AWS CLI fatal error: An error occurred (SignatureDoesNotMatch) when calling the ListObjectsV2 operation

Cna you ever imagine that having + or / in your private AWS keys will cause an issue for you? Read on.

Working with AWS CLI v2

That happened to me on CI when I was implementing upload of the config files (you might think of some .json files) to the S3 bucket using official AWS CLI in Docker.

amazon/aws-cli is an identifier of the official amazon image from Docker Hub with the most updated version of AWS CLI installed. Find out more about available command of the CLI here amazon/aws-cli.

Everything was working well locally, well, you know "works on my machine"™ until on CI. I used amazon/aws-cli s3 sync command and checked uploaded files via Cyberduck.

amazon/aws-cli s3 sync --delete /app/some-app s3://my-bucket-some-app

When I created GitLab CI/CD pipeline to do the same on the CI the job is suddenly failed.

fatal error: An error occurred (SignatureDoesNotMatch) when calling the ListObjectsV2 operation

You might think huh… what? Having + or / characters in your AWS credentials might break your interaction with AWS CLI

Yeah, I know... so stupid but this issue exists for 6 years already. Read more about it on the official amazon/aws-cli Github repo: SignatureDoesNotMatch error #602.

It took me some time to convince Lead DevOps that this is a real issue with secret keys...

fatal error: An error occurred (SignatureDoesNotMatch) when calling the ListObjectsV2 operation: The request signature we calculated does not match the signature you provided. Check your key and signing method.

From what I read in the issue it usually fails on CI (CircleCI and so on). From the issue description:

This has to be one of the most frustrating bugs I have encountered and it’s nuts that it hasn’t been fixed. Getting a cred without a “+” worked for me in CircleCI.

Solution

Re-generating secret keys worked like a charm and the job became green. So, be patient and check your secret keys first if you'll see this error around 😉

Conclusion

You might have a logical question why would AWS continue to generate secret keys with + or / knowing that this might potentially cause some issues? I don't know. I could imagine that AWS has so many tools and services that it is hard to follow and fix everything.