Container

In our previous post Create a systemd service for your docker-compose project in 10 seconds we introduced a script that automatically creates a systemd service to start a docker-compose-based project. In this post, we’ll show

First, you need to create a file named backup.sh in the directory where docker-compose.yml is located. This file will be run by the systemd service every day. What that file contains is entirely up to you and we will provide examples in future blogposts.

Secondly, run

wget -qO- https://techoverflow.net/scripts/create-backup-service.sh | sudo bash /dev/stdin

from the directory where docker-compose.yml is located. Note that the script will use the directory name as a name for the service and timer that is created. For example, running the script in /var/lib/redmine-mydomain will cause redmine-mydomain-backup to be used a service name.

Example output from the script:

Creating systemd service... /etc/systemd/system/redmine-mydomain-backup.service
Creating systemd timer... /etc/systemd/system/redmine-mydomain-backup.timer
Enabling & starting redmine-mydomain-backup.timer
Created symlink /etc/systemd/system/timers.target.wants/redmine-mydomain-backup.timer → /etc/systemd/system/redmine-mydomain-backup.timer.

The script will create /etc/systemd/systemd/redmine-mydomain-backup.service containing the specification on what exactly to run:

[Unit]
Description=redmine-mydomain-backup

[Service]
Type=oneshot
ExecStart=/bin/bash backup.sh
WorkingDirectory=/var/lib/redmine-mydomain

and /etc/systemd/systemd/redmine-mydomain-backup.timer containing the logic when the .service is started:

[Unit]
Description=redmine-mydomain-backup

[Timer]
OnCalendar=daily
Persistent=true

[Install]
WantedBy=timers.target

and will automatically start and enable the timer. This means: no further steps are needed after running this script!

In order to show the current status of the service, use e.g.

sudo systemctl status redmine-mydomain-backup.timer

Example output:

● redmine-mydomain-backup.timer - redmine-mydomain-backup
     Loaded: loaded (/etc/systemd/system/redmine-mydomain-backup.timer; enabled; vendor preset: enabled)
     Active: active (waiting) since Thu 2020-12-10 02:50:31 CET; 19min ago
    Trigger: Fri 2020-12-11 00:00:00 CET; 20h left
   Triggers: ● redmine-mydomain-backup.service

Dec 10 02:50:31 myserverhostname systemd[1]: Started redmine-mydomain-backup.

In the

Trigger: Fri 2020-12-11 00:00:00 CET; 20h left

line you can see when the service will be run next. By default, the script generates tasks that run OnCalendar=daily, which means the service will be run on 00:00:00 every day. Checkout the systemd.time manpage for further information on the syntax you can use to specify other timeframes.

In order to run the backup immediately (it will still run daily after doing this), do

sudo systemctl start redmine-mydomain-backup.service

(note that you need to run systemctl start on the .service! Running systemctl start on the .timer will only enable the timer and not run the service immediately).

In order to view the logs, use

sudo journalctl -xfu redmine-mydomain-backup.service

(just like above, you need to run journalctl -xfu on the .service, not on the .timer).

In order to disable automatic backups, use e.g.

sudo systemctl disable redmine-mydomain-backup.timer

When using the offical gitlab Docker container, you can use this command to run psql:

docker exec -t -u gitlab-psql [container name] pg_dump -h /var/opt/gitlab/postgresql/ -d gitlabhq_production > gitlab-dump.sql

This will save the SQL dump of the database into gitlab-dump.sql

In case you’re using a docker-compose based setup, use this command:

docker-compose exec -u gitlab-psql gitlab pg_dump -h /var/opt/gitlab/postgresql/ -d gitlabhq_production > gitlab-dump.sql

Note that gitlab in this command is the container name.

Note: This config is currently missing a TURN server, so it won’t work if the clients can’t reach each other! I am working on this.

WebWormhole.io is a new service similar to and inspired by magic-wormhole that allows easily sharing files between browsers without the need to install a software. Internally, it uses WebRTC, allowing direct transfer of files between computers even through firewalls.

While there is no official Docker image published on Docker Hub, the WebWormhole GitHub project provides an official Dockerfile. Based on this, I have published ulikoehler/webwormhole which has been built using

git clone https://github.com/saljam/webwormhole.git
cd webwormhole
docker build -t ulikoehler/webwormhole:latest .
docker push ulikoehler/webwormhole:latest

This is the docker-compose.yml that you can use to run WebWormhole behind a reverse proxy:

version: '3'
services:
  webwormhole:
    image: 'ulikoehler/webwormhole:latest'
    entrypoint: ["/bin/ww", "server", "-http=localhost:52618", "-https="]
    network_mode: host

and this is my nginx config:

server {
    server_name  webwormhole.mydomain.com;

    access_log off;
    error_log /var/log/nginx/webwormhole.mydomain.com.error.log;

    location / {
        proxy_pass http://localhost:52618/;
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection "Upgrade";
        proxy_redirect default;
    }

    listen 443 ssl; # managed by Certbot
    ssl_certificate /etc/letsencrypt/live/webwormhole.mydomain.com/fullchain.pem; # managed by Certbot
    ssl_certificate_key /etc/letsencrypt/live/webwormhole.mydomain.com/privkey.pem; # managed by Certbot
    include /etc/letsencrypt/options-ssl-nginx.conf; # managed by Certbot
    #ssl_dhparam /etc/letsencrypt/ssl-dhparams.pem; # managed by Certbot
}
server {
    if ($host = webwormhole.mydomain.com) {
        return 301 https://$host$request_uri;
    }

    server_name webwormhole.mydomain.com;

    listen 80;
    return 404; # managed by Certbot
}

I store docker-compose.yml in /var/lib/webwormhole.mydomain.com and I used the script from our previous post Create a systemd service for your docker-compose project in 10 seconds in order to create this systemd config file in /etc/systemd/system/webwormhole.mydomain.com.service:

[Unit]
Description=webwormhole.mydomain.com
Requires=docker.service
After=docker.service

[Service]
Restart=always
User=root
Group=docker
WorkingDirectory=/var/lib/webwormhole.mydomain.com
# Shutdown container (if running) when unit is started
ExecStartPre=/usr/local/bin/docker-compose -f docker-compose.yml down
# Start container when unit is started
ExecStart=/usr/local/bin/docker-compose -f docker-compose.yml up
# Stop container when unit is stopped
ExecStop=/usr/local/bin/docker-compose -f docker-compose.yml down

[Install]
WantedBy=multi-user.target

which you can start and enable using

sudo systemctl enable webwormhole.mydomain.com
sudo systemctl start webwormhole.mydomain.com