kubectl apply vs kubectl create? - kubernetes

When we choose between kubectl apply and kubectl create in Kubernetes, we need to know that these commands do different things in managing resources. We use kubectl apply to manage resources that already exist. It helps us make updates without causing too much trouble. On the other hand, we use kubectl create when we want to set up new resources for the first time. Understanding this difference is very important for good Kubernetes work and managing resources over time.

In this article, we will look at the main differences between kubectl apply and kubectl create. We will also see when to use each command the right way. We will talk about best ways to manage resources in Kubernetes. We will share common examples for both commands and answer questions that many people ask. This will help us understand their roles better.

kubectl apply vs kubectl create which one to use in Kubernetes?
Understanding the Differences Between kubectl apply and kubectl create in Kubernetes
When to Use kubectl apply for Kubernetes Resource Management?
When to Choose kubectl create for Initial Resource Deployment in Kubernetes?
Best Practices for Using kubectl apply and kubectl create in Kubernetes
Common Use Cases for kubectl apply vs kubectl create in Kubernetes
Frequently Asked Questions

For more information about Kubernetes, we can read articles like What is Kubernetes and How Does It Simplify Container Management? and How Do I Use kubectl to Manage My Kubernetes Resources?. These will help us learn more.

Understanding the Differences Between kubectl apply and kubectl create in Kubernetes

In Kubernetes, we use both kubectl apply and kubectl create to manage resources. But they have different tasks and act in different ways.

kubectl create: This command helps us create a resource from a file or from stdin. It does not update existing resources. If the resource is already there, this command will give us an error. We often use it for one-time resource creation.

Example:
```
kubectl create -f deployment.yaml
```
kubectl apply: This command helps us create or update a resource. If the resource is not there, kubectl apply will create it. If it is there, kubectl apply will update it based on changes in the configuration file. This command is good for ongoing configuration management.

Example:
```
kubectl apply -f deployment.yaml
```

Key Differences:

Use Case:
- kubectl create: Good for starting resource creation.
- kubectl apply: Good for both creation and updates.
Error Handling:
- kubectl create: Gives error if the resource exists.
- kubectl apply: Creates or updates the resource without error if it exists.
Declarative vs Imperative:
- kubectl create: Imperative command (one-time action).
- kubectl apply: Declarative command (managing the desired state).
Resource Configuration:
- kubectl create: Needs the full resource details.
- kubectl apply: Allows partial updates; we only need to say what changed in the configuration.
Management Style:
- kubectl create: Best for starting resources.
- kubectl apply: Best for continuous management and version control.

To manage Kubernetes resources well, we must know when to use kubectl apply and when to use kubectl create. Use kubectl create for resources that do not change much. Use kubectl apply for environments where configurations change often.

When to Use kubectl apply for Kubernetes Resource Management?

We use kubectl apply when we want to manage Kubernetes resources. This command helps us create or update resources in a clear way. It lets us keep the desired state of resources in the cluster by using configuration files.

Key Use Cases for kubectl apply:

Declarative Configuration: We should use kubectl apply when we want to manage resources by defining their desired state in YAML files. This method makes it easy to see changes over time.

apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-app
spec:
  replicas: 3
  selector:
    matchLabels:
      app: my-app
  template:
    metadata:
      labels:
        app: my-app
    spec:
      containers:
      - name: my-app-container
        image: my-app-image:latest
        ports:
        - containerPort: 80

To apply the configuration, we run:

kubectl apply -f my-app-deployment.yaml

Update Existing Resources: We can use kubectl apply to update resources that already exist. We do not need to delete and recreate them. It combines changes smartly.
Version Control Integration: If we use GitOps practices, kubectl apply helps us keep our configuration files in version control. This way, we can easily track and go back to previous changes.
Support for Patches: We can apply patches to change certain fields in existing resources without needing to redefine the whole resource.
```
kubectl patch deployment my-app -p '{"spec":{"replicas":5}}'
```
Manage Multiple Resources: We can apply many resource configurations at the same time by pointing to a folder with YAML files.
```
kubectl apply -f ./manifests/
```

Using kubectl apply helps us follow a GitOps workflow. It makes sure that the actual state of the Kubernetes cluster matches the desired state we define in our configuration files. For more understanding, check the link what is kubectl and how do I use it to manage Kubernetes?.

When to Choose kubectl create for Initial Resource Deployment in Kubernetes?

We use kubectl create in Kubernetes to make new resources from the beginning. This command is good for initial deployments. It helps us set up resources without changing what is already there. Here is when we should pick kubectl create for the first resource deployment:

Initial Setup: We should use kubectl create when we are deploying resources for the first time. This includes Pods, Deployments, or Services. This command makes sure we are creating a new instance of a resource.
Static Resources: If the resource setup is fixed and will not change much, we can use kubectl create. It directly shows the configuration we wrote.
Simpler Scenarios: In easy cases where we do not need complex updates or settings, kubectl create makes the deployment easier for us.

Example

To create a Deployment with kubectl create, we can run this command:

kubectl create deployment my-deployment --image=my-image:latest

This command makes a new Deployment called my-deployment with the Docker image we specified.

Specific Use Cases

Creating Namespaces: If we need a new namespace, we can use kubectl create namespace my-namespace.
ConfigMaps and Secrets: For making ConfigMaps or Secrets that do not need updates, we can use:

kubectl create configmap my-config --from-literal=key1=value1
kubectl create secret generic my-secret --from-literal=password=my_password

Resource Quotas: When we set up resource quotas for the first time, we can create them without thinking about existing setups.

By using kubectl create, we make sure we are starting from a clean state. This is especially good in places where we should not change current setups by mistake.

For more details on managing Kubernetes resources well, we can check this article on Kubernetes.

Best Practices for Using kubectl apply and kubectl create in Kubernetes

When we manage Kubernetes resources, using kubectl apply and kubectl create in the right way is very important. This helps us with deployment and managing configurations. Here are some best practices for these commands.

Use kubectl apply for Declarative Management:
- This is good for managing resources over time.
- It allows us to update configurations easily.
- Example:
```
kubectl apply -f deployment.yaml
```
Use kubectl create for Initial Deployments:
- This is best for creating resources that do not change often.
- It helps us avoid unplanned changes later.
- Example:
```
kubectl create -f service.yaml
```
Keep YAML Files Versioned:
- We should store our Kubernetes YAML files in version control systems like Git. This helps us track changes over time.
Leverage kubectl apply with --record:
- We can use the --record flag to track changes made to the resources. This is useful for checking and rolling back changes.
- Example:
```
kubectl apply -f deployment.yaml --record
```
Use kubectl apply for Merging Changes:
- When we apply changes, kubectl apply merges the old configuration with the new one. This is good for updating resources.
Avoid Mixing kubectl apply and kubectl create:
- We should stick to one method for a resource. This helps us prevent confusion and mistakes.
Utilize kubectl apply --dry-run for Testing:
- We can test our changes without applying them. This helps us make sure everything is correct and avoid issues.
- Example:
```
kubectl apply -f deployment.yaml --dry-run=client
```
Monitor Resource Status After Applying Changes:
- We should always check the status of resources after applying changes. This helps us confirm they are running as we expect.
- Example:
```
kubectl get deployment my-deployment
```

By following these best practices, we can manage Kubernetes resources well using kubectl apply and kubectl create. This will make our deployment process better and reduce mistakes. For more details, we can learn about essential kubectl commands that help us in managing Kubernetes.

Common Use Cases for kubectl apply vs kubectl create in Kubernetes

In Kubernetes, we need to know when to use kubectl apply and when to use kubectl create. This is important for managing resources well. Here are some common times to use each command:

Use Cases for kubectl apply:

Updating Existing Resources:
When we need to change the setup of resources we already have, we should use kubectl apply. This command helps us change resources easily.
```
kubectl apply -f deployment.yaml
```
Managing Resource Configuration as Code:
When we handle Kubernetes resources with YAML files in version control, kubectl apply makes sure that changes in the YAML are applied to the cluster. We do not have to delete and create resources again.

Resource Merging:
kubectl apply can merge changes. For example, if a deployment has a current image and we want to change it, using kubectl apply will update just that part without changing the others.

apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-app
spec:
  template:
    spec:
      containers:
      - name: my-app
        image: my-app:v2  # Updated image version

Handling Multiple Resource Types:
We can use kubectl apply to manage many types of resources in one command. This gives us a simple way to deploy and update.
```
kubectl apply -f ./manifests/
```

Use Cases for kubectl create:

Initial Resource Creation:
We use kubectl create when we are making resources for the first time. This command is easy and good for starting setups.
```
kubectl create -f service.yaml
```
Creating Single Resources:
If we are creating just one type of resource, kubectl create is faster and easier.
```
kubectl create deployment my-app --image=my-app:latest
```
When Resource Specification is Simple:
For simple resource setups that do not need complex settings or merging, kubectl create is the better choice.
```
kubectl create configmap my-config --from-literal=key1=value1
```
Debugging Resource Creation Issues:
Using kubectl create can help us find problems with resource definitions quickly. It shows errors right away if the resource cannot be created.

These examples show that kubectl apply is great for ongoing management and updates. On the other hand, kubectl create is best for first-time resource creation and simple tasks. For more information on managing Kubernetes resources, we can read what is kubectl and how do I use it to manage Kubernetes?.

Frequently Asked Questions

1. What is the difference between `kubectl apply` and `kubectl create` in Kubernetes?

We use kubectl apply for managing Kubernetes resources. It helps us update existing resources by applying changes from configuration files. On the other hand, kubectl create is for making new resources without changing the ones that are already there. Knowing this difference is important. It helps us pick the right command for our deployment needs.

2. When should I use `kubectl apply`?

We should use kubectl apply when we want to manage the current settings of our Kubernetes resources. It lets us make updates step by step and combine changes with what is already there. This is very helpful in CI/CD pipelines and when we use infrastructure as code. By using kubectl apply, we keep our resource definitions in sync with what we want.

3. Is it possible to update resources created with `kubectl create` using `kubectl apply`?

Yes, we can update resources made with kubectl create by using kubectl apply. But we need to remember that kubectl apply will change the existing settings only if the resource’s definition matches what we have in the YAML file. This shows how flexible kubectl apply is for managing Kubernetes resources over time.

4. What are some best practices for using `kubectl apply` and `kubectl create`?

Some best practices are to use kubectl apply for managing and updating resources. We should keep kubectl create for when we first deploy things. It is good to keep our YAML files neat and organized. We should also use comments in the files to make them clearer. Following these tips can help us work better with Kubernetes and manage resources more easily.

5. Can I use `kubectl apply` for all types of Kubernetes resources?

Yes, we can use kubectl apply for most Kubernetes resources. This includes Deployments, Services, ConfigMaps, and Secrets. But we should know that some resources, like persistent volume claims, might need special attention. To manage our Kubernetes environment well, we should learn the details of each resource type and how they work with kubectl apply.

For more information on Kubernetes and its parts, we can look at articles about Kubernetes key components or understanding Kubernetes networking.