feat: add common kubernetes readiness checks

README.md

@@ -339,6 +339,33 @@ env := testing.NewEnvironmentBuilder().
 env.ShouldReconcile(testing.RequestFromStrings("testresource"))
 ```
 
+### Readiness Checks
+
+The `pkg/readiness` package provides a simple way to check if a kubernetes resource is ready.
+The meaning of readiness depends on the resource type.
+
+#### Example
+
+```go
+deployment := &appsv1.Deployment{}
+err := r.Client.Get(ctx, types.NamespacedName{
+  Name:      "my-deployment",
+  Namespace: "my-namespace",
+}, deployment)
+
+if err != nil {
+  return err
+}
+
+readiness := readiness.CheckDeployment(deployment)
+
+if readiness.IsReady() {
+  fmt.Println("Deployment is ready")
+} else {
+  fmt.Printf("Deployment is not ready: %s\n", readiness.Message())
+}
+```
+
 ### Kubernetes resource management
 
 The `pkg/resource` package contains some useful functions for working with Kubernetes resources. The `Mutator` interface can be used to modify resources in a generic way. It is used by the `Mutate` function, which takes a resource and a mutator and applies the mutator to the resource.
@@ -412,7 +439,6 @@ func ReconcileResources(ctx context.Context, client client.Client) error {
 
 	return nil
 }
-
 ```
 
 ## Support, Feedback, Contributing

go.mod

@@ -19,6 +19,7 @@ require (
 	k8s.io/client-go v0.33.0
 	k8s.io/utils v0.0.0-20250502105355-0f33e8f1c979
 	sigs.k8s.io/controller-runtime v0.20.4
+	sigs.k8s.io/gateway-api v1.3.0
 	sigs.k8s.io/yaml v1.4.0
 )
 
@@ -66,13 +67,13 @@ require (
 	golang.org/x/time v0.10.0 // indirect
 	golang.org/x/tools v0.33.0 // indirect
 	gomodules.xyz/jsonpatch/v2 v2.4.0 // indirect
-	google.golang.org/protobuf v1.36.5 // indirect
+	google.golang.org/protobuf v1.36.6 // indirect
 	gopkg.in/evanphx/json-patch.v4 v4.12.0 // indirect
 	gopkg.in/inf.v0 v0.9.1 // indirect
 	gopkg.in/tomb.v1 v1.0.0-20141024135613-dd632973f1e7 // indirect
 	k8s.io/klog/v2 v2.130.1 // indirect
 	k8s.io/kube-openapi v0.0.0-20250318190949-c8a335a9a2ff // indirect
 	sigs.k8s.io/json v0.0.0-20241014173422-cfa47c3a1cc8 // indirect
 	sigs.k8s.io/randfill v1.0.0 // indirect
-	sigs.k8s.io/structured-merge-diff/v4 v4.6.0 // indirect
+	sigs.k8s.io/structured-merge-diff/v4 v4.7.0 // indirect
 )

go.sum

@@ -193,8 +193,8 @@ google.golang.org/protobuf v0.0.0-20200228230310-ab0ca4ff8a60/go.mod h1:cfTl7dwQ
 google.golang.org/protobuf v1.20.1-0.20200309200217-e05f789c0967/go.mod h1:A+miEFZTKqfCUM6K7xSMQL9OKL/b6hQv+e19PK+JZNE=
 google.golang.org/protobuf v1.21.0/go.mod h1:47Nbq4nVaFHyn7ilMalzfO3qCViNmqZ2kzikPIcrTAo=
 google.golang.org/protobuf v1.23.0/go.mod h1:EGpADcykh3NcUnDUJcl1+ZksZNG86OlYog2l/sGQquU=
-google.golang.org/protobuf v1.36.5 h1:tPhr+woSbjfYvY6/GPufUoYizxw1cF/yFoxJ2fmpwlM=
-google.golang.org/protobuf v1.36.5/go.mod h1:9fA7Ob0pmnwhb644+1+CVWFRbNajQ6iRojtC/QF5bRE=
+google.golang.org/protobuf v1.36.6 h1:z1NpPI8ku2WgiWnf+t9wTPsn6eP1L7ksHUlkfLvd9xY=
+google.golang.org/protobuf v1.36.6/go.mod h1:jduwjTPXsFjZGTmRluh+L6NjiWu7pchiJ2/5YcXBHnY=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c h1:Hei/4ADfdWqJk1ZMxUNpqntNwaWcugrBjAiHlqqRiVk=
 gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c/go.mod h1:JHkPIbrfpd72SG/EVd6muEfDQjcINNoR0C8j2r3qZ4Q=
@@ -226,12 +226,14 @@ k8s.io/utils v0.0.0-20250502105355-0f33e8f1c979 h1:jgJW5IePPXLGB8e/1wvd0Ich9QE97
 k8s.io/utils v0.0.0-20250502105355-0f33e8f1c979/go.mod h1:OLgZIPagt7ERELqWJFomSt595RzquPNLL48iOWgYOg0=
 sigs.k8s.io/controller-runtime v0.20.4 h1:X3c+Odnxz+iPTRobG4tp092+CvBU9UK0t/bRf+n0DGU=
 sigs.k8s.io/controller-runtime v0.20.4/go.mod h1:xg2XB0K5ShQzAgsoujxuKN4LNXR2LfwwHsPj7Iaw+XY=
+sigs.k8s.io/gateway-api v1.3.0 h1:q6okN+/UKDATola4JY7zXzx40WO4VISk7i9DIfOvr9M=
+sigs.k8s.io/gateway-api v1.3.0/go.mod h1:d8NV8nJbaRbEKem+5IuxkL8gJGOZ+FJ+NvOIltV8gDk=
 sigs.k8s.io/json v0.0.0-20241014173422-cfa47c3a1cc8 h1:gBQPwqORJ8d8/YNZWEjoZs7npUVDpVXUUOFfW6CgAqE=
 sigs.k8s.io/json v0.0.0-20241014173422-cfa47c3a1cc8/go.mod h1:mdzfpAEoE6DHQEN0uh9ZbOCuHbLK5wOm7dK4ctXE9Tg=
 sigs.k8s.io/randfill v0.0.0-20250304075658-069ef1bbf016/go.mod h1:XeLlZ/jmk4i1HRopwe7/aU3H5n1zNUcX6TM94b3QxOY=
 sigs.k8s.io/randfill v1.0.0 h1:JfjMILfT8A6RbawdsK2JXGBR5AQVfd+9TbzrlneTyrU=
 sigs.k8s.io/randfill v1.0.0/go.mod h1:XeLlZ/jmk4i1HRopwe7/aU3H5n1zNUcX6TM94b3QxOY=
-sigs.k8s.io/structured-merge-diff/v4 v4.6.0 h1:IUA9nvMmnKWcj5jl84xn+T5MnlZKThmUW1TdblaLVAc=
-sigs.k8s.io/structured-merge-diff/v4 v4.6.0/go.mod h1:dDy58f92j70zLsuZVuUX5Wp9vtxXpaZnkPGWeqDfCps=
+sigs.k8s.io/structured-merge-diff/v4 v4.7.0 h1:qPeWmscJcXP0snki5IYF79Z8xrl8ETFxgMd7wez1XkI=
+sigs.k8s.io/structured-merge-diff/v4 v4.7.0/go.mod h1:dDy58f92j70zLsuZVuUX5Wp9vtxXpaZnkPGWeqDfCps=
 sigs.k8s.io/yaml v1.4.0 h1:Mk1wCc2gy/F0THH0TAp1QYyJNzRm2KCLy3o5ASXVI5E=
 sigs.k8s.io/yaml v1.4.0/go.mod h1:Ejl7/uTz7PSA4eKMyQCUTnhZYNmLIl+5c2lQPGR2BPY=

pkg/readiness/readinesscheck.go

@@ -0,0 +1,101 @@
+package readiness
+
+import (
+	"fmt"
+	"slices"
+	"strings"
+
+	appsv1 "k8s.io/api/apps/v1"
+	batchv1 "k8s.io/api/batch/v1"
+	networkingv1 "k8s.io/api/networking/v1"
+	gatewayv1 "sigs.k8s.io/gateway-api/apis/v1"
+)
+
+type CheckResult []string
+
+func (r CheckResult) IsReady() bool {
+	return len(r) == 0
+}
+
+func (r CheckResult) Message() string {
+	return strings.Join(r, ", ")
+}
+
+func NewReadyResult() CheckResult {
+	return CheckResult{}
+}
+
+func NewNotReadyResult(message string) CheckResult {
+	return CheckResult{message}
+}
+
+func NewFailedResult(err error) CheckResult {
+	return NewNotReadyResult(fmt.Sprintf("readiness check failed: %v", err))
+}
+
+func Aggregate(results ...CheckResult) CheckResult {
+	return slices.Concat(results...)
+}
+
+// CheckDeployment checks the readiness of a deployment.
+func CheckDeployment(dp *appsv1.Deployment) CheckResult {
+	if dp.Status.ObservedGeneration < dp.Generation {
+		return NewNotReadyResult(fmt.Sprintf("deployment %s/%s not ready: observed generation outdated", dp.Namespace, dp.Name))
+	}
+
+	var specReplicas int32 = 0
+	if dp.Spec.Replicas != nil {
+		specReplicas = *dp.Spec.Replicas
+	}
+
+	if dp.Generation != dp.Status.ObservedGeneration ||
+		specReplicas != dp.Status.Replicas ||
+		specReplicas != dp.Status.UpdatedReplicas ||
+		specReplicas != dp.Status.AvailableReplicas {
+		return NewNotReadyResult(fmt.Sprintf("deployment %s/%s is not ready", dp.Namespace, dp.Name))
+	}
+
+	return NewReadyResult()
+}
+
+// CheckJob checks the completion status of a Kubernetes Job.
+func CheckJob(job *batchv1.Job) CheckResult {
+	for _, condition := range job.Status.Conditions {
+		if condition.Type == batchv1.JobComplete && condition.Status == "True" {
+			return NewReadyResult()
+		}
+		if condition.Type == batchv1.JobFailed && condition.Status == "True" {
+			return NewNotReadyResult(fmt.Sprintf("job %s/%s failed: %s", job.Namespace, job.Name, condition.Message))
+		}
+	}
+
+	return NewNotReadyResult(fmt.Sprintf("job %s/%s is not completed", job.Namespace, job.Name))
+}
+
+// CheckJobFailed checks if a Kubernetes Job has failed.
+func CheckJobFailed(job *batchv1.Job) bool {
+	for _, condition := range job.Status.Conditions {
+		if condition.Type == batchv1.JobFailed && condition.Status == "True" {
+			return true
+		}
+	}
+	return false
+}
+
+// CheckIngress checks the readiness of a Kubernetes Ingress.
+func CheckIngress(ingress *networkingv1.Ingress) CheckResult {
+	if len(ingress.Status.LoadBalancer.Ingress) > 0 {
+		return NewReadyResult()
+	}
+	return NewNotReadyResult(fmt.Sprintf("ingress %s/%s is not ready: no load balancer ingress entries", ingress.Namespace, ingress.Name))
+}
+
+// CheckGateway checks the readiness of a Kubernetes Gateway.
+func CheckGateway(gateway *gatewayv1.Gateway) CheckResult {
+	for _, condition := range gateway.Status.Conditions {
+		if condition.Type == string(gatewayv1.GatewayConditionReady) && condition.Status == "True" {
+			return NewReadyResult()
+		}
+	}
+	return NewNotReadyResult(fmt.Sprintf("gateway %s/%s is not ready: no ready condition with status True", gateway.Namespace, gateway.Name))
+}