Make externalFilesDir available as a property

[deje07]

The class AndroidContextUtil.java already contains a way to query the external files directory. This is actually the Context.getExternalFilesDir(null). The importance of this directory is than beginning with Android 7 this is a directory where the application can write without asking for permission, and this directory is also publicly readable, making it ideal for storing non-sensitive logfiles during development.
However there is no way to refer to this directory from the logback.xml file, because it is not registered in the logger context properties.

I suggest a new CoreConstants value like EXT_DATA_DIR which points to this directory, if available.

There are also more directories like the externalCacheDir which is also present in AndroidContextUtil but not registered in the logger context.

[wimdeblauwe]

FYI: If you need a workaround, you can use PropertyDefiner (See https://logback.qos.ch/manual/configuration.html#definingPropsOnTheFly). I used it to to expose BuildConfig variables to the XML configuration.

[voghDev]

Hi @wimdeblauwe , could PropertyDefiner be used to add a build.gradle property to the logback.xml file?
Example:

build.gradle

def MY_CUSTOM_HOST = "http://an.example.url"
def MY_CUSTOM_PORT = 1234

logback.xml

<configuration>
    ...

    <appender name="syslog-tls" class="com.papertrailapp.logback.Syslog4jAppender">
        <layout class="ch.qos.logback.classic.PatternLayout">
            <pattern>...</pattern>
        </layout>

        <syslogConfig class="org.productivity.java.syslog4j.impl.net.tcp.ssl.SSLTCPNetSyslogConfig">
            <host>${MY_CUSTOM_HOST}</host>
            <port>${MY_CUSTOM_PORT}</port>
            <sendLocalName>...</sendLocalName>
            <sendLocalTimestamp>...</sendLocalTimestamp>
            <maxMessageLength>...</maxMessageLength>
        </syslogConfig>
    </appender>
    
    ...
</configuration>

In case it can, could you post any example code, link, or public gist that I can check?
Thanks in advance!