gswrapper

The game server wrapper, also known as gswrapper or gsw, can be used to run a game server executable from within the container image that runs your GameFabric Armadas or Vessels.

The following features are provided:

• Parameter templating,
• Configuration file templating,
• Shutdown handling,
• Log tailing, and
• Crash reporting.

Features

Templating

The GSW uses the standard Go templating syntax and its basic functionality as described here.

Command-line arguments

The GSW can be configured to generate a templated command to execute the game server with. The available templating variables are:

Placeholder	Type	Description
{{.GameServerIP}}	string	The IP given by Agones to the game server.
{{.GameServerPort}}	uint16	The port given by Agones to the game server. Defaults to the port named game, or if there is no port with that name, to the first port found. A different name can be configured using --ports.primary.
{{.Ports}}	map[string]uint16	The known game server ports.
{{.Env}}	map[string]string	The environment variables.

Example:

gsw -- /app/gameserver --port={{ .GameServerPort }} --query-port={{ .Ports.query }} --servername={{ .Env.POD_NAME }}

Configuration Files

The GSW can be configured to generate a templated configuration file. It needs a template file as an input, which must be available within the gswrapper's container, and an output file path. The available templating variables are the same as the ones for command-line arguments.

Command-line argument	Environment variable	Description
--config.template-path	CONFIG_TEMPLATE_PATH	Path at which to write the game server configuration file.
--config.output-path	CONFIG_OUTPUT_PATH	Path to the configuration file template.

Example:

# template.yaml
gameserver:
  ip: "{{ .GameServerIP }}"
  port: "{{ .GameServerPort }}"
  {{- if .Env.POD_NAME }}
  servername: "{{ .Env.POD_NAME }}"
  {{- end }}

gsw --config.template-path=template.yaml --config.output-path=config.yaml -- /app/gameserver --config=config.yaml

Log tailing

The GSW also supports tailing log files and printing them on stdout using the wrapper's logger.

Command-line argument	Environment variable	Description
--tail-log.paths	TAIL_LOG_PATHS	Paths from which to tail log files. Can be passed multiple times.

Example:

gsw --tail-log.paths=gameserver.log --tail-log.paths=error.log -- /app/gameserver

Shutdown handling

The GSW can also manage the lifetime of the game server by initiating the shutdown for different phases and after a configured duration.

This can be useful to force the shutdown of stuck game servers or allow compaction of the fleet.

Command-line argument	Environment variable	Description
--shutdown.scheduled	SHUTDOWN_SCHEDULED	Shutdown when the game server has been Scheduled for the given duration (default: 0s, disabled).
--shutdown.ready	SHUTDOWN_READY	Shutdown when the game server has been Ready for the given duration (default: 0s, disabled).
--shutdown.allocated	SHUTDOWN_ALLOCATED	Shutdown when the game server has been Allocated for the given duration (default: 0s, disabled).

Example:

gsw --shutdown.ready=1h --shutdown.allocated=24h -- /app/gameserver

Crash reporting

Lastly, the crash handler can be configured to run an executable automatically in the event of a server crash.

Command-line argument	Environment variable	Description
--crashhandler.exec	CRASHHANDLER_EXEC	Path to the crash handler executable.
--crashhandler.args	CRASHHANDLER_ARGS	Crash handler arguments. Can be passed multiple times.
--crashhandler.max-execution-time	CRASHHANDLER_MAX_EXECUTION_TIME	Timeout after which the crash handler should be aborted (default: 30m). Please add the time unit, as the default is nanoseconds.

Example:

gsw --crashhandler.exec=crash.sh --crashhandler.args="{{ .GameServerIP }}" --crashhandler.args="{{ .GameServerPort }}" --crashhandler.max-execution-time=5m