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Connecting to Host Services

Dagger Functions do not have access to the network of the host you invoke the Dagger Function from (i.e. the host you execute a CLI command like dagger call from). Instead, host network services need to be explicitly passed when executing dagger call.

TCP and UDP Services​

To pass host TCP or UDP network services as arguments when invoking a Dagger Function, specify them in the form tcp://<host>:<port> or udp://<host>:<port>.

Assume that you have a PostgresQL database running locally on port 5432, as with:

docker run -d -e POSTGRES_PASSWORD=postgres -p 5432:5432 postgres

Here is an example of passing this host service as argument to a PostgreSQL client Dagger Function, which drops you to a prompt from where you can execute SQL queries:

dagger -m github.com/kpenfound/dagger-modules/postgres@v0.1.0 call client --db=postgres --user=postgres --password=postgres --server=tcp://localhost:5432

Unix Sockets​

Similar to host TCP/UDP services, Dagger Functions can also be granted access to host Unix sockets when the client is running on Linux or MacOS.

To pass host Unix sockets as arguments when invoking a Dagger Function, specify them by their path on the host.

For example, assuming you have Docker on your host with the Docker daemon listening on a Unix socket at /var/run/docker.sock, you can pass this socket to a Docker client Dagger Function as follows:

dagger -m github.com/sipsma/daggerverse/docker-client@v0.0.1 call --sock=/var/run/docker.sock version