The Application Containerization is something that is becoming more and more visible in the present scenario. This is mainly due to the engagement of more and more large-scale organizations in this approach. Kubernetes is a trusted platform in this matter that simply let the users keep up the pace all the time. Basically, Application Containerization is a virtualization approach that is based on the Operating System and is generally considered for the deployment as well as running the distributed applications. It is not always necessary to launch the entire VM for this task if one if handling the task through the Kubernetes. The best thing is containers can easily run on the Virtual Machines, Cloud environments, as well as in bare-metal systems. Kubernetes has a lot of concepts and terms associated with it. To get the most desired results, there is always a need to understand them in a proper manner. In this post, you will find some useful information and a true comparison of the Kubernetes Deployment vs. Kubernetes Services.
What exactly Deployments are and how they are different from Services
When it comes to managing the stateless services which generally run on the cluster, the Kubernetes deployments is something that is widely considered. The prime objective is very simple and i.e. to manage the pods which are similar. In addition to this, upgrading these pods is also done through the deployment approach. Generally, a deployment controller is responsible for offering the updates which are declarative in nature for both Replica sets as well as for the Pods. When the users describe a desired state in the object associated with the deployment, the controller is always responsible for modifying the real state to the one which is desired and this is done at a controller rate. This is pretty different as compare to that in Services. For creating a new replica sets, Deployments can easily be defined. It is also possible to move the existing deployments and control other new resources through it.
- It must be kept in mind that the Kubernetes cannot manage the replica sets which are owned by the deployment.
- The cases which are already used are necessary to be covered by simply manipulating the object within the deployment.
Related Article: Detailed Study On Kubernetes Dashboard
What is Kubernetes Services and how it is different from Deployments
The Service is generally regarded as the abstraction which is responsible for clearly defining the pods which are logical. It also defines the policy for accessing them and the same is known as a micro-service. There is no such approach or a micro-deployment available. There is a Label selector which determines the pods which services target. Service without selector is not possible. However, on the other side, Deployment doesn’t depend on any selector for accomplish the task in a reliable manner. Next major difference is Decoupling process can easily be opted in the Services and Deployments doesn’t allow the same.
- For all the native applications, there is an API which updates itself automatically when a change is seen in the pods available within a service.
- The non-native applications, the same approach depends on a virtual-IP based bridge to the Services. The same is responsible for performing tasks such as redirecting the apps.
Starting a deployment and starting a service
There is not much difference between the Deployment and the Services when it comes to starting them. However, there is a basic condition that put this process separate from one another.
- There is a condition that users handling deployments tasks have to follow. The fact is it is not possible to start the deployment without changing the Deployment pod template. There are times when the containers images or the label needs to be updated. After every such update, the deployment needs to be updated too for its triggering in the next stage.
- A service on the other hand is independent of this updating approach. It is not always necessary that to trigger a service, the Replica Set or the pods belonging to the Service for that particular task also needs to be changed.
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Kubernetes Deployment vs. Kubernetes Services- Finding the ReplicaSet Objects
Finding the ReplicaSets is something that is considered as an important task in both these approaches. Although it is not a big deal to find the same, there are a few things that matter and needs to be paid attention to for getting the outcome in the expected manner.
- In Deployments, it is necessary that the ReplicaSets can be located only if a filtering algorithm is used on the labels. This is because they are huge in number when compared to the ReplicaSets belonging to the Services.
- Generally, Services has only one label on all the sets and this makes it independent of any filtering approach.
- The same procedure of filtering is also applicable in the Pod section of the Deployment.
Pods differences- Kubernetes deployment vs. Kubernetes Services
There are Pods which are an important part of the Kubernetes Services. Pods are generally regarded as mortals and the best thing is they have a well-defined lifecycle from which it is possible to derive a lot of useful information about the concerned task that is going on. The only drawback in case of Service is Pods depends on the Nodes. When a node no longer remains available, pods also get lost automatically. On the other side, the pods are not dependent on the nodes when it comes to Kubernetes Deployments. This gives Deployments a cunning advantage over the Services.
The applications keep running in the Service environment even if the Pods no longer remain available. However, if the pods have an issue with it in case of Deployment, the applications are not always necessary to run with same features.
The key role of a Service in the Deployment task
It is quite true that there are some of the very important tasks in the Deployments that generally depend on the service section upto some extent. However, this is not true for all the projects. The one which are more complex has more dependency on each other. It is possible to deploy both the Deployments and the Services for the same tasks provided some important conditions are met.
- In service, there are several pods and each has an IP address that is unique. Even the Deployment has the IPs defined for the Pods but when it comes to exposing the IP to a location which is outside the cluster, Deployments needs Services to accomplish this task in a fruitful manner.
Receiving the traffic by the applications - Kubernetes Deployment vs. Kubernetes Services
It is quite true that applications need to deal with traffic for performing almost all the task reliably. The traffic management strategy for all the applications is not necessarily mean to be same. It can vary depending on some of the key factors. The users can easily define the traffic for the apps through different segments but it is not same for every single application.
- In Services, the applications have no restriction on them for receiving the traffic. However, there are some basic conditions on the applications in Deployments for accomplishing this task.
- Almost all the services are possible to be exposed in the different manner in any environment. The same is not applicable to the Kubernetes Deployments.
- The selector always needs to be defined in the Services while dealing with the applications while the same is optional in case of Deployments.
- For the endpoint objects, the functionality is not dependent on the labels.
Using the Deployments and their Services at the same time
For the users, it is possible to use Services as well as the Deployments at the same time for most of the task. This is possible due to one simple reason and i.e. the availability of the expose in the kubectl command. It simply enables users to create a Deployment at the same time while a Service is created.
- It is necessary to attach the labels on the both in case such a practice is followed. Labels can even be attached at a later time.
- Through labels, it is possible to modify the Services and the Deployments anytime the need of same is felt.
Managing the updates with Deployments and Services
Deployments are much superior to the Replication Controllers and they widely support the update management in a manner better than that of the Services. A wait time can also be defined in case of Deployments when it comes to managing the updates which is not yet possible with the Services. This wait time actually enable containers to have time availability to handle traffic in a reliable manner. The multiple revisions of a deployment can also be managed effectively at the same time while managing the updates. This is another good thing about Deployment when compared to Services.
So this is how the Kubernetes Services and Deployments can be related to each other. Although they seem quite similar in terms of functionality, there are several key differences that put them separate from one another. Both have their own pros and cons associated with them. The exact output of both these approaches depends largely on the type and complexity of the project one handle with them.