mc-monitor: A Go repository from itzg

Command/agent to monitor the status of Minecraft servers

Install module

go get github.com/itzg/go-mc-status

Usage

Subcommands:
	flags            describe all known top-level flags
	help             describe subcommands and their syntax
	version          Show version and exit

Subcommands for monitoring:
	export-for-prometheus  Registers an HTTP metrics endpoints for Prometheus export
	gather-for-telegraf  Periodically gathers to status of one or more Minecraft servers and sends metrics to telegraf over TCP using Influx line protocol
	collect-otel Periodically collects to status of one or more Minecraft servers and sends metrics to an OpenTelemetry Collector using the gRPC protocol

Subcommands for status:
	status           Retrieves and displays the status of the given Minecraft server
	status-bedrock   Retrieves and displays the status of the given Minecraft Bedrock Dedicated server

Usage for any of the sub-commands can be displayed by add --help after each, such as:

mc-monitor status --help

status

  -host string
    	hostname of the Minecraft server (env MC_HOST) (default "localhost")
  -json
    	output server status as JSON
  -port int
    	port of the Minecraft server (env MC_PORT) (default 25565)
  -retry-interval duration
    	if retry-limit is non-zero, status will be retried at this interval (default 10s)
  -retry-limit int
    	if non-zero, failed status will be retried this many times before exiting
  -show-player-count
    	show just the online player count
  -skip-readiness-check
    	returns success when pinging a server without player info, or with a max player count of 0
  -timeout duration
    	the timeout the ping can take as a maximum (default 15s)
  -use-mc-utils
    	(experimental) try using mcutils to query the server
  -use-proxy
    	supports contacting Bungeecord when proxy_protocol enabled
  -use-server-list-ping
    	indicates the legacy, server list ping should be used for pre-1.12

status-bedrock

  -host string
    	 (default "localhost")
  -port int
    	 (default 19132)
  -retry-interval duration
    	if retry-limit is non-zero, status will be retried at this interval (default 10s)
  -retry-limit int
    	if non-zero, failed status will be retried this many times before exiting

export-for-prometheus

  -bedrock-servers host:port
    	one or more host:port addresses of Bedrock servers to monitor, when port is omitted 19132 is used (env EXPORT_BEDROCK_SERVERS)
  -port int
    	HTTP port where Prometheus metrics are exported (env EXPORT_PORT) (default 8080)
  -servers host:port
    	one or more host:port addresses of Java servers to monitor, when port is omitted 25565 is used (env EXPORT_SERVERS)
  -timeout duration
    	timeout when checking each servers (env TIMEOUT) (default 1m0s)

gather-for-telegraf

  -interval duration
    	gathers and sends metrics at this interval (env GATHER_INTERVAL) (default 1m0s)
  -servers host:port
    	one or more host:port addresses of servers to monitor (env GATHER_SERVERS)
  -telegraf-address host:port
    	host:port of telegraf accepting Influx line protocol (env GATHER_TELEGRAF_ADDRESS) (default "localhost:8094")

collect-otel

  -bedrock-servers host:port
    	one or more host:port addresses of Bedrock servers to monitor, when port is omitted 19132 is used (env EXPORT_BEDROCK_SERVERS)
  -interval duration
    	Collect and sends OpenTelemetry data at this interval (env EXPORT_INTERVAL) (default 10s)
  -otel-collector-endpoint string
    	OpenTelemetry gRPC endpoint to export data (env EXPORT_OTEL_COLLECTOR_ENDPOINT) (default "localhost:4317")
  -otel-collector-timeout duration
    	Timeout for collecting OpenTelemetry data (env EXPORT_OTEL_COLLECTOR_TIMEOUT) (default 35s)
  -servers host:port
    	one or more host:port addresses of Java servers to monitor, when port is omitted 25565 is used (env EXPORT_SERVERS)

Examples

Checking the status of a server

To check the status of a Java edition server:

docker run -it --rm itzg/mc-monitor status --host mc.hypixel.net

To check the status of a Bedrock Dedicated server:

docker run -it --rm itzg/mc-monitor status-bedrock --host play.fallentech.io

where exit code will be 0 for success or 1 for failure.

Workarounds for some status errors

Some Forge servers may cause a string length out of bounds error during status messages due to how the FML2 protocol bundles the entire modlist for client compatibility check. If there are issues with status failing when it otherwise should work, you can try out the experimental --use-mc-utils flag below (enables the mcutils protocol library):

docker run -it --rm itzg/mc-monitor status --use-mc-utils --host play.fallentech.io

Monitoring a server with Telegraf

The following example is provided in examples/mc-monitor-telegraf

Given the telegraf config file:

[[inputs.socket_listener]]
  service_address = "tcp://:8094"

[[outputs.file]]
  files = ["stdout"]

...and a Docker composition of telegraf and mc-monitor services:

version: '3'

services:
  telegraf:
    image: telegraf:1.13
    volumes:
    - ./telegraf.conf:/etc/telegraf/telegraf.conf:ro
  monitor:
    image: itzg/mc-monitor
    command: gather-for-telegraf
    environment:
      GATHER_INTERVAL: 10s
      GATHER_TELEGRAF_ADDRESS: telegraf:8094
      GATHER_SERVERS: mc.hypixel.net

The output of the telegraf service will show metric entries such as:

minecraft_status,host=mc.hypixel.net,port=25565,status=success response_time=0.172809649,online=51201i,max=90000i 1576971568953660767
minecraft_status,host=mc.hypixel.net,port=25565,status=success response_time=0.239236074,online=51198i,max=90000i 1576971579020125479
minecraft_status,host=mc.hypixel.net,port=25565,status=success response_time=0.225942383,online=51198i,max=90000i 1576971589006821324

Monitoring a server with Prometheus

When using the export-for-prometheus subcommand, mc-monitor will serve a Prometheus exporter on port 8080, by default, that collects Minecraft server metrics during each scrape of /metrics.

The sub-command accepts the following arguments, which can also be viewed using --help:

  -bedrock-servers host:port
    	one or more host:port addresses of Bedrock servers to monitor, when port is omitted 19132 is used (env EXPORT_BEDROCK_SERVERS)
  -port int
    	HTTP port where Prometheus metrics are exported (env EXPORT_PORT) (default 8080)
  -servers host:port
    	one or more host:port addresses of Java servers to monitor, when port is omitted 25565 is used (env EXPORT_SERVERS)

The following metrics are exported

minecraft_status_healthy
minecraft_status_response_time_seconds
minecraft_status_players_online_count
minecraft_status_players_max_count

with the labels

server_host
server_port
server_edition : java or bedrock
server_version

An example Docker composition is provided in examples/mc-monitor-prom, which was used to grab the following screenshot:

Monitoring a server with Open Telemetry

Open Telemetry is a vendor-agnostic way to receive, process and export telemetry data. In this context, monitoring a Minecraft Server with Open Telemetry requires a running Open Telemetry Collector to receive the exported data. An example on how to initialize it can be found in examples/mc-monitor-otel.

Once you run the mc-monitor application using the collect-otel subcommand, mc-monitor will create the necessary [instrumentation] (https://opentelemetry.io/docs/languages/go/instrumentation/#metrics) to export the metrics to the collector through the gRPC protocol.

The Collector will receive and process the data, sending the metrics to any of the supported backends. In our example, you will find the necessary configurations to export metrics through Prometheus.

The collect-otel sub-command accepts the following arguments, which can also be viewed using --help:

  -servers host:port
    	one or more host:port addresses of Java servers to monitor, when port is omitted 25565 is used (env EXPORT_SERVERS)
  -bedrock-servers host:port
    	one or more host:port addresses of Bedrock servers to monitor, when port is omitted 19132 is used (env EXPORT_BED_ROCK_SERVERS)
  -interval duration
    	Collect and sends OpenTelemetry data at this interval (env EXPORT_INTERVAL) (default 10s)

  -otel-collector-endpoint string
    	OpenTelemetry gRPC endpoint to export data (env EXPORT_OTEL_COLLECTOR_ENDPOINT) (default "localhost:4317")
  -otel-collector-timeout duration
    	Timeout for collecting OpenTelemetry data (env EXPORT_OTEL_COLLECTOR_TIMEOUT) (default 35s)

The following metrics are exported

minecraft_status_healthy
minecraft_status_response_time_seconds
minecraft_status_players_online_count
minecraft_status_players_max_count

with the labels

server_host
server_port
server_edition : java or bedrock
server_version

An example Docker composition is provided in examples/mc-monitor-otel.