Macros¶

The dcos-perf-test-driver implements a minimal template engine that can be used to provide parametric configuration to your test. For example, if you are launching a command-line application and some parameters need to change over time you can use the {{parameter_name}} macro expression:

channels:
  - class: channel.CmdlineChannel
    cmdline: "benchmark_users --users={{users}}"

Such macros can appear at any place in your YAML configuration and they will be evaluated to the definition or parameter with the given name. Refer to Value sources for more details.

Note

Be aware that macros can only appear in YAML values and not in the key names. For instance, the following expression is invalid:

config:
  "{{prefix}}_run": "always"

Value sources¶

The values of the macros are coming from various sources, in the following order:

Definitions in the configuration file through the define statement.
Definitions given by the command-line through the –define argument.
The test parameters and their values during the current test phase.

Default values¶

It is possible to provide a default value to your macros using the {{macro|default}} expression. For example:

reporters:
  - class: reporter.PostgRESTReporter
    url: "{{reporter_url|http://127.0.0.1:4000}}"

Functions¶

It is possible to call a small set of functions in your macro. The following functions are available:

uuid¶

Compute a unique GUID ID. For example:

channels:
  - class: channel.CmdlineChannel
    cmdline: "ctl useradd --name=user-{{uuid()}}"

date(format)¶

Compose a date expression from the current time and date. For example:

reporters:
  - class: reporter.S3Reporter
    path: "metrics/{{date(%Y%m%d)}}-results.json"

The format argument is exactly what python’s strftime accepts.

safepath(expression)¶

Replaces all the ‘unsafe’ characters for a path expression with ‘_’

reporters:
  - class: reporter.S3Reporter
    path: "metrics/{{safepath(test_name)}}-results.json"

The expression argument can be any legit macro expression.

eval(expression)¶

Evaluates the given expression as a python expression.

policies:
  - class: policy.SimplePolicy
    value: "{{eval(apps * tasks)}}"

Metadata as macros¶

In some cases (for example in the reporter definitions) it might be needed to evaluate the value of a metadata. You can do so by using the {{meta:name}} syntax. For example:

reporters:
  - class: reporter.S3Reporter
    bucket: marathon-artifacts
    path: "metrics/{{meta:version}}-results.json"