Since the upstream graylogctl script will prefer finding its java
executable based on JAVA_HOME, we now set this instead of PATH in
order to allow it to find the JRE. By setting it conditionally on it
not already being set, we allow selecting a different JRE at runtime.
We also explicitly use openjdk11, which supports the
UseConcMarkSweepGC option which graylog insists on using.
A centralized list for these renames is not good because:
- It breaks disabledModules for modules that have a rename defined
- Adding/removing renames for a module means having to find them in the
central file
- Merge conflicts due to multiple people editing the central file
Until now the startup failed with an error like this:
```
com.github.joschi.jadconfig.ValidationException: Parent path /var/lib/graylog/server for Node ID file at /var/lib/graylog/server/node-id is not a directory
```
This happens since `graylog.service` ensures that `/var/lib/graylog`
exists, however it doesn't take care of the directory for
`cfg.nodeIdFile`.
Included changes:
* upstream repository has moved, URLs changed accordingly
* journaldriver bumped to new upstream release
The new release includes an important workaround for an issue that
could cause log-forwarding to fail after service restarts due to
invalid journal cursors being persisted.
Adds a module for running the journaldriver log forwarding agent via
systemd.
The agent can be deployed on both GCP instances and machines hosted
elsewhere to forward all logs from journald to Stackdriver Logging.
Consult the module options and upstream documentation for more
information.
Implementation notes:
* The service unit is configured to use systemd's dynamic user feature
which will let systemd set up the state directory and appropriate
user configuration at unit launch time instead of hardcoding it.
* The module depends on `network-online.target` to prevent a situation
where journaldriver is failing and restarting multiple times before
the network is online.
