Installation with Docker

Gitea provides automatically updated Docker images within its Docker Hub organization. It is possible to always use the latest stable tag or to use another service that handles updating Docker images.

This reference setup guides users through the setup based on docker-compose, but the installation of docker-compose is out of scope of this documentation. To install docker-compose itself, follow the official install instructions.

Basics

The most simple setup just creates a volume and a network and starts the gitea/gitea:latest image as a service. Since there is no database available, one can be initialized using SQLite3. Create a directory like gitea and paste the following content into a file named docker-compose.yml. Note that the volume should be owned by the user/group with the UID/GID specified in the config file. If you don’t give the volume correct permissions, the container may not start. For a stable release you can use :latest, :1 or specify a certain release like :1.19.4, but if you’d like to use the latest development version of Gitea then you could use the :nightly tag. If you’d like to run the latest commit from a release branch you can use the :1.x-nightly tag, where x is the minor version of Gitea. (e.g. :1.16-nightly)

  1. version: "3"
  3. networks:
  4.   gitea:
  5.     external: false
  7. services:
  8.   server:
  9.     image: gitea/gitea:1.19.4
  10.     container_name: gitea
  11.     environment:
  12.       - USER_UID=1000
  13.       - USER_GID=1000
  14.     restart: always
  15.     networks:
  16.       - gitea
  17.     volumes:
  18.       - ./gitea:/data
  19.       - /etc/timezone:/etc/timezone:ro
  20.       - /etc/localtime:/etc/localtime:ro
  21.     ports:
  22.       - "3000:3000"
  23.       - "222:22"

Ports

To bind the integrated OpenSSH daemon and the webserver on a different port, adjust the port section. It’s common to just change the host port and keep the ports within the container like they are.

  1. version: "3"
  3. networks:
  4.   gitea:
  5.     external: false
  7. services:
  8.   server:
  9.     image: gitea/gitea:1.19.4
  10.     container_name: gitea
  11.     environment:
  12.       - USER_UID=1000
  13.       - USER_GID=1000
  14.     restart: always
  15.     networks:
  16.       - gitea
  17.     volumes:
  18.       - ./gitea:/data
  19.       - /etc/timezone:/etc/timezone:ro
  20.       - /etc/localtime:/etc/localtime:ro
  21.     ports:
  22. -     - "3000:3000"
  23. -     - "222:22"
  24. +     - "8080:3000"
  25. +     - "2221:22"

Databases

MySQL database

To start Gitea in combination with a MySQL database, apply these changes to the docker-compose.yml file created above.

  1. version: "3"
  3. networks:
  4.   gitea:
  5.     external: false
  7. services:
  8.   server:
  9.     image: gitea/gitea:1.19.4
  10.     container_name: gitea
  11.     environment:
  12.       - USER_UID=1000
  13.       - USER_GID=1000
  14. +      - GITEA__database__DB_TYPE=mysql
  15. +      - GITEA__database__HOST=db:3306
  16. +      - GITEA__database__NAME=gitea
  17. +      - GITEA__database__USER=gitea
  18. +      - GITEA__database__PASSWD=gitea
  19.     restart: always
  20.     networks:
  21.       - gitea
  22.     volumes:
  23.       - ./gitea:/data
  24.       - /etc/timezone:/etc/timezone:ro
  25.       - /etc/localtime:/etc/localtime:ro
  26.     ports:
  27.       - "3000:3000"
  28.       - "222:22"
  29. +    depends_on:
  30. +      - db
  31. +
  32. +  db:
  33. +    image: mysql:8
  34. +    restart: always
  35. +    environment:
  36. +      - MYSQL_ROOT_PASSWORD=gitea
  37. +      - MYSQL_USER=gitea
  38. +      - MYSQL_PASSWORD=gitea
  39. +      - MYSQL_DATABASE=gitea
  40. +    networks:
  41. +      - gitea
  42. +    volumes:
  43. +      - ./mysql:/var/lib/mysql

PostgreSQL database

To start Gitea in combination with a PostgreSQL database, apply these changes to the docker-compose.yml file created above.

  1. version: "3"
  3. networks:
  4.   gitea:
  5.     external: false
  7. services:
  8.   server:
  9.     image: gitea/gitea:1.19.4
  10.     container_name: gitea
  11.     environment:
  12.       - USER_UID=1000
  13.       - USER_GID=1000
  14. +      - GITEA__database__DB_TYPE=postgres
  15. +      - GITEA__database__HOST=db:5432
  16. +      - GITEA__database__NAME=gitea
  17. +      - GITEA__database__USER=gitea
  18. +      - GITEA__database__PASSWD=gitea
  19.     restart: always
  20.     networks:
  21.       - gitea
  22.     volumes:
  23.       - ./gitea:/data
  24.       - /etc/timezone:/etc/timezone:ro
  25.       - /etc/localtime:/etc/localtime:ro
  26.     ports:
  27.       - "3000:3000"
  28.       - "222:22"
  29. +    depends_on:
  30. +      - db
  31. +
  32. +  db:
  33. +    image: postgres:14
  34. +    restart: always
  35. +    environment:
  36. +      - POSTGRES_USER=gitea
  37. +      - POSTGRES_PASSWORD=gitea
  38. +      - POSTGRES_DB=gitea
  39. +    networks:
  40. +      - gitea
  41. +    volumes:
  42. +      - ./postgres:/var/lib/postgresql/data

Named volumes

To use named volumes instead of host volumes, define and use the named volume within the docker-compose.yml configuration. This change will automatically create the required volume. You don’t need to worry about permissions with named volumes; Docker will deal with that automatically.

  1. version: "3"
  3. networks:
  4.   gitea:
  5.     external: false
  7. +volumes:
  8. +  gitea:
  9. +    driver: local
  10. +
  11. services:
  12.   server:
  13.     image: gitea/gitea:1.19.4
  14.     container_name: gitea
  15.     restart: always
  16.     networks:
  17.       - gitea
  18.     volumes:
  19. -      - ./gitea:/data
  20. +      - gitea:/data
  21.       - /etc/timezone:/etc/timezone:ro
  22.       - /etc/localtime:/etc/localtime:ro
  23.     ports:
  24.       - "3000:3000"
  25.       - "222:22"

MySQL or PostgreSQL containers will need to be created separately.

Startup

To start this setup based on docker-compose, execute docker-compose up -d, to launch Gitea in the background. Using docker-compose ps will show if Gitea started properly. Logs can be viewed with docker-compose logs.

To shut down the setup, execute docker-compose down. This will stop and kill the containers. The volumes will still exist.

Notice: if using a non-3000 port on http, change app.ini to match LOCAL_ROOT_URL = http://localhost:3000/.

Installation

After starting the Docker setup via docker-compose, Gitea should be available using a favorite browser to finalize the installation. Visit http://server-ip:3000 and follow the installation wizard. If the database was started with the docker-compose setup as documented above, please note that db must be used as the database hostname.

Configure the user inside Gitea using environment variables

  • USER: git: The username of the user that runs Gitea within the container.
  • USER_UID: 1000: The UID (Unix user ID) of the user that runs Gitea within the container. Match this to the UID of the owner of the /data volume if using host volumes (this is not necessary with named volumes).
  • USER_GID: 1000: The GID (Unix group ID) of the user that runs Gitea within the container. Match this to the GID of the owner of the /data volume if using host volumes (this is not necessary with named volumes).

Customization

Customization files described here should be placed in /data/gitea directory. If using host volumes, it’s quite easy to access these files; for named volumes, this is done through another container or by direct access at /var/lib/docker/volumes/gitea_gitea/_data. The configuration file will be saved at /data/gitea/conf/app.ini after the installation.

Upgrading

❗❗ Make sure you have volumed data to somewhere outside Docker container ❗❗

To upgrade your installation to the latest release:

  1. # Edit `docker-compose.yml` to update the version, if you have one specified
  2. # Pull new images
  3. docker-compose pull
  4. # Start a new container, automatically removes old one
  5. docker-compose up -d

Managing Deployments With Environment Variables

In addition to the environment variables above, any settings in app.ini can be set or overridden with an environment variable of the form: GITEA__SECTION_NAME__KEY_NAME. These settings are applied each time the docker container starts. Full information here.

These environment variables can be passed to the docker container in docker-compose.yml. The following example will enable an smtp mail server if the required env variables GITEA__mailer__FROM, GITEA__mailer__HOST, GITEA__mailer__PASSWD are set on the host or in a .env file in the same directory as docker-compose.yml:

  1. ...
  2. services:
  3.   server:
  4.     environment:
  5.       - GITEA__mailer__ENABLED=true
  6.       - GITEA__mailer__FROM=${GITEA__mailer__FROM:?GITEA__mailer__FROM not set}
  7.       - GITEA__mailer__MAILER_TYPE=smtp
  8.       - GITEA__mailer__HOST=${GITEA__mailer__HOST:?GITEA__mailer__HOST not set}
  9.       - GITEA__mailer__IS_TLS_ENABLED=true
  10.       - GITEA__mailer__USER=${GITEA__mailer__USER:-apikey}
  11.       - GITEA__mailer__PASSWD="""${GITEA__mailer__PASSWD:?GITEA__mailer__PASSWD not set}"""

Gitea will generate new secrets/tokens for every new installation automatically and write them into the app.ini. If you want to set the secrets/tokens manually, you can use the following docker commands to use of Gitea’s built-in generate utility functions. Do not lose/change your SECRET_KEY after the installation, otherwise the encrypted data can not be decrypted anymore.

The following commands will output a new SECRET_KEY and INTERNAL_TOKEN to stdout, which you can then place in your environment variables.

  1. docker run -it --rm gitea/gitea:1 gitea generate secret SECRET_KEY
  2. docker run -it --rm  gitea/gitea:1 gitea generate secret INTERNAL_TOKEN
  1. ...
  2. services:
  3.   server:
  4.     environment:
  5.       - GITEA__security__SECRET_KEY=[value returned by generate secret SECRET_KEY]
  6.       - GITEA__security__INTERNAL_TOKEN=[value returned by generate secret INTERNAL_TOKEN]

SSH Container Passthrough

Since SSH is running inside the container, SSH needs to be passed through from the host to the container if SSH support is desired. One option would be to run the container SSH on a non-standard port (or moving the host port to a non-standard port). Another option which might be more straightforward is for Gitea users to ssh to a Gitea user on the host which will then relay those connections to the docker.

Understanding SSH access to Gitea (without passthrough)

To understand what needs to happen, you first need to understand what happens without passthrough. So we will try to explain this:

  1. The client adds their SSH public key to Gitea using the webpage.
  2. Gitea will add an entry for this key to the .ssh/authorized_keys file of its running user, git.
  3. This entry has the public key, but also has a command= option. It is this command that Gitea uses to match this key to the client user and manages authentication.
  4. The client then makes an SSH request to the SSH server using the git user, e.g. git clone git@domain:user/repo.git.
  5. The client will attempt to authenticate with the server, passing one or more public keys one at a time to the server.
  6. For each key the client provides, the SSH server will first check its configuration for an AuthorizedKeysCommand to see if the public key matches, and then the git user’s authorized_keys file.
  7. The first entry that matches will be selected, and assuming this is a Gitea entry, the command= will now be executed.
  8. The SSH server creates a user session for the git user, and using the shell for the git user runs the command=
  9. This runs gitea serv which takes over control of the rest of the SSH session and manages gitea authentication & authorization of the git commands.

Now, for the SSH passthrough to work, we need the host SSH to match the public keys and then run the gitea serv on the docker. There are multiple ways of doing this. However, all of these require some information about the docker being passed to the host.

SSHing Shim (with authorized_keys)

In this option, the idea is that the host simply uses the authorized_keys that gitea creates but at step 9 the gitea command that the host runs is a shim that actually runs ssh to go into the docker and then run the real docker gitea itself.

  • To make the forwarding work, the SSH port of the container (22) needs to be mapped to the host port 2222 in docker-compose.yml . Since this port does not need to be exposed to the outside world, it can be mapped to the localhost of the host machine:

    1. ports:
    2.   # [...]
    3.   - "127.0.0.1:2222:22"

  • Next on the host create the git user which shares the same UID/ GID as the container values USER_UID/ USER_GID. These values can be set as environment variables in the docker-compose.yml:

    1. environment:
    2.   - USER_UID=1000
    3.   - USER_GID=1000

  • Mount /home/git/.ssh of the host into the container. This ensures that the authorized_keys file is shared between the host git user and the container git user otherwise the SSH authentication cannot work inside the container.

    1. volumes:
    2.   - /home/git/.ssh/:/data/git/.ssh

  • Now a SSH key pair needs to be created on the host. This key pair will be used to authenticate the git user on the host to the container. As an administrative user on the host run: (by administrative user we mean a user that can sudo to root)

    1. sudo -u git ssh-keygen -t rsa -b 4096 -C "Gitea Host Key"

  • Please note depending on the local version of ssh you may want to consider using -t ecdsa here.

  • /home/git/.ssh/authorized_keys on the host now needs to be modified. It needs to act in the same way as authorized_keys within the Gitea container. Therefore add the public key of the key you created above (“Gitea Host Key”) to ~/git/.ssh/authorized_keys. As an administrative user on the host run:

    1. sudo -u git cat /home/git/.ssh/id_rsa.pub | sudo -u git tee -a /home/git/.ssh/authorized_keys
    2. sudo -u git chmod 600 /home/git/.ssh/authorized_keys

    Important: The pubkey from the git user needs to be added “as is” while all other pubkeys added via the Gitea web interface will be prefixed with command="/usr [...].

    /home/git/.ssh/authorized_keys should then look somewhat like

    1. # SSH pubkey from git user
    2. ssh-rsa <Gitea Host Key>
    4. # other keys from users
    5. command="/usr/local/bin/gitea --config=/data/gitea/conf/app.ini serv key-1",no-port-forwarding,no-X11-forwarding,no-agent-forwarding,no-pty <user pubkey>

  • The next step is to create the fake host gitea command that will forward commands from the host to the container. The name of this file depends on your version of Gitea:

    • For Gitea v1.16.0+. As an administrative user on the host run:

      1. cat <<"EOF" | sudo tee /usr/local/bin/gitea
      2. #!/bin/sh
      3. ssh -p 2222 -o StrictHostKeyChecking=no git@127.0.0.1 "SSH_ORIGINAL_COMMAND=\"$SSH_ORIGINAL_COMMAND\" $0 $@"
      4. EOF
      5. sudo chmod +x /usr/local/bin/gitea

Here is a detailed explanation what is happening when a SSH request is made:

  1. The client adds their SSH public key to Gitea using the webpage.
  2. Gitea in the container will add an entry for this key to the .ssh/authorized_keys file of its running user, git.
    • However, because /home/git/.ssh/ on the host is mounted as /data/git/.ssh this means that the key has been added to the host git user’s authorized_keys file too.
  3. This entry has the public key, but also has a command= option.
    • This command matches the location of the Gitea binary on the container, but also the location of the shim on the host.
  4. The client then makes an SSH request to the host SSH server using the git user, e.g. git clone git@domain:user/repo.git.
  5. The client will attempt to authenticate with the server, passing one or more public keys in turn to the host.
  6. For each key the client provides, the host SSH server will first check its configuration for an AuthorizedKeysCommand to see if the public key matches, and then the host git user’s authorized_keys file.
    • Because /home/git/.ssh/ on the host is mounted as /data/git/.ssh this means that the key they added to the Gitea web will be found
  7. The first entry that matches will be selected, and assuming this is a Gitea entry, the command= will now be executed.
  8. The host SSH server creates a user session for the git user, and using the shell for the host git user runs the command=
  9. This means that the host runs the host /usr/local/bin/gitea shim that opens an SSH from the host to container passing the rest of the command arguments directly to /usr/local/bin/gitea on the container.
  10. Meaning that the container gitea serv is run, taking over control of the rest of the SSH session and managing gitea authentication & authorization of the git commands.

Notes

SSH container passthrough using authorized_keys will work only if

  • opensshd is used in the container
  • if AuthorizedKeysCommand is not used in combination with SSH_CREATE_AUTHORIZED_KEYS_FILE=false to disable authorized files key generation
  • LOCAL_ROOT_URL is not changed (depending on the changes)

If you try to run gitea on the host, you will attempt to ssh to the container and thence run the gitea command there.

Never add the Gitea Host Key as a SSH key to a user on the Gitea interface.

SSHing Shell (with authorized_keys)

In this option, the idea is that the host simply uses the authorized_keys that gitea creates but at step 8 above we change the shell that the host runs to ssh directly into the docker and then run the shell there. This means that the gitea that is then run is the real docker gitea.

  • In this case we setup as per SSHing Shim except instead of creating /usr/local/bin/gitea we create a new shell for the git user. As an administrative user on the host run:

    1. cat <<"EOF" | sudo tee /home/git/ssh-shell
    2. #!/bin/sh
    3. shift
    4. ssh -p 2222 -o StrictHostKeyChecking=no git@127.0.0.1 "SSH_ORIGINAL_COMMAND=\"$SSH_ORIGINAL_COMMAND\" $@"
    5. EOF
    6. sudo chmod +x /home/git/ssh-shell
    7. sudo usermod -s /home/git/ssh-shell git

    Be careful here - if you try to login as the git user in future you will ssh directly to the docker.

Here is a detailed explanation what is happening when a SSH request is made:

  1. The client adds their SSH public key to Gitea using the webpage.
  2. Gitea in the container will add an entry for this key to the .ssh/authorized_keys file of its running user, git.
    • However, because /home/git/.ssh/ on the host is mounted as /data/git/.ssh this means that the key has been added to the host git user’s authorized_keys file too.
  3. This entry has the public key, but also has a command= option.
    • This command matches the location of the Gitea binary on the container.
  4. The client then makes an SSH request to the host SSH server using the git user, e.g. git clone git@domain:user/repo.git.
  5. The client will attempt to authenticate with the server, passing one or more public keys in turn to the host.
  6. For each key the client provides, the host SSH server will first check its configuration for an AuthorizedKeysCommand to see if the public key matches, and then the host git user’s authorized_keys file.
    • Because /home/git/.ssh/ on the host is mounted as /data/git/.ssh this means that the key they added to the Gitea web will be found
  7. The first entry that matches will be selected, and assuming this is a Gitea entry, the command= will now be executed.
  8. The host SSH server creates a user session for the git user, and using the shell for the host git user runs the command=
  9. The shell of the host git user is now our ssh-shell which opens an SSH connection from the host to container, (which opens a shell on the container for the container git).
  10. The container shell now runs the command= option meaning that the container gitea serv is run, taking over control of the rest of the SSH session and managing gitea authentication & authorization of the git commands.

Notes

SSH container passthrough using authorized_keys will work only if

  • opensshd is used in the container
  • if AuthorizedKeysCommand is not used in combination with SSH_CREATE_AUTHORIZED_KEYS_FILE=false to disable authorized files key generation
  • LOCAL_ROOT_URL is not changed (depending on the changes)

If you try to login as the git user on the host in future you will ssh directly to the docker.

Never add the Gitea Host Key as a SSH key to a user on the Gitea interface.

Docker Shell (with authorized_keys)

Similar to the above ssh shell technique we can use a shell which simply uses docker exec. As an administrative user on the host run:

  1. cat <<"EOF" | sudo tee /home/git/docker-shell
  2. #!/bin/sh
  3. /usr/bin/docker exec -i -u git --env SSH_ORIGINAL_COMMAND="$SSH_ORIGINAL_COMMAND" gitea sh "$@"
  4. EOF
  5. sudo chmod +x /home/git/docker-shell
  6. sudo usermod -s /home/git/docker-shell git

Here is a detailed explanation what is happening when a SSH request is made:

  1. The client adds their SSH public key to Gitea using the webpage.
  2. Gitea in the container will add an entry for this key to the .ssh/authorized_keys file of its running user, git.
    • However, because /home/git/.ssh/ on the host is mounted as /data/git/.ssh this means that the key has been added to the host git user’s authorized_keys file too.
  3. This entry has the public key, but also has a command= option.
    • This command matches the location of the Gitea binary on the container.
  4. The client then makes an SSH request to the host SSH server using the git user, e.g. git clone git@domain:user/repo.git.
  5. The client will attempt to authenticate with the server, passing one or more public keys in turn to the host.
  6. For each key the client provides, the host SSH server will first check its configuration for an AuthorizedKeysCommand to see if the public key matches, and then the host git user’s authorized_keys file.
    • Because /home/git/.ssh/ on the host is mounted as /data/git/.ssh this means that the key they added to the Gitea web will be found
  7. The first entry that matches will be selected, and assuming this is a Gitea entry, the command= will now be executed.
  8. The host SSH server creates a user session for the git user, and using the shell for the host git user runs the command=
  9. The shell of the host git user is now our docker-shell which uses docker exec to open a shell for the git user on the container.
  10. The container shell now runs the command= option meaning that the container gitea serv is run, taking over control of the rest of the SSH session and managing gitea authentication & authorization of the git commands.

Note that gitea in the docker command above is the name of the container. If you named yours differently, don’t forget to change that. The host git user also has to have permission to run docker exec.

Notes

Docker shell passthrough using authorized_keys will work only if

  • opensshd is used in the container
  • if AuthorizedKeysCommand is not used in combination with SSH_CREATE_AUTHORIZED_KEYS_FILE=false to disable authorized files key generation
  • LOCAL_ROOT_URL is not changed (depending on the changes)

If you try to login as the git user on the host in future you will docker exec directly to the docker.

A Docker execing shim could be created similarly to above.

Docker Shell with AuthorizedKeysCommand

The AuthorizedKeysCommand route provides another option that does not require many changes to the compose file or the authorized_keys - but does require changes to the host /etc/sshd_config.

In this option, the idea is that the host SSH uses an AuthorizedKeysCommand instead of relying on sharing the authorized_keys file that gitea creates. We continue to use a special shell at step 8 above to exec into the docker and then run the shell there. This means that the gitea that is then run is the real docker gitea.

  • On the host create a git user with permission to run docker exec.

  • We will again assume that the Gitea container is called gitea.

  • Modify the git user’s shell to forward commands to the sh executable inside the container using docker exec. As an administrative user on the host run:

    1. cat <<"EOF" | sudo tee /home/git/docker-shell
    2. #!/bin/sh
    3. /usr/bin/docker exec -i --env SSH_ORIGINAL_COMMAND="$SSH_ORIGINAL_COMMAND" gitea sh "$@"
    4. EOF
    5. sudo chmod +x /home/git/docker-shell
    6. sudo usermod -s /home/git/docker-shell git

Now all attempts to login as the git user on the host will be forwarded to the docker - including the SSH_ORIGINAL_COMMAND. We now need to set-up SSH authentication on the host.

We will do this by leveraging the SSH AuthorizedKeysCommand to match the keys against those accepted by Gitea.

Add the following block to /etc/ssh/sshd_config, on the host:

  1. Match User git
  2.   AuthorizedKeysCommandUser git
  3.   AuthorizedKeysCommand /usr/bin/docker exec -i gitea /usr/local/bin/gitea keys -c /data/gitea/conf/app.ini -e git -u %u -t %t -k %k

(From 1.16.0 you will not need to set the -c /data/gitea/conf/app.ini option.)

Finally restart the SSH server. As an administrative user on the host run:

  1. sudo systemctl restart sshd

Here is a detailed explanation what is happening when a SSH request is made:

  1. The client adds their SSH public key to Gitea using the webpage.
  2. Gitea in the container will add an entry for this key to its database.
  3. The client then makes an SSH request to the host SSH server using the git user, e.g. git clone git@domain:user/repo.git.
  4. The client will attempt to authenticate with the server, passing one or more public keys in turn to the host.
  5. For each key the client provides, the host SSH server will checks its configuration for an AuthorizedKeysCommand.
  6. The host runs the above AuthorizedKeysCommand, which execs in to the docker and then runs the gitea keys command.
  7. Gitea on the docker will look in it’s database to see if the public key matches and will return an entry like that of an authorized_keys command.
  8. This entry has the public key, but also has a command= option which matches the location of the Gitea binary on the container.
  9. The host SSH server creates a user session for the git user, and using the shell for the host git user runs the command=.
  10. The shell of the host git user is now our docker-shell which uses docker exec to open a shell for the git user on the container.
  11. The container shell now runs the command= option meaning that the container gitea serv is run, taking over control of the rest of the SSH session and managing gitea authentication & authorization of the git commands.

Notes

Docker shell passthrough using AuthorizedKeysCommand will work only if

  • The host git user is allowed to run the docker exec command.

If you try to login as the git user on the host in future you will docker exec directly to the docker.

A Docker execing shim could be created similarly to above.

SSH Shell with AuthorizedKeysCommand

Create a key for the host git user as above, add it to the docker /data/git/.ssh/authorized_keys then finally create and set the ssh-shell as above.

Add the following block to /etc/ssh/sshd_config, on the host:

  1. Match User git
  2.   AuthorizedKeysCommandUser git
  3.   AuthorizedKeysCommand /usr/bin/ssh -p 2222 -o StrictHostKeyChecking=no git@127.0.0.1 /usr/local/bin/gitea keys -c /data/gitea/conf/app.ini -e git -u %u -t %t -k %k

(From 1.16.0 you will not need to set the -c /data/gitea/conf/app.ini option.)

Finally restart the SSH server. As an administrative user on the host run:

  1. sudo systemctl restart sshd

Here is a detailed explanation what is happening when a SSH request is made:

  1. The client adds their SSH public key to Gitea using the webpage.
  2. Gitea in the container will add an entry for this key to its database.
  3. The client then makes an SSH request to the host SSH server using the git user, e.g. git clone git@domain:user/repo.git.
  4. The client will attempt to authenticate with the server, passing one or more public keys in turn to the host.
  5. For each key the client provides, the host SSH server will checks its configuration for an AuthorizedKeysCommand.
  6. The host runs the above AuthorizedKeysCommand, which will SSH in to the docker and then run the gitea keys command.
  7. Gitea on the docker will look in it’s database to see if the public key matches and will return an entry like that of an authorized_keys command.
  8. This entry has the public key, but also has a command= option which matches the location of the Gitea binary on the container.
  9. The host SSH server creates a user session for the git user, and using the shell for the host git user runs the command=.
  10. The shell of the host git user is now our git-shell which uses SSH to open a shell for the git user on the container.
  11. The container shell now runs the command= option meaning that the container gitea serv is run, taking over control of the rest of the SSH session and managing gitea authentication & authorization of the git commands.

Notes

SSH container passthrough using AuthorizedKeysCommand will work only if

  • opensshd is running on the container

If you try to login as the git user on the host in future you will ssh directly to the docker.

Never add the Gitea Host Key as a SSH key to a user on the Gitea interface.

SSHing shims could be created similarly to above.