Laravel で Cannot allocate memory がでたときの対策

VPS で、Laravel の次の操作を行うとエラーが出ました。

composer require league/flysystem-aws-s3-v3

エラーメッセージ

The following exception is caused by a lack of memory or swap, or not having swa
p configured
Check https://getcomposer.org/doc/articles/troubleshooting.md#proc-open-fork-fai
led-errors for details

                                                     
  [ErrorException]                                   
  proc_open(): fork failed - Cannot allocate memory

次のページに対策があります。
proc_open(): fork failed errors

1. Swap を確認

$ free -m
              total        used        free      shared  buff/cache   available
Mem:            983         159         705           3         119         691
Swap:             0           0           0

1. Swap を作成

$ sudo /bin/dd if=/dev/zero of=/var/swap.1 bs=1M count=1024
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB, 1.0 GiB) copied, 13.3311 s, 80.5 MB/s

$ sudo /sbin/mkswap /var/swap.1
mkswap: /var/swap.1: insecure permissions 0644, 0600 suggested.
Setting up swapspace version 1, size = 1024 MiB (1073737728 bytes)
no label, UUID=7e8e5b8d-436b-49e0-a9e0-7998b24f8679

$ sudo /sbin/swapon /var/swap.1
swapon: /var/swap.1: insecure permissions 0644, 0600 suggested.

1. Swap を確認

$ free -m
              total        used        free      shared  buff/cache   available
Mem:            983         159          67           3         757         672
Swap:          1023           0        1023