@@ -32,65 +32,6 @@ Kubernetes project in 2014. Kubernetes combines
3232[ over 15 years of Google's experience] ( /blog/2015/04/borg-predecessor-to-kubernetes/ ) running
3333production workloads at scale with best-of-breed ideas and practices from the community.
3434
35- ## Going back in time
36-
37- Let's take a look at why Kubernetes is so useful by going back in time.
38-
39- ![ Deployment evolution] ( /images/docs/Container_Evolution.svg )
40-
41- ** Traditional deployment era:**
42- Early on, organizations ran applications on physical servers. There was no way to define
43- resource boundaries for applications in a physical server, and this caused resource
44- allocation issues. For example, if multiple applications run on a physical server, there
45- can be instances where one application would take up most of the resources, and as a result,
46- the other applications would underperform. A solution for this would be to run each application
47- on a different physical server. But this did not scale as resources were underutilized, and it
48- was expensive for organizations to maintain many physical servers.
49-
50- ** Virtualized deployment era:** As a solution, virtualization was introduced. It allows you
51- to run multiple Virtual Machines (VMs) on a single physical server's CPU. Virtualization
52- allows applications to be isolated between VMs and provides a level of security as the
53- information of one application cannot be freely accessed by another application.
54-
55- Virtualization allows better utilization of resources in a physical server and allows
56- better scalability because an application can be added or updated easily, reduces
57- hardware costs, and much more. With virtualization you can present a set of physical
58- resources as a cluster of disposable virtual machines.
59-
60- Each VM is a full machine running all the components, including its own operating
61- system, on top of the virtualized hardware.
62-
63- ** Container deployment era:** Containers are similar to VMs, but they have relaxed
64- isolation properties to share the Operating System (OS) among the applications.
65- Therefore, containers are considered lightweight. Similar to a VM, a container
66- has its own filesystem, share of CPU, memory, process space, and more. As they
67- are decoupled from the underlying infrastructure, they are portable across clouds
68- and OS distributions.
69-
70- Containers have become popular because they provide extra benefits, such as:
71-
72- * Agile application creation and deployment: increased ease and efficiency of
73- container image creation compared to VM image use.
74- * Continuous development, integration, and deployment: provides for reliable
75- and frequent container image build and deployment with quick and efficient
76- rollbacks (due to image immutability).
77- * Dev and Ops separation of concerns: create application container images at
78- build/release time rather than deployment time, thereby decoupling
79- applications from infrastructure.
80- * Observability: not only surfaces OS-level information and metrics, but also
81- application health and other signals.
82- * Environmental consistency across development, testing, and production: runs
83- the same on a laptop as it does in the cloud.
84- * Cloud and OS distribution portability: runs on Ubuntu, RHEL, CoreOS, on-premises,
85- on major public clouds, and anywhere else.
86- * Application-centric management: raises the level of abstraction from running an
87- OS on virtual hardware to running an application on an OS using logical resources.
88- * Loosely coupled, distributed, elastic, liberated micro-services: applications are
89- broken into smaller, independent pieces and can be deployed and managed dynamically –
90- not a monolithic stack running on one big single-purpose machine.
91- * Resource isolation: predictable application performance.
92- * Resource utilization: high efficiency and density.
93-
9435## Why you need Kubernetes and what it can do {#why-you-need-kubernetes-and-what-can-it-do}
9536
9637Containers are a good way to bundle and run your applications. In a production
@@ -174,6 +115,71 @@ Kubernetes:
174115 It shouldn't matter how you get from A to C. Centralized control is also not required. This
175116 results in a system that is easier to use and more powerful, robust, resilient, and extensible.
176117
118+ ## Historical context for Kubernetes {#going-back-in-time}
119+
120+ Let's take a look at why Kubernetes is so useful by going back in time.
121+
122+ ![ Deployment evolution] ( /images/docs/Container_Evolution.svg )
123+
124+ ** Traditional deployment era:**
125+
126+ Early on, organizations ran applications on physical servers. There was no way to define
127+ resource boundaries for applications in a physical server, and this caused resource
128+ allocation issues. For example, if multiple applications run on a physical server, there
129+ can be instances where one application would take up most of the resources, and as a result,
130+ the other applications would underperform. A solution for this would be to run each application
131+ on a different physical server. But this did not scale as resources were underutilized, and it
132+ was expensive for organizations to maintain many physical servers.
133+
134+ ** Virtualized deployment era:**
135+
136+ As a solution, virtualization was introduced. It allows you
137+ to run multiple Virtual Machines (VMs) on a single physical server's CPU. Virtualization
138+ allows applications to be isolated between VMs and provides a level of security as the
139+ information of one application cannot be freely accessed by another application.
140+
141+ Virtualization allows better utilization of resources in a physical server and allows
142+ better scalability because an application can be added or updated easily, reduces
143+ hardware costs, and much more. With virtualization you can present a set of physical
144+ resources as a cluster of disposable virtual machines.
145+
146+ Each VM is a full machine running all the components, including its own operating
147+ system, on top of the virtualized hardware.
148+
149+ ** Container deployment era:**
150+
151+ Containers are similar to VMs, but they have relaxed
152+ isolation properties to share the Operating System (OS) among the applications.
153+ Therefore, containers are considered lightweight. Similar to a VM, a container
154+ has its own filesystem, share of CPU, memory, process space, and more. As they
155+ are decoupled from the underlying infrastructure, they are portable across clouds
156+ and OS distributions.
157+
158+ Containers have become popular because they provide extra benefits, such as:
159+
160+ * Agile application creation and deployment: increased ease and efficiency of
161+ container image creation compared to VM image use.
162+ * Continuous development, integration, and deployment: provides for reliable
163+ and frequent container image build and deployment with quick and efficient
164+ rollbacks (due to image immutability).
165+ * Dev and Ops separation of concerns: create application container images at
166+ build/release time rather than deployment time, thereby decoupling
167+ applications from infrastructure.
168+ * Observability: not only surfaces OS-level information and metrics, but also
169+ application health and other signals.
170+ * Environmental consistency across development, testing, and production: runs
171+ the same on a laptop as it does in the cloud.
172+ * Cloud and OS distribution portability: runs on Ubuntu, RHEL, CoreOS, on-premises,
173+ on major public clouds, and anywhere else.
174+ * Application-centric management: raises the level of abstraction from running an
175+ OS on virtual hardware to running an application on an OS using logical resources.
176+ * Loosely coupled, distributed, elastic, liberated micro-services: applications are
177+ broken into smaller, independent pieces and can be deployed and managed dynamically –
178+ not a monolithic stack running on one big single-purpose machine.
179+ * Resource isolation: predictable application performance.
180+ * Resource utilization: high efficiency and density.
181+
182+
177183## {{% heading "whatsnext" %}}
178184
179185* Take a look at the [ Kubernetes Components] ( /docs/concepts/overview/components/ )
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