docker info: silence unhandleable warnings

AkihiroSuda · AkihiroSuda · commit 8086443a449a · 2021-01-19T15:10:21.000+09:00
The following warnings in `docker info` are now discarded,
because there is no action user can actually take.

On cgroup v1:
- "WARNING: No blkio weight support"
- "WARNING: No blkio weight_device support"

On cgroup v2:
- "WARNING: No kernel memory TCP limit support"
- "WARNING: No oom kill disable support"

`docker run` still prints warnings when the missing feature is being attempted to use.

Signed-off-by: Akihiro Suda &lt;akihiro.suda.cz@hco.ntt.co.jp&gt;
diff --git a/daemon/info_unix.go b/daemon/info_unix.go
@@ -100,10 +100,14 @@ func (daemon *Daemon) fillPlatformInfo(v *types.Info, sysInfo *sysinfo.SysInfo)
 		if !v.SwapLimit {
 			v.Warnings = append(v.Warnings, "WARNING: No swap limit support")
 		}
-		if !v.KernelMemoryTCP {
+		if !v.KernelMemoryTCP && v.CgroupVersion == "1" {
+			// kernel memory is not available for cgroup v2.
+			// Warning is not printed on cgroup v2, because there is no action user can take.
 			v.Warnings = append(v.Warnings, "WARNING: No kernel memory TCP limit support")
 		}
-		if !v.OomKillDisable {
+		if !v.OomKillDisable && v.CgroupVersion == "1" {
+			// oom kill disable is not available for cgroup v2.
+			// Warning is not printed on cgroup v2, because there is no action user can take.
 			v.Warnings = append(v.Warnings, "WARNING: No oom kill disable support")
 		}
 		if !v.CPUCfsQuota {
@@ -122,10 +126,13 @@ func (daemon *Daemon) fillPlatformInfo(v *types.Info, sysInfo *sysinfo.SysInfo)
 			v.Warnings = append(v.Warnings, "WARNING: Support for cgroup v2 is experimental")
 		}
 		// TODO add fields for these options in types.Info
-		if !sysInfo.BlkioWeight {
+		if !sysInfo.BlkioWeight && v.CgroupVersion == "2" {
+			// blkio weight is not available on cgroup v1 since kernel 5.0.
+			// Warning is not printed on cgroup v1, because there is no action user can take.
+			// On cgroup v2, blkio weight is implemented using io.weight
 			v.Warnings = append(v.Warnings, "WARNING: No blkio weight support")
 		}
-		if !sysInfo.BlkioWeightDevice {
+		if !sysInfo.BlkioWeightDevice && v.CgroupVersion == "2" {
 			v.Warnings = append(v.Warnings, "WARNING: No blkio weight_device support")
 		}
 		if !sysInfo.BlkioReadBpsDevice {

Original file line number	Diff line number	Diff line change
`@@ -100,10 +100,14 @@ func (daemon Daemon) fillPlatformInfo(v types.Info, sysInfo *sysinfo.SysInfo)`
`100`	`100`	`if !v.SwapLimit {`
`101`	`101`	`v.Warnings = append(v.Warnings, "WARNING: No swap limit support")`
`102`	`102`	`}`
`103`		`- if !v.KernelMemoryTCP {`
	`103`	`+ if !v.KernelMemoryTCP && v.CgroupVersion == "1" {`
	`104`	`+ // kernel memory is not available for cgroup v2.`
	`105`	`+ // Warning is not printed on cgroup v2, because there is no action user can take.`
`104`	`106`	`v.Warnings = append(v.Warnings, "WARNING: No kernel memory TCP limit support")`
`105`	`107`	`}`
`106`		`- if !v.OomKillDisable {`
	`108`	`+ if !v.OomKillDisable && v.CgroupVersion == "1" {`
	`109`	`+ // oom kill disable is not available for cgroup v2.`
	`110`	`+ // Warning is not printed on cgroup v2, because there is no action user can take.`
`107`	`111`	`v.Warnings = append(v.Warnings, "WARNING: No oom kill disable support")`
`108`	`112`	`}`
`109`	`113`	`if !v.CPUCfsQuota {`
`@@ -122,10 +126,13 @@ func (daemon Daemon) fillPlatformInfo(v types.Info, sysInfo *sysinfo.SysInfo)`
`122`	`126`	`v.Warnings = append(v.Warnings, "WARNING: Support for cgroup v2 is experimental")`
`123`	`127`	`}`
`124`	`128`	`// TODO add fields for these options in types.Info`
`125`		`- if !sysInfo.BlkioWeight {`
	`129`	`+ if !sysInfo.BlkioWeight && v.CgroupVersion == "2" {`
	`130`	`+ // blkio weight is not available on cgroup v1 since kernel 5.0.`
	`131`	`+ // Warning is not printed on cgroup v1, because there is no action user can take.`
	`132`	`+ // On cgroup v2, blkio weight is implemented using io.weight`
`126`	`133`	`v.Warnings = append(v.Warnings, "WARNING: No blkio weight support")`
`127`	`134`	`}`
`128`		`- if !sysInfo.BlkioWeightDevice {`
	`135`	`+ if !sysInfo.BlkioWeightDevice && v.CgroupVersion == "2" {`
`129`	`136`	`v.Warnings = append(v.Warnings, "WARNING: No blkio weight_device support")`
`130`	`137`	`}`
`131`	`138`	`if !sysInfo.BlkioReadBpsDevice {`