Clone the repository, then from the root of the repository run to build with default sqlite backend:

Recommended way to build

Please read the documentation provided in the docker directory for the latest information on how to build Vaultwarden locally.
This can be done via docker or podman. See: https://github.com/dani-garcia/vaultwarden/tree/main/docker

Simple ways to build

# Build the docker image with all databases supported:
docker buildx build -t vaultwarden .

To build with SQLite backend only run:

# Build the docker image:
docker buildx build -t vaultwarden --build-arg DB=sqlite .

To build with MySQL backend only run:

# Build the docker image:
docker buildx build -t vaultwarden --build-arg DB=mysql .

To build with Postgresql backend only run:

# Build the docker image:
docker buildx build -t vaultwarden --build-arg DB=postgresql .

in docker-compose.yml it looks like

  vaultwarden:
    image: vaultwarden
    build:
      context: vaultwarden
      args:
        DB: postgresql