Version management

How to update git submodule to current master or other branch?

Let’s say you have a git submodule in MySubmodule directory. If you have made changes to the repository referred to by MySubmodule, you might want to update your project to refer to the latest commit.

In order to do this, simply go to the MySubmodule directory and run git pull there. You can also git checkout any other branch.

After that, you need to commit the changes (i.e. which commit git submodule is referring to currently) in the outer repository.

git status in the outer repository will show you the changes like this:

Changes not staged for commit:
  (use "git add <file>..." to update what will be committed)
  (use "git checkout -- <file>..." to discard changes in working directory)

        modified:   MySubmodule (new commits)

Use git add MySubmodule and git commit normally, or use git commit -a to commit all staged changes.

Posted by Uli Köhler in git, Version management

How to fix git ‘error: cannot open .git/FETCH_HEAD: Permission denied’

Problem:

You want to run git pull or some other git command but you only see this error message:

error: cannot open .git/FETCH_HEAD: Permission denied

Solution:

This means that the .git directory is not owned by you. The easiest way to fix that is to change the owner of the directory to your user.

First, go to the root directory of the repository using cd, if you are not already there.

Then,

sudo chown -R $USER: .

In case you don’t have sudo access on that computer, the easiest way is to copy the repository to a directory where you have write access (e.g. using cp -r) or even clone the repository again.

Posted by Uli Köhler in git, Version management

Running Gitlab CE via docker behind a reverse proxy on Ubuntu

Similarly to my previous article about installing Redmine via docker behind a reverse proxy, this article details. Since I am running an instance of Redmine and an instance of Gitlab on the same virtual server, plus tens of other services.

While the Gitlab CE docker container is nicely preconfigured for standalone use on a dedicated VPS, running it behind a reverse proxy is not supported and will lead to a multitude of error messages – in effect, requiring lots of extra work to get up and running.

Note that we will not setup GitLab for SSH access. This is possible using this setup, but usually makes more trouble than it is worth. See this article on how to store git https passwords so you don’t have to enter your password every time.

Installing Docker & Docker-Compose

# Install prerequisites
sudo apt-get update
sudo apt-get -y install apt-transport-https ca-certificates curl software-properties-common
# Add docker's package signing key
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -
# Add repository
sudo add-apt-repository -y "deb [arch=amd64] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable"
# Install latest stable docker stable version
sudo apt-get update
sudo apt-get -y install docker-ce
# Install docker-compose
sudo curl -L "https://github.com/docker/compose/releases/download/1.23.2/docker-compose-$(uname -s)-$(uname -m)" -o /usr/local/bin/docker-compose
sudo chmod a+x /usr/local/bin/docker-compose

# Add current user to the docker group
sudo usermod -a -G docker $USER
# Enable & start docker service
sudo systemctl enable docker
sudo systemctl start docker

After running this shell script, log out & login from the system in order for the docker group to be added to the current user.

Creating the directory & docker-compose configuration

We will install Gitlab in /var/lib/gitlab which will host the data directories and the docker-compose script. You can use any directory if you use it consistently in all the configs (most importantly, docker-compose.yml and the systemd service).

# Create directories
sudo mkdir /var/lib/gitlab

Next, we’ll create /var/lib/gitlab/docker-compose.yml.

There’s a couple of things you need to change here:

  • Set gitlab_rails['gitlab_email_from'] and gitlab_rails['gitlab_email_display_name'] to whatever sender address & name you want emails to be sent from
  • Set the SMTP credentials (gitlab_rails['smtp_address'], gitlab_rails['smtp_port'], gitlab_rails['smtp_user_name'], gitlab_rails['smtp_password'] & gitlab_rails['smtp_domain']) to a valid SMTP server. In rare cases you also have to change the other gitlab_rails['smtp_...'] settings.
  • You need to change every 4 occurrences of gitlab.mydomain.de to your domain.
  • The ports configuration, in this case '9080:80' means that Gitlab will be mapped to port 9080 on the local PC. This port is chosen somewhat arbitarily – as we will run Gitlab behind an nginx reverse proxy, the port does not need to be any port in particular (as long as you use the same port everywhere), but it may not be used by anything else. You can use any port here, provided that it’s not used for anything else. Leave 80 as-is and only change 9080 if required.
gitlab:
   image: 'gitlab/gitlab-ce:latest'
   restart: always
   hostname: 'gitlab.mydomain.de'
   environment:
     GITLAB_OMNIBUS_CONFIG: |
       external_url 'https://gitlab.mydomain.de'
       letsencrypt['enabled'] = false
       # Email
       gitlab_rails['gitlab_email_enabled'] = true
       gitlab_rails['gitlab_email_from'] = 'gitlab@mydomain.de'
       gitlab_rails['gitlab_email_display_name'] = 'My GitLab'
       # SMTP
       gitlab_rails['smtp_enable'] = true
       gitlab_rails['smtp_address'] = "mail.mydomain.de"
       gitlab_rails['smtp_port'] = 25
       gitlab_rails['smtp_user_name'] = "gitlab@mydomain.de"
       gitlab_rails['smtp_password'] = "yourSMTPPassword"
       gitlab_rails['smtp_domain'] = "mydomain.de"
       gitlab_rails['smtp_authentication'] = "login"
       gitlab_rails['smtp_enable_starttls_auto'] = true
       gitlab_rails['smtp_tls'] = true
       gitlab_rails['smtp_openssl_verify_mode'] = 'none'
       # Reverse proxy nginx config
       nginx['listen_port'] = 80
       nginx['listen_https'] = false
       nginx['proxy_set_headers'] = {
         "X-Forwarded-Proto" => "https",
         "X-Forwarded-Ssl" => "on",
         "Host" => "gitlab.mydomain.de",
         "X-Real-IP" => "$$remote_addr",
         "X-Forwarded-For" => "$$proxy_add_x_forwarded_for",
         "Upgrade" => "$$http_upgrade",
         "Connection" => "$$connection_upgrade"
       }
   ports:
     - '9080:80'
   volumes:
     - '/var/lib/gitlab/config:/etc/gitlab'
     - '/var/lib/gitlab/logs:/var/log/gitlab'
     - '/var/lib/gitlab/data:/var/opt/gitlab'

Setting up the systemd service

Next, we’ll configure the systemd service in /etc/systemd/system/gitlab.service.

Set User=... to your current user in the [Service] section.

[Unit]
Description=Gitlab
Requires=docker.service
After=docker.service

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

[Install]
WantedBy=multi-user.target

After creating the file, we can enable and start the redmine service:

sudo systemctl enable gitlab
sudo systemctl start gitlab

The output of sudo systemctl start gitlab should be empty. In case it is

Job for gitlab.service failed because the control process exited with error code.
See "systemctl status gitlab.service" and "journalctl -xe" for details.

you can debug the issue using journalctl -xe and journalctl -e

The first startup usually takes about 10 minutes, so grab at least one cup of coffee. You can follow the progress using journalctl -xefu gitlab. Once you see lines like

Dec 17 17:28:04 instance-1 docker-compose[4087]: gitlab_1  | {"method":"GET","path":"/-/metrics","format":"html","controller":"MetricsController","action":"index","status":200,"duration":28.82,"view":22.82,"db":0.97,"time":"2018-12-17T17:28:03.252Z","params":[],"remote_ip":null,"user_id":null,"username":null,"ua":null}

the startup is finished.

Now you can check if GitLab is running using

wget -O- http://localhost:9080/

(if you changed the port config before, you need to use your custom port in the URL).

If it worked, it will show a debug message output. Since gitlab will automatically redirect you to your domain (gitlab.mydomain.de in this example) you should see something like

--2018-12-17 17:28:32--  http://localhost:9080/
Resolving localhost (localhost)... 127.0.0.1
Connecting to localhost (localhost)|127.0.0.1|:9080... connected.
HTTP request sent, awaiting response... 302 Found
Location: https://gitlab.gridbox.de/users/sign_in [following]
--2018-12-17 17:28:32--  https://gitlab.mydomain.de/users/sign_in
Resolving gitlab.gridbox.de (gitlab.mydomain.de)... 35.198.165.121
Connecting to gitlab.gridbox.de (gitlab.mydomain.de)|35.198.165.121|:443... failed: Connection refused.

Since we have not setup nginx as a reverse proxy yet, it’s totally fine that it’s saying connection refused. The redirection worked if you see the output listed above.

Setting up the nginx reverse proxy (optional but recommended)

We’ll use nginx to proxy the requests from a certain domain (Using Apache, if you use it already, is also possible but it is outside the scope of this tutorial to tell you how to do that). Install it using

sudo apt -y install nginx

First, you’ll need a domain name with DNS being configured. For this example, we’ll assume that your domain name is gitlab.mydomain.de ! You need to change it to your domain name!

First, we’ll create the config file in /etc/nginx/sites-enabled/gitlab.conf. Remember to replace gitlab.mydomain.de by your domain name! If you use a port different from 9080, replace that as ewll.

map $http_upgrade $connection_upgrade {
    default upgrade;
    '' close;
}

server {
    server_name gitlab.mydomain.de;

    access_log /var/log/nginx/gitlab.access_log;
    error_log /var/log/nginx/gitlab.error_log info;

    location / {
        proxy_pass http://127.0.0.1:9080; # docker container listens here
        proxy_read_timeout 3600s;
        proxy_http_version 1.1;
        # Websocket connection
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection $connection_upgrade;
    }

    listen 80;
}

Now run sudo nginx -t to test if there are any errors in the config file. If everything is alright, you’ll see

nginx: the configuration file /etc/nginx/nginx.conf syntax is ok
nginx: configuration file /etc/nginx/nginx.conf test is successful

Once you have fixed all errors, if any, run sudo service nginx reload to apply the configuration.

We need to setup a Let’s Encrypt SSL certificate before we can check if Gitlab is working:

Securing the nginx reverse proxy using Let’s Encrypt

First we need to install certbot and the certbot nginx plugin in order to create & install the certificate in nginx:

sudo apt -y install python3-certbot python3-certbot-nginx

Fortunately certbot automates most of the process of installing & configuring SSL and the certificate. Run

sudo certbot --nginx

It will ask you to enter your Email address and agree to the terms of service and if you want to receive the EFF newsletter.

After that, certbot will ask you to select the correct domain name:

Which names would you like to activate HTTPS for?
-------------------------------------------------------------------------------
1: gitlab.mydomain.de
-------------------------------------------------------------------------------
Select the appropriate numbers separated by commas and/or spaces, or leave input
blank to select all options shown (Enter 'c' to cancel):

In this case, there is only one domain name (there will be more if you have more domains active on nginx!).

Therefore, enter 1 and press enter. certbot will now generate the certificate. In case of success you will see an output including a line like

Deploying Certificate to VirtualHost /etc/nginx/sites-enabled/gitlab.mydomain.de.conf

Now it will ask you whether to redirect all requests to HTTPS automatically:

Please choose whether or not to redirect HTTP traffic to HTTPS, removing HTTP access.
-------------------------------------------------------------------------------
1: No redirect - Make no further changes to the webserver configuration.
2: Redirect - Make all requests redirect to secure HTTPS access. Choose this for
new sites, or if you're confident your site works on HTTPS. You can undo this
change by editing your web server's configuration.
-------------------------------------------------------------------------------
Select the appropriate number [1-2] then [enter] (press 'c' to cancel): 

Choose Redirect here: Type 2 and press enter. Now you can login to GitLab and finish the installation.

You need to renew the certificate every 3 months for it to stay valid, and run sudo service nginx reload afterwards to use the new certificate. If you fail to do this, users will see certificate expired error messages and won’t be able to access Redmine easily! See this post for details on how to mostly automate this process!

Setting up Redmine

Now you can open a browser and have a first look at your new GitLab installation:

Set the new password and then login with the username root and your newly set password.

After that, open the admin area at the top by clicking at the wrench icon in the purple navigation bar at the top.

At the navigation bar at the left, click on Settings (it’s at the bottom – you need to scroll down) and then click on General.

Click the Expand button to the right of Visibility and access controls. Scroll down until you see Enabled Git access protocols and select Only HTTP(S) in the combo box.

Then click the green Save changes button.

Since we have now disabled SSH access (which we didn’t set up in the first place), you can now use GitLab. A good place to start is to create a new project and try checking it out. See this article on how to store git https passwords so you don’t have to enter your git password every time.

Note: If GitLab doesn’t send emails, check config/gitlab.rb, search for smtp and if neccessary fix the SMTP settings there. After that, sudo systemctl stop gitlab && sudo systemctl start gitlab

Posted by Uli Köhler in Container, Docker, git, nginx, Version management

How to store git HTTPS passwords / credentials permanently so you only have to enter them once

Problem:

Every time you clone a git repository or push/pull, you have to enter a username and a password (e.g. for GitHub or your GitLab installation).
Instead, you want git to store the password so you only have to enter it once.

Solution:

Configure the git credential helper to use a plaintext store instead of the default cache:

git config --global credential.helper store

NOTE: This approach will store your passwords in a plaintext file, so depending on your setup this might be a security risk.

Posted by Uli Köhler in git, Version management

How to solve git: fatal: No configured push destination

Problem:

You  have initialized a git repository in a folder using

git init

Now that you have made some commits, you want to use

git push

but you get the following error message:

fatal: No configured push destination.
Either specify the URL from the command-line or configure a remote repository using

    git remote add <name> <url>

and then push using the remote name

    git push <name>

Solution:

As you initialized your repository using git init, git does not know which server to contact when you use git push.

Therefore, we’ll have to add a server (called remote in git terminology) to the repository:

git remote add origin git@github.com:yourusername/yourrepository.git

Remember to replace git@github.com:yourusername/yourrepository.git with the correct URL for your repository. Valid example URLs include:

  • https://github.com/ulikoehler/UliEngineering.git
  • git@github.com:ulikoehler/UliEngineering.git

This adds a server (remote add) named origin with the URL git@github.com:yourusername/yourrepository.git.

The URL (last argument) depends on the server you use, for GitHub, you can get the URL (HTTPS or SSH, both will work) by clicking the green Clone or Download button.

Now you can push your existing data to the server. git push by itself won’t work for the first time, because git doesn’t know automatically that you want to push to origin. Therefore we have to tell it using --set-upstream that future git push commands shall automatically push to origin:

git push --set-upstream origin master

If this command lists an error, you likely used the wrong URL for the repository or you don’t use the correct credentials (username/password, SSH key etc).

From now on, you can just use

git push

every time you’ve made a commit in order to push it to the server.

Note: origin is no special name, it’s just the name git uses for the server when you git clone a repository. Therefore it’s the standard name for your main server to push to. Similarly, git uses master as the default branch name.

Posted by Uli Köhler in git, Version management

git svn: Clone latest revision only

Problem:

You want to use git-svn to clone a SVN repository, but you don’t want to clone the entire history (which can be quite slow) but only the latest revision.

Continue reading →

Posted by Uli Köhler in git, Shell, Subversion, Version management