The regulator of your Docker Swarm cluster
Project description
Swarm Regulator
Regulate your Docker Swarm cluster, according to YOUR rules. Use async
Python functions to enforce rules like service placement and resource management on your Docker Swarm.
Concepts
Consumer
Each regulator is based on top of a single consumer. The consumer responds to Docker events and instruments all components of the regulator.
Conditions
A regulator needs to know when to apply its rules. This is what conditions are for. Conditions help us know when should a rule be applied on a Docker Swarm entity. In brief, a condition is a Python function (or callable) that accepts a Docker Swarm entity as a single argument and returns True
when the rule should run, and False
when it shouldn't.
🙌 Heads up: In order to avoid infinite loops, a confition that initially returns True
, should return False
, when it gets the regulated entity as an argument. If this is not the case, the rule is being ignored.
Rules
Rules simply do the job. Rules are async
Python functions that accept a Docker Swarm entity as an argument and return it modified, so it complies with the business logic we intend to enforce on our Docker Swarm cluster.
Requirements
- Python 3.8+
- Docker Swarm Mode cluster
Install
pipenv
pipenv install swarm-regulator
poetry
poetry add swarm-regulator
pip
pip install swarm-regulator
Run
- Create a Python file (e.g.
regulator.py
) - Import the
consumer
from theswarm_regulator
package - Register your rules that will run according to given conditions
- Run your regulator
Example
regulator.py
from swarm_regulator import consumer
def _extract_constraints(service_spec):
return service_spec["TaskTemplate"]["Placement"].get("Constraints", [])
def has_not_constraints(service_spec) -> bool:
constraints = _extract_constraints(service_spec)
return not len(constraints)
async def do_not_schedule_on_gpu(service_spec):
constraints = _extract_constraints(service_spec) + ["node.labels.gpu!=true"]
service_spec["TaskTemplate"]["Placement"]["Constraints"] = constraints
return service_spec
consumer.register_rule(
"service", has_not_constraints, do_not_schedule_on_gpu,
)
consumer.run()
Run
python regulator.py
Project details
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