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 value24
- scalar called
mem
, with the value24576
- scalar called
disk
, with the value409600
- range called
ports
, with values21000
through24000
and30000
through34000
(inclusive) - set called
bugs
, with the valuesa
,b
andc
, assigned to the roledebug_role
In the case of attributes, we end up with five attributes:
rack
with text valueabc
zone
with text valuewest
os
with text valuecentos5
level
with scalar value 10keys
with range value1000
through1500
(inclusive)