eC2上のAmazon Linux 2のpostgres 9.6 rpmのyumインストールは、依存関係/ etc/redhat-releaseが原因で失敗します
以下はログです
Sudo yum install https://download.postgresql.org/pub/repos/yum/9.6/redhat/rhel-7-x86_64/pgdg-centos96-9.6-3.noarch.rpm
Loaded plugins: extras_suggestions, langpacks, priorities, update-motd
pgdg-centos96-9.6-3.noarch.rpm | 5.6 kB 00:00:00
Examining /var/tmp/yum-root-BrRLfO/pgdg-centos96-9.6-3.noarch.rpm: pgdg-redhat-repo-42.0-4.noarch
Marking /var/tmp/yum-root-BrRLfO/pgdg-centos96-9.6-3.noarch.rpm to be installed
Resolving Dependencies
--> Running transaction check
---> Package pgdg-redhat-repo.noarch 0:42.0-4 will be installed
--> Processing Dependency: /etc/redhat-release for package: pgdg-redhat-repo-42.0-4.noarch amzn2-core | 2.4 kB 00:00:00
--> Processing Dependency: /etc/redhat-release for package: pgdg-redhat-repo-42.0-4.noarch
--> Finished Dependency Resolution
Error: Package: pgdg-redhat-repo-42.0-4.noarch (/pgdg-centos96-9.6-3.noarch)
Requires: /etc/redhat-release
Sudo Amazon-linux-extras
をお試しください
Amazonには専用チャネルがあります
https://aws.Amazon.com/Amazon-linux-2/faqs/#Amazon_Linux_Extras