You can utilize the MilesWeb containers with the PaaS technology for migrating your VM-based Java applications inside the modern container clusters. The migration of Java applications to the portable containers is a simple process and it also includes the benefits of easy scaling and easy management within the MilesWeb PaaS environment.
Hardware virtualization is a very important step in the field of application hosting. Hypervisors enable the users to isolate multiple applications within a single hardware platform. This gives freedom to the users for using hardware resources more efficiently by hosting miscellaneous and diverse workloads within the same infrastructure. The fact is that virtual machines have huge overheads when it comes to resource consumption because every VM runs a dedicated operating system of its own.
The container technology enhances the benefits of virtualization by enabling the containers to share the OS kernel, file system, networking stack and other system resources present in the host machine. All this is done while ensuring that less memory is used and less CPU overhead is caused.
If your organization is a bit skeptical and cautious about making the transition from VM to containers, refer to the advantages of containers mentioned below:
- Enhanced and efficient resource utilization as compared to the VMs
- Easy scaling and resizing the container limits; scaling can be done on the go without the need to reboot
- Faster provisioning and faster start times for containers in comparison to the VMs
- Granular resource provisioning and ability to share resources among containers present on the same host
- Container teplates that are publically available and based on the Docker packaging standard that simplifies the process of creating new images for specific projects
MilesWeb PaaS platform offers managed containerized application platforms for many programming languages like PHP, Java, Ruby, Python, Node.js and .Net. In the beginning, this platform was designed on Virtuozzo containers and when the Docker technology came into existance, they already had a profound expertise in containerization and support for Docker standard was immediately added. The support provided for multi-cloud options enables the use of MilesWeb PaaS on various IaaS platforms as well. The container portability benefits can be maximized by the users by mixing various cloud services and managing them though the same UI or API.
MilesWeb PaaS helps the developers in terms of migrating from hypervisors to containers quickly and ensures affordability without making any changes in the application code. In order to illustrate how this transition can be enabled let’s have a look at the structure and scaling process of a VM-based application operating in a GlassFish server (Java EE application server) and how it can be transferred to the containers using the MilesWeb PaaS technology.
Starting Point : GlassFish Server In A VM
When it comes to a GlassFish based server environment, the domain administration server (DAS) is the central management platform from which all the resources and applications present in the cluster are configured and propagated to every worker instance. These workers host your web applications, web services and the other resources.
If you wish to add more resources to the same VM, you will have to move to a bigger machine and in most of the cases, this will lead to downtime during the migration process. This reduces the efficiency of the VMs when it comes to vertical scaling. Moreover, for scaling a GlassFish cluster horizontally in VMs, you will have to implement the following tasks:
- Provision a new VM that has a preconfigured GlassFish template
- Configure SSH connect and add the VM as an SSH node to the DAS (domain administration server)
- Generate a new remote worker instance on a node through the DAS UI or admin CLI
You have to repeat this process every time you reach the maximum scaling limit and need more resources. Implementation of these steps require a significant amount of time and it might lead to human errors that might create a negative impact on the whole project.
Making The Move : Decomposition To Containers
When the user wants to migrate from the VM, it is important to first decompose the monolithic application topology first in small logical pieces that are distributed between a set of interconnected containers. Every application component must be placed inside an isolated container. This method simplifies the application topology and is useful in case some specific parts of the project become unnecessary in the future architecture.
There are two types of containers that can be selected to run a project : application containers and system containers.
An application container (like a Docker) usually runs a bit more than a single process. This container is more suitable for building new projects as in this container, it is relatively easy to create images with the use of publically available Docker templates. In this container, it is also possible to meet the needs of the cloud-native approach from the initial stage.
A system container (LXD, Virtuozzo) operates more like a complete operating system. It is capable of running full-fledged init systems like Systemd, SysVinit and OpenRC that enables the processes to generate other processes like OpenSSH, Crond or Syslogd together inside a single container. This container is more preferred for the monolithic and legacy applications as it enables the user to reuse the architectures and configurations that are implemented in the original design for running in the VMs.
System containers provide multiple benefits while migrating an existing legacy application. Important attributes like hostnames, IP addresses and locally stored data is unaffected due to the container downtimes. There is no need to carry out port mapping and the users get a much better isolation along with virtualization of the resources. Additionally, the users get advantages like compatibility with SSH-based config tools, hibernation and live migration of the memory state. The only perceptible disadvantage of the system containers as compared to the application containers is that it might be a little slow in terms of the start-up time as the system containers are a bit heavier because of the additional services required for operating multiple processes.
MilesWeb makes it possible to run both application containers and system containers. Other PaaS vendors utilize the ‘Twelve-factor app methodology’; however, MilesWeb does not make it compulsory for the customers to use any specific approach or application design for deploying the cloud-native micro services and legacy monolith applications. Developers can modify their code to a proprietary API for deploying the applications to the cloud. The projects can be up and running within a few minutes with the use of an application achieve or with just a link to the project in GitHub. This simplifies the entry point and makes it more seamless. It also reduces the go-to-market times and eliminates vendor lock-in.
Destination : GlassFish Server In A Container
The elements belonging to a GlassFish server remain the same in a container as in a VM but they are spread over many isolated containers.
It is possible to add or remove the worker nodes automatically and they can also be attached to a DAS node through a container orchestration platform and a set of automation scripts that are natively integrated.
MilesWeb eases the complexity of migration and it automates the processes of scaling and clustering. Once the application starts operating in a containerized environment, the PaaS technology manages all the steps involved in the application lifecycle and it also ensures easy creation of test, dev, production environments and simplifies horizontal/vertical scaling out of the box. For instance, there is already a GlassFish cluster that is pre-configured and highly available and it is created with automatic provisioning of the replicated instances. As a result of this, there is no need for the developers to write custom scripts in order to implement the required logic and they can concentrate on coding.
The migration process from VMs to containers seems difficult but in reality it is a very straightforward process and it is accompanied with significant long term benefits. With the move to the containers, the system resource consumption will be reduced, horizontal scaling will be simplified, automatic vertical scaling will be enabled without the need of restart and infrastructure utilization will be increased by hosting various applications in a single physical server. All this can be achieved without compromising on the security aspect. The final benefit that is important for the users to know is the portability of the containers. Users have the ability to move their containers across various cloud vendors and as a result of this, your company can avoid vendor lock-in and take the advantage of the declining cloud service costs.
Use of the MilesWeb PaaS platform not just simplifies the migration process but it also simplifies the scaling and management of the containerized workloads throughout the lifecycle of the application. With the support of right automation and orchestration, the developers and IT ops teams can avail of all the benefits of the containers without any in-depth knowledge about this technology and they can focus their complete attention on their core work.