Thank you for your link, I got this working.
For others who are searching to fix this error, run the following in your docker container running Amazon AMI (I used docker image dacut/amazon-linux-python-3.6, it should be the same in ec2 or any Amazon Linux)
Only needed during first-time setup:
wget http://packages.couchbase.com/releases/couchbase-release/couchbase-release-1.0-4-x86_64.rpm
sudo rpm -iv couchbase-release-1.0-4-x86_64.rpm
Will install or upgrade existing packages
sudo yum install libcouchbase-devel libcouchbase2-bin gcc gcc-c++
Then include the files in
/usr/include/libcouchbase
and the .so files in
/usr/lib64/libcouchbase.so
/usr/lib64/libcouchbase.so.2
/usr/lib64/libcouchbase.so.2.0.51
in your lambda deployment package zip file which you will be uploading to S3.
(if you cannot for some reason find the files in /usr/lib64, use this command to check where the files are located - bash-4.2#rpm -ql libcouchbase-devel libcouchbase2-bin )