Убрал лишнее, добавил необходимое

Dockerfile

@@ -1,16 +1,19 @@
 FROM centos:7.4.1708
 COPY nginx.repo /etc/yum.repos.d/nginx.repo
-ARG git_dir=pki
+
 RUN yum install -y epel-release \
     && yum install yum-utils python2-certbot-nginx openssl ca-certificates nginx -y \
     && yum install -y https://centos7.iuscommunity.org/ius-release.rpm \
     && yum install -y git2u \
+    && yum clean all \
+    && rm -rf /var/cache/yum \
     && mkdir -p /var/www/html/.well-known \
-    && mkdir -p /${git_dir} \
+    && touch /var/log/letsencrypt/letsencrypt.log \
+    && ln -sf /dev/stdout /var/log/letsencrypt/letsencrypt.log \
     && ln -sf /dev/stdout /var/log/nginx/access.log \
     && ln -sf /dev/stderr /var/log/nginx/error.log
-#COPY cli.ini /etc/letsencrypt/
+
 COPY default.conf /etc/nginx/conf.d/
-COPY ${git_dir}/letsencrypt/ /${git_dir}/letsencrypt/
+
 EXPOSE 80
 CMD ["nginx", "-g", "daemon off;"]

default.conf

@@ -1,10 +1,6 @@
 server {
 					listen 80;
-#        	location /.well-known/acme-challenge/ {
           location / {
             	root /var/www/html;
         	}
-#					location / {
-#		      		return 301 https://$host$request_uri;  # enforce https
-#					}
 }