14. Urd Database - The Admin

No setup or admin is required to use the Urd database in single user mode. The ax init command will set up an empty database, and the Urd database server starts automatically when the exax server is started using ax server.

This chapter explains is to set up the Urd database server so that its contents can be shared between different users or agents.

14.1. Setup a shared server

To setup a standalone Urd server, two things are needed

• a directory where the database can be stored, and

• a passwd file (stored in the same directory) containing user-password pairs.

Passwords are used to prevent accidental writing into the wrong urdlists. The default name of the database directory is urd.db/. Here’s how it can be done

mkdir urd.db
<editor> urd.db/passwd  # where <editor> is editor of choice, i.e. emacs

The passwd file contains one user-password pair, separated by a colon, per line, like in this example

Example passwd file.

ab:absecret
cd:cdsecret
sh:shsecret
prod:productionsecret

Note

Anyone can read from the database, but only users present in the passwd file can write to the database.

To launch the Urd server, do

start a standalone Urd server

ax urd-server --listen=localhost:8888 --path=./urd.db

# or "ax urd-server --listen=<[host:]port> --path=<path>" in general.

The server will serve requests from multiple users in the order that they arrive.

14.2. Connecting to a Shared Urd Server

To switch to a shared server, the url to the server needs to be put into the accelerator.conf file.

By default, the local Urd database server is serving on a socket in the project directory, and the default configuration file looks something like this

accelerator.conf: Local Urd server is on this socket

urd: local .socket.dir/urd

To listen to an external shared Urd database server, change this to <hostname>:<port> like this

accelerator.conf: Shared Urd server is on port 12345 on localhost.

urd localhost 12345

As soon as the exax server is restarted, it will start using the external shared server.

Note

Remember to populate the passwd file in the shared Urd database server’s urd.db directory to get write access.

To connect to a shared Urd database using a password, set the $URD_AUTH environvent variable to “user:password” for example like this

URD_AUTH=myusername:mysecret ax run mybuildscript

14.3. Directory Structure of the Urd Database

The Urd database has the following structure

database_root/
              passwd
              user1/
                    list1
                    list2
              user2/
                    list3

Each list-file is a transaction log, where each new transaction is appended to the end of the file. It is written in plain text and intended to be (more or less) human readable.