Application properties

(3Q20)

This article provides information on working with property files for exist applications.

Introduction

For most applications it is a good idea to provide settings in a property file. An exist-db-addons library, available in maven central, enables you to do so.

usage

Below a setup for exist-db for properties.

Include exist-db-addons

For example in a Dockerfile:

ARG EXISTADDONSERSION=2.3
COPY exist-db-addons-${EXISTADDONSERSION}.jar $EXIST_HOME/lib/
ENV CLASSPATH=$EXIST_HOME/lib/exist.uber.jar:$EXIST_HOME/lib/exist-db-addons-${EXISTADDONSERSION}.jar

Or include a dependency in exist-db's pom.xml:

<dependency>
  <groupId>
    org.fryske-akademy
  </groupId>
  <artifactId>
    exist-db-addons
  </artifactId>
  <version>
    2.3
  </version>
</dependency>

configure in conf.xml

add the module to exist:

<module uri="http://exist-db.org/xquery/properties" class="org.fryske_akademy.exist.properties.PropertiesModule">
  <parameter name="basePath" value="/run/secrets"/>
</module>

use properties in xquery

load and use properties in your xquery

declare namespace properties="http://exist-db.org/xquery/properties";

declare variable $teidictjson:props := properties:loadProperties("teidictjson.properties");

declare function teidictjson:getProperty($key as xs:string, $default as xs:string) as xs:string {
    if (map:contains($teidictjson:props,$key)) then
        map:get($teidictjson:props,$key)
    else
        $default
};

optionally mount properties as docker secret

In docker-compose.yml:

secrets:
  - source: ${APPNAME}.properties
    target: teidictjson.properties
    mode: 0444
secrets:
  fhwbjson.properties:
    external: true