Use vault.centos6

test/Dockerfile-centos6

@@ -5,8 +5,14 @@ FROM centos:centos6
 # [wsl2]
 # kernelCommandLine = vsyscall=emulate
 
+# Centos 6 is EOL and is no longer available from the usual mirrors, so switch
+# to https://vault.centos.org
+RUN sed -i 's/enabled=1/enabled=0/g' /etc/yum/pluginconf.d/fastestmirror.conf && \
+    sed -i 's/^mirrorlist/#mirrorlist/g' /etc/yum.repos.d/*.repo && \
+    sed -i 's;^#baseurl=http://mirror;baseurl=https://vault;g' /etc/yum.repos.d/*.repo
+
 # Update and install required software
-RUN yum -y update
+#RUN yum -y update
 RUN yum -y install epel-release
 RUN yum -y install git curl dnsutils ldns wget nginx