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Disallow PriorityClass names with 'system-' prefix for user defined priority classes #59382

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merged 2 commits into from
Feb 9, 2018
Merged

Disallow PriorityClass names with 'system-' prefix for user defined priority classes #59382

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1016d2d
Disallow PriorityClass names with 'system-' prefix for user defined p…
bsalamat Feb 6, 2018
6bad08a
Moved validation to the API side
bsalamat Feb 7, 2018
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3 changes: 3 additions & 0 deletions pkg/apis/scheduling/types.go
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Expand Up @@ -23,6 +23,9 @@ const (
// that do not specify any priority class and there is no priority class
// marked as default.
DefaultPriorityWhenNoDefaultClassExists = 0
// SystemPriorityClassPrefix is the prefix reserved for system priority class names. Other priority
// classes are not allowed to start with this prefix.
SystemPriorityClassPrefix = "system-"
)

// +genclient
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14 changes: 11 additions & 3 deletions pkg/apis/scheduling/validation/validation.go
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Expand Up @@ -17,14 +17,22 @@ limitations under the License.
package validation

import (
"strings"

"k8s.io/apimachinery/pkg/util/validation/field"
apivalidation "k8s.io/kubernetes/pkg/apis/core/validation"
"k8s.io/kubernetes/pkg/apis/scheduling"
)

// ValidatePriorityClassName can be used to check whether the given priority
// class name is valid.
var ValidatePriorityClassName = apivalidation.NameIsDNSSubdomain
// ValidatePriorityClassName checks whether the given priority class name is valid.
func ValidatePriorityClassName(name string, prefix bool) []string {
var allErrs []string
if strings.HasPrefix(name, scheduling.SystemPriorityClassPrefix) {
allErrs = append(allErrs, "priority class names with '"+scheduling.SystemPriorityClassPrefix+"' prefix are reserved for system use only")
}
allErrs = append(allErrs, apivalidation.NameIsDNSSubdomain(name, prefix)...)
return allErrs
}

// ValidatePriorityClass tests whether required fields in the PriorityClass are
// set correctly.
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4 changes: 4 additions & 0 deletions pkg/apis/scheduling/validation/validation_test.go
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Expand Up @@ -53,6 +53,10 @@ func TestValidatePriorityClass(t *testing.T) {
ObjectMeta: metav1.ObjectMeta{Name: "tier&1", Namespace: ""},
Value: 100,
},
"invalid system name": {
ObjectMeta: metav1.ObjectMeta{Name: scheduling.SystemPriorityClassPrefix + "test"},
Value: 100,
},
}

for k, v := range errorCases {
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2 changes: 2 additions & 0 deletions plugin/pkg/admission/priority/admission.go
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Expand Up @@ -44,6 +44,8 @@ const (
)

// SystemPriorityClasses defines special priority classes which are used by system critical pods that should not be preempted by workload pods.
// NOTE: In order to avoid conflict of names with user-defined priority classes, all the names must
// start with scheduling.SystemPriorityClassPrefix which is by default "system-".
var SystemPriorityClasses = map[string]int32{
"system-cluster-critical": SystemCriticalPriority,
"system-node-critical": SystemCriticalPriority + 1000,
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Should we manage the magic numbers like 1000? At least we should indicate why it is 1000.
WDYT, Bobby?

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@wgliang, the exact value of priority does not have any significance, only the relative value of priority compared to other priorites matters. So, if system-node-critical value was SystemCriticalPriority + 1, it would have had the same effect as SystemCriticalPriority + 1000, but we choose to use a larger number so that we can add more priority classes between the two existing ones if there is a need in the future.

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