docker

Deployement with Docker

There are many ways to deploy this solution with Docker: docker alone, docker-compose, or docker swarm. Here I describe deployment with docker swarm.

Pre-requisite

• Docker and Docker Swarm

While Docker Swarm is not strictly required, I recommend it for support of docker secrets. This avoids to store your SMTP password in clear on your docker host. If you have docker running without Swarm, just run docker swarm init (full documentation here). You can also check if your docker host is already in Swarm mode with docker info.

Setup your SMTP password

This command requires Docker Swarm.

printf "your password" | docker secret create smtp_password -

Clone repository and setup docker-compose

Strictly speaking, you do not need to clone this entire repository. You'll just need:

• /src/docker-compose-example.yml
• /var/appsettings.json

So you can clone this repository or just download aforementioned files.

• Update var/appsettings.json as needed. Note docker-compose-example.yml overrides SmtpForwarder__Authentication__PasswordFile so you don't have to store your SMTP password in clear, and you can ignore this setting in appsettings.json file.
• Copy docker-compose-example.yml to docker-compose.yml
• Update docker-compose.yml as needed:
  • By default, example file assumes container will join an overlay network named my-attachable-overlay (overlay network and not bridge network to be compatible with docker swarm). You can adapt this (or you can create this network with command docker network create -d overlay --attachable my-attachable-overlay).

If you prefer not to use docker secrets, you can set your SMTP password in clear in docker-compose.yml by replacing SmtpForwarder__Authentication__PasswordFile by SmtpForwarder__Authentication__Password (value is password in clear). Alternatively you can set password directly in appsettings.json.

Run it

From directory containing docker-compose.yml:

docker stack deploy -c docker-compose.yml localsmtprelay

If you need to stop it:

docker stack rm localsmtprelay

Configure your local SMTP clients:

• From another container on same docker host: use hostname localsmtprelay and port 25.
• From docker host: use localhost and port binding set in docker-compose.yml (default: port 25).
• From another machine: use docker host IP address.

Update version

You don't need to stop current deployment.

• Update file docker-compose.yml to reflect new version of image field.
• Deploy or update with docker stack deploy -c docker-compose.yml localsmtprelay