REGION. How, then, does one deploy to one AWS region when needing to use a backend state bucket in a different region?

The answer sits buried in this section of the Pulumi documentation; specifically, in this callout (emphasis mine):

As of Pulumi CLI v3.33.1, instead of specifying the AWS Profile, add awssdk=v2 along with the region and profile to the query string.

Ah ha! All that’s required is to amend the PULUMI_BACKEND_URL setting to look something more like this:

s3://bucket-name?region=us-west-2&awssdk=v2&profile=aws-profile

That worked perfectly—Pulumi now knew to look for the backend state bucket in the us-west-2 (Oregon) region while deploying resources to the region specified by the AWS_REGION environment variable. In theory, since I didn’t need to use different AWS profiles for the backend state bucket versus where resources live, it might be possible to remove &profile=aws-profile from the S3 URL. I haven’t tested that yet.

There you have it—to use different AWS regions for your S3 backend state bucket and the resources you’re deploying, make sure your PULUMI_BACKEND_URL setting properly includes the region in the URL as described above.

I hope this helps someone else out there! Hit me up on Twitter, on Mastodon, or on Bluesky if you have any feedback or any questions.

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