For S3-Logs Extension Demo using .zip archive the makefile name should be corrected to Makefile instead of makefile, otherwise the commmand sam build will fail with error
Makefile not found at /../aws-lambda-extensions/s3-logs-extension-demo-zip-archive/extensionssrc/Makefile
For S3-Logs Extension Demo using .zip archive the makefile name should be corrected to Makefile instead of makefile, otherwise the commmand sam build will fail with error Makefile not found at /../aws-lambda-extensions/s3-logs-extension-demo-zip-archive/extensionssrc/Makefile