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13bd08b15b
This PR refactors the code path in Client startup for setting up the cpuset cgroup manager (non-linux systems not affected). Before, there was a logic bug where we would try to read the cpuset.cpus.effective cgroup interface file before ensuring nomad's parent cgroup existed. Therefor that file would not exist, and the list of useable cpus would be empty. Tasks started thereafter would not have a value set for their cpuset.cpus. The refactoring fixes some less than ideal coding style. Instead we now bootstrap each cpuset manager type (v1/v2) within its own constructor. If something goes awry during bootstrap (e.g. cgroups not enabled), the constructor returns the noop implementation and logs a warning. Fixes #14229
86 lines
2.4 KiB
Go
86 lines
2.4 KiB
Go
package cgutil
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import (
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"context"
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"fmt"
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"path/filepath"
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"strings"
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"github.com/hashicorp/nomad/lib/cpuset"
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"github.com/hashicorp/nomad/nomad/structs"
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)
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const (
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// CgroupRoot is hard-coded in the cgroups specification.
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// It only applies to linux but helpers have references to it in driver(s).
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CgroupRoot = "/sys/fs/cgroup"
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)
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// CpusetManager is used to setup cpuset cgroups for each task.
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type CpusetManager interface {
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// Init should be called before the client starts running allocations. This
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// is where the cpuset manager should start doing background operations.
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Init()
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// AddAlloc adds an allocation to the manager
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AddAlloc(alloc *structs.Allocation)
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// RemoveAlloc removes an alloc by ID from the manager
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RemoveAlloc(allocID string)
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// CgroupPathFor returns a callback for getting the cgroup path and any error that may have occurred during
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// cgroup initialization. The callback will block if the cgroup has not been created
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CgroupPathFor(allocID, taskName string) CgroupPathGetter
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}
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type NoopCpusetManager struct{}
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func (n NoopCpusetManager) Init() {
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}
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func (n NoopCpusetManager) AddAlloc(alloc *structs.Allocation) {
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}
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func (n NoopCpusetManager) RemoveAlloc(allocID string) {
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}
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func (n NoopCpusetManager) CgroupPathFor(allocID, task string) CgroupPathGetter {
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return func(context.Context) (string, error) { return "", nil }
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}
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// CgroupPathGetter is a function which returns the cgroup path and any error which
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// occurred during cgroup initialization.
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//
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// It should block until the cgroup has been created or an error is reported.
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type CgroupPathGetter func(context.Context) (path string, err error)
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type TaskCgroupInfo struct {
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CgroupPath string
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RelativeCgroupPath string
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Cpuset cpuset.CPUSet
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Error error
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}
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// identity is the "<allocID>.<taskName>" string that uniquely identifies an
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// individual instance of a task within the flat cgroup namespace
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type identity string
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func makeID(allocID, task string) identity {
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return identity(fmt.Sprintf("%s.%s", allocID, task))
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}
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func makeScope(id identity) string {
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return string(id) + ".scope"
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}
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// SplitPath determines the parent and cgroup from p.
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// p must contain at least 2 elements (parent + cgroup).
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//
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// Handles the cgroup root if present.
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func SplitPath(p string) (string, string) {
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p = strings.TrimPrefix(p, CgroupRoot)
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p = strings.Trim(p, "/")
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parts := strings.Split(p, "/")
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return parts[0], "/" + filepath.Join(parts[1:]...)
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}
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