| /* |
| Copyright 2018 The Kubernetes Authors. |
| |
| Licensed under the Apache License, Version 2.0 (the "License"); |
| you may not use this file except in compliance with the License. |
| You may obtain a copy of the License at |
| |
| http://www.apache.org/licenses/LICENSE-2.0 |
| |
| Unless required by applicable law or agreed to in writing, software |
| distributed under the License is distributed on an "AS IS" BASIS, |
| WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| See the License for the specific language governing permissions and |
| limitations under the License. |
| */ |
| |
| package util |
| |
| import ( |
| "strings" |
| |
| "github.com/pkg/errors" |
| |
| utilsexec "k8s.io/utils/exec" |
| ) |
| |
| // TODO: add support for detecting the cgroup driver for CRI other than |
| // Docker. Currently only Docker driver detection is supported: |
| // Discussion: |
| // https://github.com/kubernetes/kubeadm/issues/844 |
| |
| // GetCgroupDriverDocker runs 'docker info' to obtain the docker cgroup driver |
| func GetCgroupDriverDocker(execer utilsexec.Interface) (string, error) { |
| info, err := callDockerInfo(execer) |
| if err != nil { |
| return "", err |
| } |
| return getCgroupDriverFromDockerInfo(info) |
| } |
| |
| func validateCgroupDriver(driver string) error { |
| if driver != "cgroupfs" && driver != "systemd" { |
| return errors.Errorf("unknown cgroup driver %q", driver) |
| } |
| return nil |
| } |
| |
| // TODO: Docker 1.13 has a new way to obatain the cgroup driver: |
| // docker info -f "{{.CgroupDriver}} |
| // If the minimum supported Docker version in K8s becomes 1.13, move to |
| // this syntax. |
| func callDockerInfo(execer utilsexec.Interface) (string, error) { |
| out, err := execer.Command("docker", "info").Output() |
| if err != nil { |
| return "", errors.Wrap(err, "cannot execute 'docker info'") |
| } |
| return string(out), nil |
| } |
| |
| func getCgroupDriverFromDockerInfo(info string) (string, error) { |
| lineSeparator := ": " |
| prefix := "Cgroup Driver" |
| for _, line := range strings.Split(info, "\n") { |
| if !strings.Contains(line, prefix+lineSeparator) { |
| continue |
| } |
| lineSplit := strings.Split(line, lineSeparator) |
| // At this point len(lineSplit) is always >= 2 |
| driver := lineSplit[1] |
| if err := validateCgroupDriver(driver); err != nil { |
| return "", err |
| } |
| return driver, nil |
| } |
| return "", errors.New("cgroup driver is not defined in 'docker info'") |
| } |