Snapteld crashes when a task for a stream collector is created

[ericho]

Trying to create the following task snapteld crashes. I'm using version 1.2.0 on Ubuntu 16.04

{
    "version" : 1,
    "schedule" : {
        "type" : "simple",
        "interval": "5s"
    },
    "workflow": {
        "collect": {
            "metrics": {
                "/random/*": {}
            },
            "config": {},
            "process": null,
            "publish": null
        }
    }
}

These are the steps to reproduce:

$ snapteld -l 1 -t 0

$ snaptel plugin load streaming-example-plugin
$ snaptel task create --task-manifest task.json

After the snaptel task create command the following crash occur in snapteld

DEBU[2017-05-28T10:50:34-05:00] cache miss [/random/integer:1]                _module=routing-cache hits=0 misses=1 namespace=/random/integer:1
DEBU[2017-05-28T10:50:34-05:00] cache miss [/random/float:1]                  _module=routing-cache hits=0 misses=1 namespace=/random/float:1
DEBU[2017-05-28T10:50:34-05:00] cache miss [/random/string:1]                 _module=routing-cache hits=0 misses=1 namespace=/random/string:1
DEBU[2017-05-28T10:50:34-05:00] plugin selected                               _module=control-routing block=select hitcount=0 index=collector:test-rand-streamer:v1:id1 pool size=1 strategy=least-recently-used
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x20 pc=0x62535a]

goroutine 95 [running]:
panic(0xad9b80, 0xc420014100)
	/home/travis/.gimme/versions/go1.7.3.linux.amd64/src/runtime/panic.go:500 +0x1a1
github.com/intelsdi-x/snap/control/plugin/client.(*grpcClient).CollectMetrics(0xc42008a120, 0xc4202ed900, 0x3, 0x4, 0xf24501, 0xc42022c000, 0x0, 0x0, 0x4)
	/home/travis/gopath/src/github.com/intelsdi-x/snap/control/plugin/client/grpc.go:271 +0xda
github.com/intelsdi-x/snap/control.(*availablePlugins).collectMetrics(0xc420176b90, 0xc420183d40, 0x24, 0xc420159500, 0x3, 0x4, 0xc420182930, 0x24, 0x0, 0x0, ...)
	/home/travis/gopath/src/github.com/intelsdi-x/snap/control/available_plugin.go:434 +0x386
github.com/intelsdi-x/snap/control.(*pluginControl).CollectMetrics.func1(0xc42001a180, 0xc420182930, 0x24, 0xc42016b8c0, 0xc42016b800, 0xc420183d40, 0x24, 0xc420159500, 0x3, 0x4)
	/home/travis/gopath/src/github.com/intelsdi-x/snap/control/control.go:979 +0xb2
created by github.com/intelsdi-x/snap/control.(*pluginControl).CollectMetrics
	/home/travis/gopath/src/github.com/intelsdi-x/snap/control/control.go:985 +0xad7

[katarzyna-z]

Thanks for reporting this issue 🐢 Snap shouldn't crash.
Work on streaming feature is still in progress, please see following pull requests: snap#1632 and snap-plugin-lib-go#85.
However you can test how streaming works for now, you need to change type in schedule to "streaming" and use pure REST API to create a task (for now snaptel does not support streaming), see examplary task manifest:

{
  "version": 1,
  "schedule": {
    "type": "streaming"
  },
  "start": true,
  "max-failures": 10,
  "max-collect-duration": "10s",
  "max-metrics-buffer": 4,
  "workflow": {
    "collect": {
      "metrics": {
        "/random/*": {}
      },
      "config": {},
      "process": null,
      "publish": null
    }
  }
}

and exemplary curl command to create a task:

curl -vX POST localhost:8181/v1/tasks -d @task.json --header "Content-Type: application/json"

Using the code from current versions of pull requests snap#1632 and snap-plugin-lib-go#85 I'm able to reproduce this issue using following task manifest:

{
    "version" : 1,
    "schedule" : {
        "type" : "simple",
        "interval": "5s"
    },
    "start": true,
    "max-failures": 10,
    "workflow": {
        "collect": {
            "metrics": {
                "/random/*": {}
            },
            "config": {},
            "process": null,
            "publish": null
        }
    }
}

[ericho]

Hi @katarzyna-z, thank you very much for the workaround. Now I'm able to test my plugin.

I'll be pending of the related PR 😄