EC2へのlibsodiumのインストール

AWS Ec2（Linux）インスタンスにRおよび関連パッケージをインストールしようとしています。これらのパッケージはlibsodiumの依存関係のために失敗します。

R 失敗

    ------------------------- ANTICONF ERROR ---------------------------
Configuration failed because libsodium was not found. Try installing:
 * deb: libsodium-dev (Debian, Ubuntu, etc)
 * rpm: libsodium-devel (Fedora, EPEL)
 * csw: libsodium_dev (Solaris)
 * brew: libsodium (OSX)
If libsodium is already installed, check that 'pkg-config' is in your
PATH and PKG_CONFIG_PATH contains a libsodium.pc file. If pkg-config
is unavailable you can set INCLUDE_DIR and LIB_DIR manually via:
R CMD INSTALL --configure-vars='INCLUDE_DIR=... LIB_DIR=...'
--------------------------------------------------------------------

EC2にlibsodiumをインストールしてみてください

[ec2-user@ip-xxx R]$ sudo yum install libsodium
Loaded plugins: extras_suggestions, langpacks, priorities, update-motd
amzn2-core                                                                                                                                                                                  | 3.7 kB  00:00:00
No package libsodium available.
Error: Nothing to do

libsodium-develを提供する場合も同様です。

[ec2-user@ip-xxx R]$ yum info libsodium-devel
Loaded plugins: extras_suggestions, langpacks, priorities, update-motd
Error: No matching Packages to list

===編集====

提案通りここRHEL用のsudo yum install epel-release（EPEL）をインストールしようとしたら、amazon-extrasにリダイレクトされ、次のようにインストールしました。

ec2-user@ip-xxx R]$ sudo amazon-linux-extras install epel
Installing epel-release
Loaded plugins: extras_suggestions, langpacks, priorities, update-motd
Cleaning repos: amzn2-core amzn2extra-R3.4 amzn2extra-docker amzn2extra-epel
17 metadata files removed
6 sqlite files removed
0 metadata files removed
Loaded plugins: extras_suggestions, langpacks, priorities, update-motd
amzn2-core                                                                                                                                                                                  | 3.7 kB  00:00:00
amzn2extra-R3.4                                                                                                                                                                             | 3.0 kB  00:00:00
amzn2extra-docker                                                                                                                                                                           | 3.0 kB  00:00:00
amzn2extra-epel                                                                                                                                                                             | 3.0 kB  00:00:00
(1/9): 
:
(9/9): amzn2-core/2/x86_64/primary_db                                                                                                                                                       |  51 MB  00:00:00
Resolving Dependencies
--> Running transaction check
---> Package epel-release.noarch 0:7-11 will be installed
--> Finished Dependency Resolution

Dependencies Resolved

==========================================================================
 Package                                              Arch                                           Version                                         Repository                                               Size
==============================================================================
Installing:
 epel-release                                         noarch                                         7-11                                            amzn2extra-epel                                          15 k

Transaction Summary
===============================================================================
Install  1 Package

Total download size: 15 k
Installed size: 24 k
Is this ok [y/d/N]: y
Downloading packages:
epel-release-7-11.noarch.rpm                                                                                                                                                                |  15 kB  00:00:00
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction
  Installing : epel-release-7-11.noarch                                                                                                                                                                        1/1
  Verifying  : epel-release-7-11.noarch                                                                                                                                                                        1/1

Installed:
  epel-release.noarch 0:7-11

Complete!

しかし、まだ「libsodiumが見つかりません」というエラーが発生し、失敗します。

[ec2-user@ip-xxx R]$ sudo find / -iname libsodium [ec2-user@ip-xxx R]$

AWS EC2にlibsodiumをインストールする方法についてのアドバイスをお願いします。

挨拶。