megos

Go(lang) client library for accessing an Apache Mesos cluster.

Features

• Determine the Mesos leader
• Get the current state of every mesos node (master or slave)
• Retrieve stdout and stderr of tasks
• Covered with unit tests

Installation

It is go gettable

$ go get github.com/andygrunwald/megos

(optional) to run unit / example tests:

$ cd $GOPATH/src/github.com/andygrunwald/megos
$ go test -v ./...

API

Please have a look at the GoDoc documentation for a detailed API description.

Examples / use cases

A (small) list of usecases how this library can be used:

• Determine the leader of a Mesos cluster
• Get a list of all completed Mesos tasks
• Get the stdout and stderr of a failed mesos task
• Get the statistics and push it to a different backend

Further more a few examples how the API can be used and the code looks like.

Determine the leader node

node1, _ := url.Parse("http://192.168.1.120:5050/")
node2, _ := url.Parse("http://192.168.1.122:5050/")

mesos := megos.NewClient([]*url.URL{node1, node2}, nil)
leader, err := mesos.DetermineLeader()
if err != nil {
	panic(err)
}

fmt.Println(leader)
// Output:
// master@192.168.1.122:5050

Get the version of Mesos

node1, _ := url.Parse("http://192.168.1.120:5050/")
node2, _ := url.Parse("http://192.168.1.122:5050/")

mesos := megos.NewClient([]*url.URL{node1, node2}, nil)
state, err := mesos.GetStateFromCluster()
if err != nil {
	panic(err)
}

fmt.Printf("Mesos v%s", state.Version)
// Output:
// Mesos v0.26.0

Get stdout and stderr of a task

Get stdout and stderr from a task of the chronos framework. Error checks are dropped for simplicity.

node1, _ := url.Parse("http://192.168.1.120:5050/")
node2, _ := url.Parse("http://192.168.1.122:5050/")
mesos := megos.NewClient([]*url.URL{node1, node2}, nil)

frameworkPrefix := "chronos"
taskID := "ct:1444578480000:0:example-chronos-task:"

mesos.DetermineLeader()
state, _ := mesos.GetStateFromLeader()

framework, _ := mesos.GetFrameworkByPrefix(state.Frameworks, frameworkPrefix)
task, _ := mesos.GetTaskByID(framework.CompletedTasks, taskID)

slave, _ := mesos.GetSlaveByID(state.Slaves, task.SlaveID)

pid, _ := mesos.ParsePidInformation(slave.PID)
slaveState, _ := mesos.GetStateFromPid(pid)

framework, _ = mesos.GetFrameworkByPrefix(slaveState.CompletedFrameworks, frameworkPrefix)
executor, _ := mesos.GetExecutorByID(framework.CompletedExecutors, taskID)

stdOut, _ := mesos.GetStdOutOfTask(pid, executor.Directory)
stdErr, _ := mesos.GetStdErrOfTask(pid, executor.Directory)

fmt.Println(string(stdOut))
fmt.Println("================")
fmt.Println(string(stdErr))
// Output:
// Registered executor on 192.168.1.123
// Starting task ct:1444578480000:0:example-chronos-task:
// sh -c 'MY COMMAND'
// Forked command at 10629
// ...
// ================
// I1011 17:48:00.390614 10602 exec.cpp:132] Version: 0.22.1
// I1011 17:48:00.532158 10618 exec.cpp:206] Executor registered on slave 20150603-103119-2046951690-5050-24382-S1

Version compatibility

This library was tested with Apache Mesos in version 0.26.0. In theory this should work with versions >= v0.25.x.

In version 0.25.x they renamed various API endpoints (like state.json to /state). See Upgrading Mesos - Upgrading from 0.24.x to 0.25.x for details. This is the reason why we support no lower versions of Mesos.

Other/Similar projects

• boldfield/go-mesos: A client for discovering information about a Mesos exposed via HTTP API
• antonlindstrom/mesos_stats: Statistics definition for Mesos /monitor/statistics.json
• Clever/marathon-stats: A simple container which queries marathon and mesos for stats about their current state, and logs these stats to stderr
• bolcom/mesos_metrics: Go definitions for the Mesos {master}:5050/metrics/snapshot and {slave}:5051/metrics/snapshot endpoints

Contribution

• You have a question?
• Don`t know if a feature is supported?
• Want to implement a new feature, but don`t know how?
• You like the library and use it for your implementation / use case?
• You found a bug or incompatibility?
• Something is not working as expected?

Feel free to open a new issue. I will be happy to answer them and try to help you. It might be useful to add as much information as possible into the issue like Mesos version, example URL, (parts) of your code and the expected and current behaviour.

License

This project is released under the terms of the MIT license.