Mesos Attributes & Resources

The Mesos system has two basic methods to describe the slaves that comprise a cluster. One of these is managed by the Mesos master, the other is simply passed onwards to the frameworks using the cluster.

Types

The types of values that are supported by Attributes and Resources in Mesos are scalar, ranges, sets and text.

The following are the definitions of these types:

scalar : floatValue

floatValue : ( intValue ( "." intValue )? ) | ...

intValue : [0-9]+

range : "[" rangeValue ( "," rangeValue )* "]"

rangeValue : scalar "-" scalar

set : "{" text ( "," text )* "}"

text : [a-zA-Z0-9_/.-]

Attributes

Attributes are key-value pairs (where value is optional) that Mesos passes along when it sends offers to frameworks. An attribute value supports 3 different types: scalar, range or text.

attributes : attribute ( ";" attribute )*

attribute : text ":" ( scalar | range | text )

Resources

The Mesos system can manage 3 different types of resources: scalars, ranges, and sets. These are used to represent the different resources that a Mesos slave has to offer. For example, a scalar resource type could be used to represent the amount of memory on a slave. Resources can be specified either with a JSON array or a semicolon-delimited string of key:value pairs. If, after examining the examples below, you have questions about the format of the JSON, inspect the Resource protobuf message definition in include/mesos/mesos.proto.

As JSON:

[
  {
    "name": "<resource_name>",
    "type": "SCALAR",
    "scalar": {
      "value": <resource_value>
    }
  },
  {
    "name": "<resource_name>",
    "type": "RANGES",
    "ranges": {
      "range": [
        {
          "begin": <range_beginning>,
          "end": <range_ending>
        },
        ...
      ]
    }
  },
  {
    "name": "<resource_name>",
    "type": "SET",
    "set": {
      "item": [
        "<first_item>",
        ...
      ]
    },
    "role": "<role_name>"
  },
  ...
]

As a list of key:value pairs:

resources : resource ( ";" resource )*

resource : key ":" ( scalar | range | set )

key : text ( "(" resourceRole ")" )?

resourceRole : text | "*"

Note that resourceRole must be one of the roles that was defined when the Mesos master was started.

Predefined Uses & Conventions

The Mesos master has a few resources that it pre-defines in how it handles them. At the current time, this list consist of:

• cpus
• mem
• disk
• ports

In particular, a slave without cpus and mem resources will never have its resources advertised to any frameworks. Also, the Master's user interface interprets the scalars in mem and disk in terms of MB. IE: the value 15000 is displayed as 14.65GB.

Examples

Here are some examples for configuring the Mesos slaves.

--resources='cpus:24;mem:24576;disk:409600;ports:[21000-24000,30000-34000];bugs(debug_role):{a,b,c}'

--resources='[{"name":"cpus","type":"SCALAR","scalar":{"value":24}},{"name":"mem","type":"SCALAR","scalar":{"value":24576}},{"name":"disk","type":"SCALAR","scalar":{"value":409600}},{"name":"ports","type":"RANGES","ranges":{"range":[{"begin":21000,"end":24000},{"begin":30000,"end":34000}]}},{"name":"bugs","type":"SET","set":{"item":["a","b","c"]},"role":"debug_role"}]'

--attributes='rack:abc;zone:west;os:centos5;level:10;keys:[1000-1500]'

Or given a file resources.txt containing the following:

[
  {
    "name": "cpus",
    "type": "SCALAR",
    "scalar": {
      "value": 24
    }
  },
  {
    "name": "mem",
    "type": "SCALAR",
    "scalar": {
      "value": 24576
    }
  },
  {
    "name": "disk",
    "type": "SCALAR",
    "scalar": {
      "value": 409600
    }
  },
  {
    "name": "ports",
    "type": "RANGES",
    "ranges": {
      "range": [
        {
          "begin": 21000,
          "end": 24000
        },
        {
          "begin": 30000,
          "end": 34000
        }
      ]
    }
  },
  {
    "name": "bugs",
    "type": "SET",
    "set": {
      "item": [
        "a",
        "b",
        "c"
      ]
    },
    "role": "debug_role"
  }
]

You can do:

$ path/to/mesos-slave --resources=file:///path/to/resources.txt ...

In this case, we have five resources of three different types: scalars, a range, and a set. There are scalars called cpus, mem and disk, a range called ports, and a set called bugs. bugs is assigned to the role debug_role, while the other resources do not specify a role and are thus assigned to the default role.

Note: the "default role" can be set by the --default_role flag.

• scalar called cpus, with the value 24
• scalar called mem, with the value 24576
• scalar called disk, with the value 409600
• range called ports, with values 21000 through 24000 and 30000 through 34000 (inclusive)
• set called bugs, with the values a, b and c, assigned to the role debug_role

In the case of attributes, we end up with five attributes:

• rack with text value abc
• zone with text value west
• os with text value centos5
• level with scalar value 10
• keys with range value 1000 through 1500 (inclusive)