Constrainer

There may be some cases where you want to prevent some combination of Chaos Monkey terminations, but the configuration options aren't flexible enough for your use case.

You can define a custom constrainer to do this.

As an example, let's say you wanted to disallow any terminations for apps that contain "foo" as a substring.

package constrainer

import (
	"github.com/Netflix/chaosmonkey/deps"
	"github.com/Netflix/chaosmonkey/config"
	"github.com/Netflix/chaosmonkey/schedule"
    "strings"
)

func init() {
    deps.GetConstrainer = getConstrainer()
}

type noFoo struct {}

func getConstrainer(cfg *config.Monkey) (schedule.Constrainer, error) {
    return noFoo{}, nil
}

func (n noFoo) Filter(s schedule.Schedule) schedule.Schedule {
	result := schedule.New()
	for _, entry := range s.Entries() {
        if !strings.Contains(entry.Group.App(), "foo") {
            result.Add(entry.Time, entry.Group)
        }
    }
    return result
}

See the Plugins page for info on how to build a custom version of Chaos Monkey with your plugin.