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api: use singleflight for /info endpoint

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Prevent potential suggestion when many concurrent requests happen on
the /info endpoint. It's worth noting that with this change,
requests to the endpoint while another request is still in flight
will share the results, hence might be slightly incorrect (for example,
the output includes SystemTime, which may now be incorrect).

Assuming that under normal circumstances, requests will still
happen fast enough to not be shared, this may not be a problem,
but we could decide to update specific fields to not be shared.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
This commit is contained in:
Sebastiaan van Stijn 2023-06-29 17:49:09 +02:00
parent 20364bd658
commit a1c9a686b0
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GPG key ID: 76698F39D527CE8C
2 changed files with 37 additions and 27 deletions
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7
api/server/router/system/system.go
View file

@ -2,7 +2,9 @@ package system // import "github.com/docker/docker/api/server/router/system"
import (
"github.com/docker/docker/api/server/router"
"github.com/docker/docker/api/types"
buildkit "github.com/docker/docker/builder/builder-next"
"resenje.org/singleflight"
)
// systemRouter provides information about the Docker system overall.
@ -13,6 +15,11 @@ type systemRouter struct {
routes []router.Route
builder *buildkit.Builder
features func() map[string]bool
// collectSystemInfo is a single-flight for the /info endpoint,
// unique per API version (as different API versions may return
// a different API response).
collectSystemInfo singleflight.Group[string, *types.Info]
}
// NewRouter initializes a new system router

57
api/server/router/system/system_routes.go
View file

@ -57,38 +57,41 @@ func (s *systemRouter) swarmStatus() string {
}
func (s *systemRouter) getInfo(ctx context.Context, w http.ResponseWriter, r *http.Request, vars map[string]string) error {
info := s.backend.SystemInfo()
if s.cluster != nil {
info.Swarm = s.cluster.Info()
info.Warnings = append(info.Warnings, info.Swarm.Warnings...)
}
version := httputils.VersionFromContext(ctx)
if versions.LessThan(version, "1.25") {
// TODO: handle this conversion in engine-api
kvSecOpts, err := types.DecodeSecurityOptions(info.SecurityOptions)
if err != nil {
info.Warnings = append(info.Warnings, err.Error())
info, _, _ := s.collectSystemInfo.Do(ctx, version, func(ctx context.Context) (*types.Info, error) {
info := s.backend.SystemInfo()
if s.cluster != nil {
info.Swarm = s.cluster.Info()
info.Warnings = append(info.Warnings, info.Swarm.Warnings...)
}
var nameOnly []string
for _, so := range kvSecOpts {
nameOnly = append(nameOnly, so.Name)
if versions.LessThan(version, "1.25") {
// TODO: handle this conversion in engine-api
kvSecOpts, err := types.DecodeSecurityOptions(info.SecurityOptions)
if err != nil {
info.Warnings = append(info.Warnings, err.Error())
}
var nameOnly []string
for _, so := range kvSecOpts {
nameOnly = append(nameOnly, so.Name)
}
info.SecurityOptions = nameOnly
info.ExecutionDriver = "<not supported>" //nolint:staticcheck // ignore SA1019 (ExecutionDriver is deprecated)
}
info.SecurityOptions = nameOnly
info.ExecutionDriver = "<not supported>" //nolint:staticcheck // ignore SA1019 (ExecutionDriver is deprecated)
}
if versions.LessThan(version, "1.39") {
if info.KernelVersion == "" {
info.KernelVersion = "<unknown>"
if versions.LessThan(version, "1.39") {
if info.KernelVersion == "" {
info.KernelVersion = "<unknown>"
}
if info.OperatingSystem == "" {
info.OperatingSystem = "<unknown>"
}
}
if info.OperatingSystem == "" {
info.OperatingSystem = "<unknown>"
if versions.GreaterThanOrEqualTo(version, "1.42") {
info.KernelMemory = false
}
}
if versions.GreaterThanOrEqualTo(version, "1.42") {
info.KernelMemory = false
}
return info, nil
})
return httputils.WriteJSON(w, http.StatusOK, info)
}