delayed_job in rails docker is not working properly

Question

I have shifted my rails application to docker. Everything is working fine except the rails delayed_job. I have use delayed_job to send email. I have started my job through command docker-compose run web rake jobs:work it has started succesfully as shown in the image.

Now when I am trying to send email in console it is showing that the email is initiated as shown in the above image.

Do I have to include any line in my docker-compose.yml or Dockerfile.

My Dockerfile is :

FROM ruby:2.3.6

RUN mkdir -p /railsapp
WORKDIR /railsapp

RUN apt-get update && apt-get install -y nodejs --no-install-recommends
RUN apt-get update && apt-get install -y mysql-client  --no-install-recommends

COPY Gemfile /railsapp/

COPY Gemfile.lock /railsapp/


RUN bundle install

COPY . /railsapp

EXPOSE 3000
CMD ["rails", "server", "-b", "0.0.0.0"]

My docker-compose.yml is :

  version: '3.3'

  services:
    mysql:
      image: mysql
      restart: always
      ports:
        - "3002:3002"
      volumes:
        - /var/lib/mysql
      environment:
        - MYSQL_ROOT_PASSWORD=root
        - MYSQL_DATABASE=dev

    web:
      build: .
      environment:
        - RAILS_ENV=development
      ports:
        - '3000:3000'
      volumes:
        - .:/railsapp
      links:
        - "mysql"
      depends_on:
        - mysql

I am completely new to docker.

Answer 1

I am not sure how you have configured your ActionMailer, but if you are using default settings, you are probably sending e-mail via your servers built-in Mail Transfer Agent. In practice, this means that Rails invokes a system command called sendmail which accepts the outgoing e-mail and puts it in a local queue to be picked up by a service/daemon called postfix. Unless you have explicitly enabled it, Postfix is not running inside your Docker container and your e-mails are not going anywhere.

You can see an example of sendmail here: https://help.dreamhost.com/hc/en-us/articles/216687518-How-do-I-use-Sendmail-

You have two options.

1) Enable Postfix inside your Delayed Job container. This involves finding out which OS package to install and which daemon/service to run.

2) Switch to an external SaaS mailing service such as Sendgrid or Mailgun. These services expose REST or SOAP API's which ActionMailer can call directly to ship a particular e-mail. This eliminates the needs to host your own postfix server. In addition, these third party services are specialized in correct delivery, which reduces the risk of your e-mails inadvertedly going into the recipients spam folder. I recommend this approach.