Revert "Make it possible to have additional DNS names for Postfix"

This reverts commit 1c0a2a7.  It causes the
certificate to change at every container restart, which effectively disconnects
clients.

Author: bronger

Dockerfile

@@ -64,7 +64,11 @@ RUN mkdir /etc/sigh
 COPY sigh.cfg /etc/sigh/
 RUN mkdir "$SIGH_ROOT"; chown filter "$SIGH_ROOT"
 
-COPY csr.conf /opt/
+COPY csr.conf /tmp
+RUN openssl req -x509 -days 3650 -key /etc/ssl/private/ssl-cert-snakeoil.key \
+        -out /etc/ssl/certs/ssl-cert-snakeoil-postfix.pem -config /tmp/csr.conf -extensions v3_req && \
+    rm /tmp/csr.conf
+RUN openssl x509 -in /etc/ssl/certs/ssl-cert-snakeoil-postfix.pem -text
 
 RUN postconf -e "smtp_sasl_auth_enable=yes" && \
     postconf -e "smtp_tls_security_level=may" && \

README.rst

@@ -48,11 +48,6 @@ There are five environment variables:
   Defaults to ``postfix sigh``, i.e. both.  Mind to quote it properly,
   depending on context.
 
-``POSTFIX_EXTRA_DNS_NAMES``
-  Space-separated list of additional DNS names for the self-signed certificate
-  for Postfix.  “postfix” is always set, but by using this environment
-  variable, you can add e.g. ``postfix.default.svc.cluster.local``.
-
 
 So, for example, you could say::
 
@@ -113,8 +108,6 @@ this:
                   value: …
                 - name: TZ
                   value: …
-                - name: POSTFIX_EXTRA_DNS_NAMES
-                  value: postfix.default.svc.cluster.local
             - name: sigh
               image: bronger/postfix
               command: [/opt/entrypoints/entrypoint-sigh.sh]

csr.conf

@@ -6,4 +6,4 @@ CN = localhost
 [v3_req]
 subjectAltName = @alt_names
 [alt_names]
-DNS.1 = postfix
+DNS = postfix

entrypoints/configure-common.sh

@@ -7,14 +7,3 @@ echo "$TZ" > /etc/timezone
 
 : "${LOG_OUTPUT:=sigh postfix}"
 export LOG_OUTPUT
-
-index=2
-for name in $POSTFIX_EXTRA_DNS_NAMES
-do
-    printf "DNS.%d = %s\n" $index "$name" >> /opt/csr.conf
-    index=$((index+1))
-done
-
-openssl req -x509 -days 3650 -key /etc/ssl/private/ssl-cert-snakeoil.key \
-        -out /etc/ssl/certs/ssl-cert-snakeoil-postfix.pem -config /opt/csr.conf -extensions v3_req
-openssl x509 -in /etc/ssl/certs/ssl-cert-snakeoil-postfix.pem -text