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CPU and Memory Resource Limits

Overview

This feature adds the ability to specify CPU and memory limits for Docker containers in buildrunner configurations. These limits are passed to Docker's create_host_config method, allowing fine-grained control over container resource usage.

Configuration Options

The following resource limit fields are available for both run steps and service containers:

  • mem-limit: Memory limit (string like "512m", "1g" or integer in bytes)
  • cpu-shares: CPU shares (relative weight, default is 1024)
  • cpu-period: CPU period in microseconds (default is 100000)
  • cpu-quota: CPU quota in microseconds

Usage Examples

Memory Limit

steps:
  my-step:
    run:
      image: ubuntu:20.04
      mem-limit: "512m"  # or 536870912 for bytes
      cmd: echo "Running with memory limit"

CPU Limits

steps:
  my-step:
    run:
      image: ubuntu:20.04
      cpu-shares: 512      # Relative weight (default 1024)
      cpu-period: 100000   # Period in microseconds
      cpu-quota: 50000     # Quota in microseconds (50% of one CPU)
      cmd: echo "Running with CPU limits"

Combined Limits

steps:
  my-step:
    run:
      image: ubuntu:20.04
      mem-limit: "1g"
      cpu-shares: 1024
      cpu-period: 100000
      cpu-quota: 100000
      cmd: echo "Running with all limits"

Service Container Limits

steps:
  my-step:
    run:
      image: ubuntu:20.04
      services:
        database:
          image: postgres:13
          mem-limit: "256m"
          cpu-shares: 512
          env:
            POSTGRES_PASSWORD: example
      cmd: echo "Main container with limited database service"

Docker Resource Limit Parameters

Memory Limit (mem-limit)

  • Accepts: String (e.g., "512m", "1g", "2g") or integer (bytes)
  • Description: Sets the maximum amount of memory the container can use
  • Behavior: Docker will enforce this limit and may kill the container if exceeded

CPU Shares (cpu-shares)

  • Accepts: Integer
  • Default: 1024
  • Description: Relative weight for CPU time allocation
  • Behavior: Higher values get more CPU time when there's contention

CPU Period (cpu-period)

  • Accepts: Integer (microseconds)
  • Default: 100000 (100ms)
  • Description: Defines the period for CPU quota enforcement

CPU Quota (cpu-quota)

  • Accepts: Integer (microseconds)
  • Description: Limits CPU time within the period
  • Example: quota=50000, period=100000 = 50% of one CPU core

Implementation Details

Configuration Model

Resource limit fields are defined in the RunAndServicesBase class in buildrunner/config/models_step.py. These fields are inherited by both StepRun and Service configurations.

Docker Runner

The DockerRunner.start() method in buildrunner/docker/runner.py accepts resource limit parameters and passes them to Docker's create_host_config method.

Run Task Integration

The run task layer in buildrunner/steprunner/tasks/run.py extracts resource limits from step and service configurations and passes them to the Docker runner for both main containers and service containers.

See Also

  • :doc:`global-configuration` - Global buildrunner configuration options
  • examples/resource-limits-example.yaml - Complete working examples