Cronjob doesn't execute "bundle exec rake -f ..." - linux

Question

I am trying to automate redmine's issue creation via email within a docker container using cronjob.
I use a slightly modified version of the offical redmine docker image with cron installed and some additional environment variables.
Manually, when I run the following line in the terminal, everything works fine.
# cd /usr/src/redmine && bundle exec rake -f /usr/src/redmine/Rakefile redmine:email:receive_imap RAILS_ENV="production" host=$IMAP_HOST port=$IMAP_PORT ssl=1 username=$SMTP_USER password=$SMTP_PASSWORD -r "openssl" -E "OpenSSL::SSL::VERIFY_PEER = OpenSSL::SSL::VERIFY_NONE"
(eval):1: warning: already initialized constant OpenSSL::SSL::VERIFY_PEER
W, [2020-12-11T14:18:43.730617 #86] WARN -- : Creating scope :system. Overwriting existing method Enumeration.system.
W, [2020-12-11T14:18:45.264865 #86] WARN -- : Creating scope :sorted. Overwriting existing method Group.sorted.
W, [2020-12-11T14:18:45.273745 #86] WARN -- : Creating scope :sorted. Overwriting existing method User.sorted.
I, [2020-12-11T14:18:46.534306 #86] INFO -- : Performing ActionMailer::DeliveryJob (Job ID: eda80c3a-dc7d-4dcc-9fb9-ad25414cbad2) from Inline(mailers) with arguments: "Mailer", "issue_edit", "deliver_now", #<GlobalID:0x000055f759eb7818 #uri=#<URI::GID gid://redmine-app/User/1>>, #<GlobalID:0x000055f759eb6940 #uri=#<URI::GID gid://redmine-app/Journal/1>>
I, [2020-12-11T14:18:46.560561 #86] INFO -- : Rendering mailer/issue_edit.text.erb within layouts/mailer
I, [2020-12-11T14:18:46.597403 #86] INFO -- : Rendered mailer/_issue.text.erb (34.9ms)
I, [2020-12-11T14:18:46.597516 #86] INFO -- : Rendered mailer/issue_edit.text.erb within layouts/mailer (36.9ms)
I, [2020-12-11T14:18:46.600656 #86] INFO -- : Rendering mailer/issue_edit.html.erb within layouts/mailer
I, [2020-12-11T14:18:46.613771 #86] INFO -- : Rendered mailer/_issue.html.erb (0.9ms)
I, [2020-12-11T14:18:46.613876 #86] INFO -- : Rendered mailer/issue_edit.html.erb within layouts/mailer (13.1ms)
I, [2020-12-11T14:18:46.620620 #86] INFO -- : Performed ActionMailer::DeliveryJob (Job ID: eda80c3a-dc7d-4dcc-9fb9-ad25414cbad2) from Inline(mailers) in 86.17ms
I, [2020-12-11T14:18:46.621236 #86] INFO -- : Enqueued ActionMailer::DeliveryJob (Job ID: eda80c3a-dc7d-4dcc-9fb9-ad25414cbad2) to Inline(mailers) with arguments: "Mailer", "issue_edit", "deliver_now", #<GlobalID:0x000055f75a681d00 #uri=#<URI::GID gid://redmine-app/User/1>>, #<GlobalID:0x000055f75a681530 #uri=#<URI::GID gid://redmine-app/Journal/1>>
I, [2020-12-11T14:18:46.622072 #86] INFO -- : MailHandler: issue #1 updated by Redmine Admin
Now, I want to create a cronjob that executes this line, say every minute.
I added the cronjob below, but the desired outcome remains absent.
# crontab -l
* * * * * cd /usr/src/redmine && bundle exec rake -f /usr/src/redmine/Rakefile redmine:email:receive_imap RAILS_ENV="production" host=$IMAP_HOST port=$IMAP_PORT ssl=1 username=$SMTP_USER password=$SMTP_PASSWORD -r "openssl" -E "OpenSSL::SSL::VERIFY_PEER = OpenSSL::SSL::VERIFY_NONE"
From the /var/log/cron.log file I know, that the cronjob is executed.
Dec 11 14:43:01 26c0ec148cea CRON[155]: (root) CMD (cd /usr/src/redmine && bundle exec rake -f /usr/src/redmine/Rakefile redmine:email:receive_imap RAILS_ENV="production" host=$IMAP_HOST port=$IMAP_PORT ssl=1 username=$SMTP_USER password=$SMTP_PASSWORD -r "openssl" -E "OpenSSL::SSL::VERIFY_PEER = OpenSSL::SSL::VERIFY_NONE")
If I append &> /home/redmine/cron.log to the job, an empty file gets created.
I assume cron somehow breaks the command.
I already tried to use the full paths to bundle (/usr/local/bin/bundle) and rake (/usr/local/bundle/bin/rake) without success.
Can you help me to fix this cronjob or tell me how to debug this further?
Setup:
Dockerfile:
FROM redmine:latest
ENV SMTP_AUTHENTICATION="login" \
SMTP_DOMAIN="gmail.com" \
SMTP_HOST="smtp.gmail.com" \
SMTP_PASSWORD="<password>" \
SMTP_PORT="587" \
SMTP_TLS="true" \
SMTP_USER="<email>" \
IMAP_HOST="imap.gmail.com" \
IMAP_PORT="993"
RUN apt-get update > /dev/null && apt-get install -y cron vim rsyslog > /dev/null
RUN service rsyslog start
RUN crontab -l | { cat; echo '* * * * * cd /usr/src/redmine && bundle exec rake -f /usr/src/redmine/Rakefile redmine:email:receive_imap RAILS_ENV="production" host=$IMAP_HOST port=$IMAP_PORT ssl=1 username=$SMTP_USER password=$SMTP_PASSWORD -r "openssl" -E "OpenSSL::SSL::VERIFY_PEER = OpenSSL::SSL::VERIFY_NONE"'; } | crontab -
docker-compose.yml:
version: '3.1'
services:
redmine:
#image: redmine
build: '.'
restart: always
ports:
- 80:3000
volumes:
- 'redmine_data:/redmine'
environment:
REDMINE_DB_MYSQL: db
REDMINE_DB_PASSWORD: <password>
REDMINE_SECRET_KEY_BASE: <secretkey>
db:
image: mysql:5.7
restart: always
volumes:
- 'db_data:/db'
environment:
MYSQL_ROOT_PASSWORD: <password>
MYSQL_DATABASE: redmine
volumes:
db_data:
driver: local
redmine_data:
driver: local