Add support for managing LetsEncrypt certificates

Add support for managing LetsEncrypt certificates. The webgateway_getssl
service uses supervisor to run 3 processes: Apache HTTP Server, cron,
and busybox syslogd to aid in logging for cron. It also includes getssl
for requesting and renewing certificates. The renewal is run once a day
using cron. The updated Traefik configuration allows the certificates to
be read from the mounted volume and it watches for changes so the
certificates can be updated on the fly.

comanage-registry-getssl/Dockerfile

@@ -0,0 +1,36 @@
+FROM httpd:2.4.41
+
+RUN apt-get update && apt-get install -y --no-install-recommends \
+        busybox-syslogd \
+        ca-certificates \
+        coreutils \
+        cron  \
+        curl \
+        dnsutils \
+        gawk \
+        grep \
+        openssl \
+        sed \
+        ssl-cert \
+        supervisor \
+    && cp /etc/ssl/certs/ssl-cert-snakeoil.pem /usr/local/apache2/conf/server.crt \
+    && cp /etc/ssl/private/ssl-cert-snakeoil.key /usr/local/apache2/conf/server.key
+
+COPY httpd.conf /usr/local/apache2/conf/httpd.conf
+
+ENV GETSSL_SRC_URL=https://raw.githubusercontent.com/srvrco/getssl/master/getssl
+ENV GETSSL_EXEC=/usr/local/bin/getssl
+ENV GETSSL_WORKDIR=/opt/getssl
+
+RUN curl --silent ${GETSSL_SRC_URL} > ${GETSSL_EXEC} \
+    && chmod 700 ${GETSSL_EXEC} \
+    && mkdir -p ${GETSSL_WORKDIR} \
+    && mkdir -p /usr/local/apache2/htdocs/.well-known/acme-challenge
+
+COPY --chown=root:root root-crontab /etc/crontab
+
+RUN touch /etc/default/locale
+
+COPY supervisord.conf /usr/local/etc/supervisord.conf
+
+ENTRYPOINT ["/usr/bin/supervisord", "-c", "/usr/local/etc/supervisord.conf"]