allow to set dynamic variables per mail template

directly used in the new fooled-friday template

Dockerfile

@@ -6,27 +6,26 @@
 FROM bitnami/minideb:bullseye
 
 # Installing the services and dependencies
-RUN install_packages msmtp ca-certificates curl
+RUN install_packages msmtp ca-certificates curl gettext-base
 
 # Manually install supercronic
 ENV SUPERCRONIC_URL=https://github.com/aptible/supercronic/releases/download/v0.1.12/supercronic-linux-amd64 \
     SUPERCRONIC=supercronic-linux-amd64 \
     SUPERCRONIC_SHA1SUM=048b95b48b708983effb2e5c935a1ef8483d9e3e
-
 RUN curl -fsSLO "$SUPERCRONIC_URL" \
  && echo "${SUPERCRONIC_SHA1SUM}  ${SUPERCRONIC}" | sha1sum -c - \
  && chmod +x "$SUPERCRONIC" \
  && mv "$SUPERCRONIC" "/usr/local/bin/${SUPERCRONIC}" \
  && ln -s "/usr/local/bin/${SUPERCRONIC}" /usr/local/bin/supercronic
 
+# Set up unprivileged user
 RUN adduser --shell "/sbin/nologin" --gecos "Reminder" --disabled-password reminder
-
 USER reminder
-
 WORKDIR /home/reminder
 
-RUN mkdir mails
+# Add script and mails
 COPY reminder-mails.sh cron.txt .msmtprc /home/reminder/
+RUN mkdir mails
 COPY mails/* /home/reminder/mails/
 
 # CMD to run the cron on container start

cron.txt

@@ -2,6 +2,7 @@
 #
 # SPDX-License-Identifier: CC0-1.0
 
-0 22 15 2,5,8,11 *  /home/reminder/reminder-mails.sh access-review
-0 22 15 1,4,7,10 *  /home/reminder/reminder-mails.sh services-review
-0 22 15 3,6,9,12 *  /home/reminder/reminder-mails.sh mailinglist-review
+0 22 15 2,5,8,11 *  /home/reminder/reminder-mails.sh /home/reminder/mails/access-review
+0 22 15 1,4,7,10 *  /home/reminder/reminder-mails.sh /home/reminder/mails/services-review
+0 22 15 3,6,9,12 *  /home/reminder/reminder-mails.sh /home/reminder/mails/mailinglist-review
+* * * * *           /home/reminder/reminder-mails.sh /home/reminder/mails/fooled-friday

mails/fooled-friday

@@ -0,0 +1,24 @@
+# Set a random recipient based on the array $users
+# var: users=("alex.sander@fsfe.org" "bonnie@fsfe.org" "eal@fsfe.org" "fani@fsfe.org" "gabriel.ku@fsfe.org" "jackie@fsfe.org" "lina.ceballos@fsfe.org" "linda@fsfe.org" "linus@fsfe.org" "lucas.lasota@fsfe.org" "max.mehl@fsfe.org" "mk@fsfe.org" "niharika@fsfe.org")
+# var: to=${users[$RANDOM % ${#users[@]}]}
+To: $to
+From: no-reply@fsfe.org
+Subject: [Staff] You have been chosen for Fooled Friday!
+
+Hello,
+
+You have been selected the random person of the group to say one wrong task in
+the daily meeting that you have done or will do. Nobody except you knows that
+you are the one who is supposed to trick the others, so keep it secret!
+
+Others than have to guess who of the group tries to trick them, and detect the
+wrong task.
+
+Good luck and have fun :)
+
+Best,
+Your friendly randomiser robot
+
+--
+This mail has been automatically sent by:
+https://git.fsfe.org/fsfe-system-hackers/reminder-mails

reminder-mails.sh

@@ -10,26 +10,49 @@
 prepmail () {
   # read mail in variable
   mail=$(< "$1")
-  # add date and message ID
-  mail=$(echo "$mail" | sed "1s|^|Date: $(date -R)\n|" | sed "1s|^|Message-ID: <ReMiNdEr.$(date +%s)@fsfe.org>\n|")
 
-  echo "$mail"
+  # get dynamic variables from file
+  while read -r line; do
+    if [[ -n "$line" ]]; then
+      # remove prefix
+      line=${line//# var: /}
+      # export the line in the format of var=value
+      eval "export $line"
+    fi
+  done <<< "$(grep '^# var: ' <<< "$mail")"
+
+  # add date and message ID in the first lines
+  # and remove all local variable declaration from template
+  mail=$(echo "$mail" | sed "1s|^|Date: $(date -R)\n|" \
+                      | sed "1s|^|Message-ID: <ReMiNdEr.$(date +%s)@fsfe.org>\n|" \
+                      | sed '/^#.*/d')
+
+  # replace variables in mail with exported variables
+  envsubst <<< "$mail"
+}
+
+send_mail() {
+  if [[ "$DEBUG" != "debug" ]]; then
+    msmtp -t --read-envelope-from -a fsfe
+  else
+    cat
+  fi
 }
 
 EMAIL=$1
+DEBUG=$2
 
 # If argument is given, check for mail template and send it out
-if [[ ! -z "$EMAIL" ]]; then
-  if [[ -e "${HOME}/mails/$EMAIL" ]]; then
-    prepmail "$EMAIL" | msmtp -t --read-envelope-from -a fsfe
-    if [[ "$?" == 0 ]]; then
-      echo "[INFO] Mail \"$EMAIL\" has been sent successfully"
+if [[ -n "$EMAIL" ]]; then
+  if [[ -e "$EMAIL" ]]; then
+    if prepmail "$EMAIL" | send_mail; then
+      echo "[INFO] $EMAIL has been sent successfully"
     else
-      echo "[ERROR] There has been an error with sending \"$EMAIL\"".
+      echo "[ERROR] There has been an error with sending $EMAIL".
       exit 1
     fi
   else
-    echo "[ERROR] Mail template \"$EMAIL\" does not exist."
+    echo "[ERROR] Mail template $EMAIL does not exist."
     exit 1
   fi
 else