Out of memory error in 'Composer update' command inside docker container in Aws ec2 instance

I have tried to run 'composer update' command inside docker container in Aws ec2 instance. But I get this error

  mmap() failed: [12] Cannot allocate memory  mmap() failed: [12] Cannot allocate memory  Fatal error: Out of memory (allocated 478179328) (tried to allocate 20996408 bytes) in phar:///usr/local/bin/composer/src/Composer/Util/RemoteFilesystem.php on line 462

I have tried using "memory_limit = -1" or "memory_limit = 2G" in the php configaration file.I have also tried to run this command "php -d memory_limit=-1 /usr/local/bin/composer update" inside my docker container.But it still shows the same error