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CentOS 7 yum HTTPS upgrade

This guide aims to help in pinning down the repository location to a known FQDN, so it can be set in the allowlists, without affecting the performance of downloads.

Virtual Machine​

AWS User Data​

#!/bin/bash -ex
sed --in-place=.orig --regexp-extended 's%#baseurl=http://mirror.centos.org/centos/%baseurl=https://mirrors.edge.kernel.org/centos/%g' /etc/yum.repos.d/CentOS-*.repo
sed --in-place --regexp-extended 's%^mirrorlist=%#mirrorlist=%g' /etc/yum.repos.d/CentOS-*.repo

The commands simply replace CentOS's default mirror redirector with a known, reliable CDN, making a backup file (with extension .orig) in the process.

GCP Startup Script​

#!/bin/bash -ex
# centos
sed --in-place=.orig --regexp-extended 's%#baseurl=http://mirror.centos.org/centos/%baseurl=https://mirrors.edge.kernel.org/centos/%g' /etc/yum.repos.d/CentOS-*.repo
sed --in-place --regexp-extended 's%^mirrorlist=%#mirrorlist=%g' /etc/yum.repos.d/CentOS-*.repo
# epel
sed --in-place=.orig --regexp-extended 's%#baseurl=http://(download.example|download.fedoraproject.org)/pub/epel/%baseurl=https://mirrors.edge.kernel.org/fedora-epel/%g' /etc/yum.repos.d/epel*.repo
sed --in-place --regexp-extended 's%^metalink=%#metalink=%g' /etc/yum.repos.d/epel*.repo

The first set of commands simply replace CentOS's default mirror redirector with a known, reliable CDN, making a backup file (with extension .orig) in the process.

The second set of commands simply replace Fedora's default mirror redirector with a known, reliable CDN, making a backup file (with extension .orig) in the process.

Container​

Dockerfile​

FROM centos:7

RUN sed --in-place=.orig --regexp-extended 's%#baseurl=http://mirror.centos.org/centos/%baseurl=https://mirrors.edge.kernel.org/centos/%g' /etc/yum.repos.d/CentOS-*.repo && \
    sed --in-place --regexp-extended 's%^mirrorlist=%#mirrorlist=%g' /etc/yum.repos.d/CentOS-*.repo && \
    yum clean expire-cache

Allowlist​

FQDNs​

mirrors.edge.kernel.org

DiscrimiNAT Annotation​

discriminat:tls:mirrors.edge.kernel.org

Alternative Mirrors​

Although mirrors.edge.kernel.org is a CDN with geo-located caches, you may want to pick a specific https mirror from CentOS's official mirrors list.