Sometimes it’s necessary to get the difference between two branches. Git already provides a really powerful diff command which does exactly this:
git diff
git diff is very powerful, as it not only compares two branches, it also allows multiple comparisons:
Show changes between the working tree and the index or a tree, changes between the index and a tree, changes between two trees, changes resulting from a merge, changes between two blob objects, or changes between two files on disk.
Sometimes it’s necessary to trigger an action for CI/CD, e.g. when you use GitLab. To do this without any changes on the code base, you can create an empty commit. For this, git has a command:
The setup described in this post has been tested on the following system:
DS216+II with 8GB RAM
DSM 6.2.3-25426 Update 2
In addition, the following software packages have already been installed on the system using the Synology package manager:
Docker 18.09.0-0513
GitLab is installed via the Docker Registry:
gitlab/gitlab-ce:latest (in my case GitLab 13.5.1-ce.0)
Install GitLab
You can skip this part, if GitLab is already running on your Synology and continue with the step Install GitLab Runner.
To install GitLab, open the Docker Registry and search for “gitlab”. Double click the entry gitlab/gitlab-ce:latest and select the latest version:
After the image is loaded, it will be listed under image. Launch this image and set the folders to be mounted as shown in the following image. This will simplify the access to the docker files within your Synology.
Mounted folder / volumes
Port settings
The port settings depend on your system. Normally, HTTP is accessible at port 80 or HTTPS on port 443. If your system already uses other apps that are running on those port, you can adjust them in Port Settings.
After completing the setup, it might take some time until the GitLab web surface is available. When accessing GitLab for the first time, you can specify a password for the root environment. The default username for the admin area is root. Now you can create user accounts, projects and perform any adjustments that fit your needs.
Install GitLab Runner
As the Synology DSM uses Docker to run GitLab, we can use Docker as well to install GitLab Runner. For this, connect to the Synology using SSH:
ssh <admin-user>@<synology> -p <port>
Now we can install the Gitlab Runner Docker container that can run other Docker containers to perform the runner tasks:
This will install a Docker container with the name gitlab_runner_docker which uses the same network as Docker (‘–network host‘).
As this container is the basis for our Docker-in-Docker setup, we connect the Docker socket of our main container to the new one by using -v /run/docker.sock:/var/run/docker.sock.
You might also use the Docker GUI of DSM to create the container. But the step above can only be done with the help of the console command!
To test the container, you can use the following command to connect to the console:
Runtime platform arch=amd64 os=linux pid=16 revision=e95f89a0 version=13.4.1
Running in system-mode.
Please enter the gitlab-ci coordinator URL (e.g. https://gitlab.com/):
http://10.0.6.102:30000/
Please enter the gitlab-ci token for this runner:
ab1234abcd1234abcd12
Please enter the gitlab-ci description for this runner:
[synology]: docker_alpine
Please enter the gitlab-ci tags for this runner (comma separated):
Registering runner... succeeded runner=sA4DKorC
Please enter the executor: docker-ssh, parallels, docker+machine, kubernetes, docker, shell, ssh, virtualbox, docker-ssh+machine, custom:
docker
Please enter the default Docker image (e.g. ruby:2.6):
alpine:latest
Runner registered successfully. Feel free to start it, but if it's running already the config should be automatically reloaded!
In this case, the executor docker and the base image alpine:latest is used for this container.
If you use a self-signed certificate for GItLab, then you have to specify the certificate with the option --tls-ca-file during registration:
Let’s connect to the bash terminal of this container to change some settings:
docker exec -it gitlab_runner_docker /bin/bash
The created Docker container is an alpine base system without any packages installed. To perform the changes, we need a simple terminal text editor like nano or vim. The following commands will install nano for this task:
apt-get update
apt-get install nano
Now you can use nano to edit the GitLab Runner config file:
nano /etc/gitlab-runner/config.toml
And add the following lines as highlighted in the config file below:
That’s it. Now you can use this GitLab Runner for your repositories and run jobs by using other Docker containers.
Example usage in .gitlab-ci.yml
The following example uses a php container to run tests for a simple PHP application and deploy the code to a server. Some of the settings depend on the setup of your PHP application, so the example will not work out of the box. But it can give you a good idea of what is possible.
# https://hub.docker.com/_/php
image: php:7.4-fpm
services:
- mysql:5.7
variables:
# Configure mysql environment variables (https://hub.docker.com/_/mysql/)
MYSQL_USER: $MYSQL_USER
MYSQL_PASSWORD: $MYSQL_PASSWORD
before_script:
# Initialize database, etc
stages:
- test
- deploy
test:
stage: test
script:
- composer install
- composer phpunit
deploy_production:
stage: deploy
environment:
name: production
url: https://www.example.com
script:
# run on server 'git checkout master && git pull origin master && exit'
only:
- master
Um den bei vielen Linux und Unix Installationen und Tools (wie bspw. git) standardmäßig genutzten VI Editor zu beenden muss man mit der “ESC”-Taste in den Kommandomodus wechseln (am besten mehrfach drücken um ggf. schon eingegeben Kommandos abzubrechen). Und dort dann
> :q
eingeben und Enter drücken. Dies beendet VIM wenn vorher nichts geändert wurde.
Wurde etwas am Text der geöffneten Datei geändert und man will dies speichern so nutzt man den Befehl:
> :wq
Will man die Änderungen verwerfen und VI verlassen, so hilft:
> :q!
Ein sehr hilfreiches und detailliertes Cheat Sheet zum Nachschlagen selten benutzter Befehle findet sich unter: https://devhints.io/vim
Kurz gesagt: git pull führt ein git fetch und anschließend ein git merge aus.
Ein git fetch kann man zu jeder Zeit machen, um die lokalen Branches zu aktualisieren und mit den entfernten Branches (origin, remote) abzugleichen. Diese Operation ändert dabei keine lokalen Branches, sie zeigt lediglich an, wenn Änderungen verfügbar sind. Man kann git fetch also bedenkenlos ausführen, ohne die lokale Arbeitskopie zu ändern.
Ein git pull führt ein git fetch und anschließend ein git merge aus. git pull wird dabei immer in den aktuellen Branch der Arbeitskopie mergen. Man wählt sich also den Branch aus, von dem man pullen möchte und pullt diesen (überführt dessen Änderungen) in den aktuellen Branch.
Ein git pull ist das, was man tun muss, um einen lokalen Branch auf den Stand des dazugehörigen entfernten Branch zu bringen.