hunter-agent function list

[moooofly]

Core Features

• The role of hunter-agent:
  • From the perspective of opencensus exporter, it is a grpc server.
  • From the perspective of kafka broker, it is a kafka producer.
• Prometheus metrics support.
  • docker/go-metrics
  • prometheus/client_golang
• Communication method support:
  • Unix Domain Socket
  • Tcp Socket
• Flow control
  • a basic flow control by channel buffer size.
  • fulfill flow-control channel length dynamic updating (issue#8)
  • more complicated flow-control mechanism (issue#9)
• Complicated signal process.
  • Configuration reload by SIGHUP.
  • Dump stacks of all goroutines by SIGUSR1.
  • Ignore SIGPIPE.
  • Call custom cleanup function, then terminate process by SIGINT/SIGTERM.
  • Cause an exit without cleanup, with a goroutine dump preceding exit by SIGQUIT.
• Add more here...

Optional Features

• glide support
• run as daemon
  • by systemd
  • by sevlyar/go-daemon
  • by fiorix/go-daemon
• Kafka connection issues:
  • auth
  • SSL
• Control plane
  • Pass specific requests (whitelist).
  • Block specific requests (blacklist).
  • Rewrite specific requests.
• Keepalive probe and/or Healthy check.
• Run integration test locally by docker-compose.
• A CLI client to interact with hunter-agent.
• add docker-entrypoint.sh support. (issues#4)
• Port use:
  • The listen port used by grpc server.
  • The random port used by kafka producer.
• Add more here...

[moooofly]

Unix Domain Socket v.s. Network Socket

A Unix domain socket is an inter-process communication mechanism that allows bidirectional data exchange between processes running on the same machine.

IP sockets (especially TCP/IP sockets) are a mechanism allowing communication between processes over the network. In some cases, you can use TCP/IP sockets to talk with processes running on the same computer (by using the loopback interface).

UNIX domain sockets know that they’re executing on the same system, so they can avoid some checks and operations (like routing); which makes them faster and lighter than IP sockets. So if you plan to communicate with processes on the same host, this is a better option than IP sockets.

UNIX domain sockets are subject to file system permissions, while TCP sockets can be controlled only on the packet filter level.

When the server and client benchmark programs run on the same box, both the TCP/IP loopback and unix domain sockets can be used. Depending on the platform, unix domain sockets can achieve around 50% more throughput than the TCP/IP loopback (on Linux for instance). The default behavior of redis-benchmark is to use the TCP/IP loopback.

list command:

netstat -naxp

---

Ref:

• Unix domain socket
• Network socket
• unix domain sockets vs. internet sockets
• What's the difference between Unix socket and TCP/IP socket?
• rigtorp/ipc-bench -- Latency benchmarks of Unix IPC mechanisms.
• Factors impacting Redis performance

[moooofly]

Daemon or not Daemon, is a question

hunter-agent does not daemonize on its own. For production usage, it is recommended to launch in a process supervisor, and drop privileges as appropriate.

Examples of supervisors include: daemontools, runit, upstart, launchd, systemd, and many more.

For the reasoning behind lack of daemonization, see daemontools/why. In addition, the code is much simpler because of it.

other: 《golang 应用的 daemon 问题》 -- private