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Mesos Attributes & Resources

Mesos has two basic methods to describe the agents 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 three different types: scalar, range or text.

attributes : attribute ( ";" attribute )*

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

Note that setting multiple attributes corresponding to the same key is highly discouraged (and might be disallowed in future), as this complicates attribute- based filtering of offers, both on schedulers side and on the Mesos side.

Resources

Mesos can manage three different types of resources: scalars, ranges, and sets. These are used to represent the different resources that a Mesos agent has to offer. For example, a scalar resource type could be used to represent the amount of memory on an agent. Scalar resources are represented using floating point numbers to allow fractional values to be specified (e.g., “1.5 CPUs”). Mesos only supports three decimal digits of precision for scalar resources (e.g., reserving “1.5123 CPUs” is considered equivalent to reserving “1.512 CPUs”). For GPUs, Mesos only supports whole number values.

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 a valid role name; see the roles documentation for details.

Predefined Uses & Conventions

There are several kinds of resources that have predefined behavior:

  • cpus
  • gpus
  • disk
  • mem
  • ports

Note that disk and mem resources are specified in megabytes. The master’s user interface will convert resource values into a more human-readable format: for example, the value 15000 will be displayed as 14.65GB.

An agent without cpus and mem resources will not have its resources advertised to any frameworks.

Examples

By default, Mesos will try to autodetect the resources available at the local machine when mesos-agent starts up. Alternatively, you can explicitly configure which resources an agent should make available.

Here are some examples of how to configure the resources at a Mesos agent:

--resources='cpus:24;gpus:2;mem:24576;disk:409600;ports:[21000-24000,30000-34000];bugs(debug_role):{a,b,c}'

--resources='[{"name":"cpus","type":"SCALAR","scalar":{"value":24}},{"name":"gpus","type":"SCALAR","scalar":{"value":2}},{"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"}]'

Or given a file resources.txt containing the following:

[
  {
    "name": "cpus",
    "type": "SCALAR",
    "scalar": {
      "value": 24
    }
  },
  {
    "name": "gpus",
    "type": "SCALAR",
    "scalar": {
      "value": 2
    }
  },
  {
    "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-agent --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, gpus, 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 gpus, with the value 2
  • 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

To configure the attributes of a Mesos agent, you can use the --attributes command-line flag of mesos-agent:

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

That will result in configuring the following 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)

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