Add option to configure tolerations in kubernetes backend (#2249)

This code add a feature to support tolerations in Kubernetes Backend

---------

Signed-off-by: Kleber Rocha <klinux@gmail.com>

docs/docs/30-administration/22-backends/40-kubernetes.md

@@ -84,6 +84,11 @@ Specify the label which is used to select the node where the job should be execu
 By default the pod will use "kubernetes.io/arch" inferred from top-level "platform" setting which is deducted from the agents' environment variable CI_SYSTEM_PLATFORM. To overwrite this, you need to specify this label in the nodeSelector section.
 See the [kubernetes documentation](https://kubernetes.io/docs/concepts/scheduling-eviction/assign-pod-node/#nodeselector) for more information on using nodeSelector.
 
+### tolerations
+
+When you use nodeSelector and the node pool is configured with Taints, you need to specify the Tolerations. Tolerations allow the scheduler to schedule pods with matching taints.
+See the [kubernetes documentation](https://kubernetes.io/docs/concepts/scheduling-eviction/taint-and-toleration/) for more information on using tolerations.
+
 Example pipeline configuration:
 
 ```yaml
@@ -105,6 +110,12 @@ steps:
             memory: 256Mi
         nodeSelector:
           beta.kubernetes.io/instance-type: p3.8xlarge
+        tolerations:
+        - key: "key1"
+          operator: "Equal"
+          value: "value1"
+          effect: "NoSchedule"
+          tolerationSeconds: 3600
 ```
 
 ### Volumes

pipeline/backend/kubernetes/pod.go

@@ -125,6 +125,22 @@ func Pod(namespace string, step *types.Step, labels, annotations map[string]stri
 		}
 	}
 
+	var tolerations []v1.Toleration
+	beTolerations := step.BackendOptions.Kubernetes.Tolerations
+	if len(beTolerations) > 0 {
+		for _, t := range step.BackendOptions.Kubernetes.Tolerations {
+			toleration := v1.Toleration{
+				Key:               t.Key,
+				Operator:          v1.TolerationOperator(t.Operator),
+				Value:             t.Value,
+				Effect:            v1.TaintEffect(t.Effect),
+				TolerationSeconds: t.TolerationSeconds,
+			}
+			tolerations = append(tolerations, toleration)
+		}
+		log.Trace().Msgf("Tolerations that will be used in the backend options: %v", beTolerations)
+	}
+
 	pod := &v1.Pod{
 		ObjectMeta: metav1.ObjectMeta{
 			Name:        podName,
@@ -136,6 +152,7 @@ func Pod(namespace string, step *types.Step, labels, annotations map[string]stri
 			RestartPolicy:      v1.RestartPolicyNever,
 			HostAliases:        hostAliases,
 			NodeSelector:       nodeSelector,
+			Tolerations:        tolerations,
 			ServiceAccountName: serviceAccountName,
 			Containers: []v1.Container{{
 				Name:            podName,

pipeline/backend/types/backend_kubernetes.go

@@ -19,6 +19,7 @@ type KubernetesBackendOptions struct {
 	Resources          Resources         `json:"resouces,omitempty"`
 	ServiceAccountName string            `json:"serviceAccountName,omitempty"`
 	NodeSelector       map[string]string `json:"nodeSelector,omitempty"`
+	Tolerations        []Toleration      `json:"tolerations,omitempty"`
 }
 
 // Resources defines two maps for kubernetes resource definitions
@@ -26,3 +27,27 @@ type Resources struct {
 	Requests map[string]string `json:"requests,omitempty"`
 	Limits   map[string]string `json:"limits,omitempty"`
 }
+
+// Defines Kubernetes toleration
+type Toleration struct {
+	Key               string             `json:"key,omitempty"`
+	Operator          TolerationOperator `json:"operator,omitempty"`
+	Value             string             `json:"value,omitempty"`
+	Effect            TaintEffect        `json:"effect,omitempty"`
+	TolerationSeconds *int64             `json:"tolerationSeconds,omitempty"`
+}
+
+type TaintEffect string
+
+const (
+	TaintEffectNoSchedule       TaintEffect = "NoSchedule"
+	TaintEffectPreferNoSchedule TaintEffect = "PreferNoSchedule"
+	TaintEffectNoExecute        TaintEffect = "NoExecute"
+)
+
+type TolerationOperator string
+
+const (
+	TolerationOpExists TolerationOperator = "Exists"
+	TolerationOpEqual  TolerationOperator = "Equal"
+)

pipeline/frontend/yaml/compiler/convert.go

@@ -116,6 +116,17 @@ func (c *Compiler) createProcess(name string, container *yaml_types.Container, s
 		}
 	}
 
+	var tolerations []backend_types.Toleration
+	for _, t := range container.BackendOptions.Kubernetes.Tolerations {
+		tolerations = append(tolerations, backend_types.Toleration{
+			Key:               t.Key,
+			Operator:          backend_types.TolerationOperator(t.Operator),
+			Value:             t.Value,
+			Effect:            backend_types.TaintEffect(t.Effect),
+			TolerationSeconds: t.TolerationSeconds,
+		})
+	}
+
 	// Kubernetes advanced settings
 	backendOptions := backend_types.BackendOptions{
 		Kubernetes: backend_types.KubernetesBackendOptions{
@@ -125,6 +136,7 @@ func (c *Compiler) createProcess(name string, container *yaml_types.Container, s
 			},
 			ServiceAccountName: container.BackendOptions.Kubernetes.ServiceAccountName,
 			NodeSelector:       container.BackendOptions.Kubernetes.NodeSelector,
+			Tolerations:        tolerations,
 		},
 	}
 

pipeline/frontend/yaml/types/backend_options.go

@@ -23,9 +23,33 @@ type KubernetesBackendOptions struct {
 	Resources          Resources         `yaml:"resources,omitempty"`
 	ServiceAccountName string            `yaml:"serviceAccountName,omitempty"`
 	NodeSelector       map[string]string `yaml:"nodeSelector,omitempty"`
+	Tolerations        []Toleration      `yaml:"tolerations,omitempty"`
 }
 
 type Resources struct {
 	Requests map[string]string `yaml:"requests,omitempty"`
 	Limits   map[string]string `yaml:"limits,omitempty"`
 }
+
+type Toleration struct {
+	Key               string             `yaml:"key,omitempty"`
+	Operator          TolerationOperator `yaml:"operator,omitempty"`
+	Value             string             `yaml:"value,omitempty"`
+	Effect            TaintEffect        `yaml:"effect,omitempty"`
+	TolerationSeconds *int64             `yaml:"tolerationSeconds,omitempty"`
+}
+
+type TaintEffect string
+
+const (
+	TaintEffectNoSchedule       TaintEffect = "NoSchedule"
+	TaintEffectPreferNoSchedule TaintEffect = "PreferNoSchedule"
+	TaintEffectNoExecute        TaintEffect = "NoExecute"
+)
+
+type TolerationOperator string
+
+const (
+	TolerationOpExists TolerationOperator = "Exists"
+	TolerationOpEqual  TolerationOperator = "Equal"
+)