Origins of this project: some best practices

Minimize the payload in the server side session and use a non in-memory session storage backend to provide non-disruptive deployments

For a single server scenario this can be achieved with combining it with Tomcat's parallel deployment feature. [Example]

In a multi server + load balancer set up, this also provides fully transparant fail-over in case of any failure on the hosts.

Put your (web-)application config files into /etc, make it reloadable, make it possible to overwrite entries via System.setProperty to support config changes in unit-tests. AbstractProperties implements everything you need.
Put your logging config (like logback.xml) into /etc. Consider making it reloadable and write log files to /var/log. BaseConfigurator makes this very simple.
Put the git commit hash, build time and build tag during build time into your artifacts and show it somewhere. See VersionFromManifest how this library can help.
Start right away with secure connections. Use letsencrypt, set up your database connections securely. A script to use letsencrypt with Tomcat.
Consider jmxtrans to monitor your Tomcat instance. A template config file, using is just adding this to your tomcat start script: JAVA_OPTS="${JAVA_OPTS} -javaagent:/var/lib/tomcat7/jmxtrans/jmxtrans-agent.jar=/var/lib/tomcat7/jmxtrans/jmxtrans.xml" and putting adding the jar.

Project: de.oglimmer.utils

Description

The library helps to prevent boilerplate code for random strings and names, SPI-based slf4j configuration, sophisticated property files, human readable representation of date differences and getting attributes from MANIFEST.FM files.

Source / JavaDoc / Binaries

The sources can be found at github. The javadoc can be found at here. Download/use the latest binaries from maven central.

Detailed information with examples

Class: de.oglimmer.utils.VersionFromManifest

Helps to read attributes from a Manifest file and provides a uniform "version" string which has version, git-commit, creation date and a html-link to git

An example project is on github.

1.) add this to your pom.xml, to add the information into the MANIFEST.FM file: 2.) add this to your pom.xml to retrieve the git commit hash: 3.) use a ServletContextListener.contextInitialized(ServletContextEvent) to get a proper version string

Class: de.oglimmer.utils.BaseConfigurator

Implements SPI-based slf4j configuration. It changes the order and places where slf4j looks for configuration files. The "APP_NAME" is given as a parameter in the constructor. Checks first the system parameter "APP_NAME"-logback for a filename, if this parameter is not given or the file doesn't exist it looks in /etc/logback-custom.xml. If all this doesn't exist it uses /logback-custom.xml in the $CLASSPATH. It also sets the slf4j variable "application-name" with the "APP_NAME".

Create a class in your project and extend it from de.oglimmer.utils.BaseConfigurator
Have a parameter less constructor and set your application name in super("....");
Create META-INF/services/ch.qos.logback.classic.spi.Configurator under src/main/resources
Put the full qualified filename of your class from (1) into that file
make sure you have a logback-custom.xml in your project (and not logback.xml)

Class: de.oglimmer.utils.AbstractProperties

A base class for application property classes. Supports json-based config files, automatic reloads when the file changes, merging in-classpath and out-of-classpath files and can take the whole configuration from a string to support unit test configurations.

Create a (singleton) class in your project and extends it from de.oglimmer.utils.AbstractProperties
Have a parameter less constructor and pass the name of the system parameter to your production config file to super("...."), e.g. super("my_app")
create as many getters as you need like

put a default.properties into src/main/resources. this needs to be a json file and should hold all default/development values for all properties
On your production host start the server with -Dmy_app=/etc/my_app.properties