The concat package implements a charm that takes all the string values from units on upstream relations, concatenates them and makes them available to downstream relations.

Package do-nothing implements the simplest possible Go charm.

The helloworld package implements an example charm that exposes an HTTP service that returns "hello, world" from every endpoint.

The helloworld-configurable package implements an example charm similar to http://godoc.org/github.com/juju/gocharm/example-charms/helloworld but which allows the message to be configured, demonstrating how changing configuration options can affect a running service.

The mongodbclient package implements an example charm that acts as the client of the mongodb charm.