In Docker, containers share all host resources without formal boundaries.
In Kubernetes, resource management ensures that:
This is achieved using requests, limits, quotas, and namespaces.
Resource Units
Resource Requests and Limits
Type	Example Unit	Notes
Ephemeral Storage	`ephemeral-storage: "1Gi"`	Temporary local disk
HugePages	`hugepages-2Mi: 128Mi`	For special workloads
Custom Resources	`nvidia.com/gpu: 1`	GPU or device-specific
Every container can specify requests (minimum) and limits (maximum) for CPU and memory.

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
 resources:
  requests:
    cpu: "250m"
    memory: "256Mi"
  limits:
    cpu: "500m"
    memory: "512Mi"

<details class="details details--default" data-variant="default"><summary>Pod with Resource Requests and Limits</summary>
<p>Create a file called pod-with-resources.yaml:</p>

<div class="language-yaml highlighter-rouge"><div class="highlight"><pre class="highlight"><code><table class="rouge-table"><tbody><tr><td class="rouge-gutter gl"><pre class="lineno">1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
</pre></td><td class="rouge-code"><pre><span class="na">apiVersion</span><span class="pi">:</span> <span class="s">v1</span>
<span class="na">kind</span><span class="pi">:</span> <span class="s">Pod</span>
<span class="na">metadata</span><span class="pi">:</span>
  <span class="na">name</span><span class="pi">:</span> <span class="s">cpu-mem-demo</span>
<span class="na">spec</span><span class="pi">:</span>
  <span class="na">containers</span><span class="pi">:</span>
  <span class="pi">-</span> <span class="na">name</span><span class="pi">:</span> <span class="s">stress-container</span>
    <span class="na">image</span><span class="pi">:</span> <span class="s">polinux/stress</span>
    <span class="na">command</span><span class="pi">:</span> <span class="pi">[</span><span class="s2">"</span><span class="s">stress"</span><span class="pi">]</span>
    <span class="na">args</span><span class="pi">:</span> <span class="pi">[</span><span class="s2">"</span><span class="s">--cpu"</span><span class="pi">,</span> <span class="s2">"</span><span class="s">1"</span><span class="pi">,</span> <span class="s2">"</span><span class="s">--vm"</span><span class="pi">,</span> <span class="s2">"</span><span class="s">1"</span><span class="pi">,</span> <span class="s2">"</span><span class="s">--vm-bytes"</span><span class="pi">,</span> <span class="s2">"</span><span class="s">200M"</span><span class="pi">,</span> <span class="s2">"</span><span class="s">--vm-hang"</span><span class="pi">,</span> <span class="s2">"</span><span class="s">1"</span><span class="pi">]</span>
    <span class="na">resources</span><span class="pi">:</span>
      <span class="na">requests</span><span class="pi">:</span>
        <span class="na">cpu</span><span class="pi">:</span> <span class="s2">"</span><span class="s">250m"</span>
        <span class="na">memory</span><span class="pi">:</span> <span class="s2">"</span><span class="s">256Mi"</span>
      <span class="na">limits</span><span class="pi">:</span>
        <span class="na">cpu</span><span class="pi">:</span> <span class="s2">"</span><span class="s">500m"</span>
        <span class="na">memory</span><span class="pi">:</span> <span class="s2">"</span><span class="s">512Mi"</span>
</pre></td></tr></tbody></table></code></pre></div></div>

<p>Deploy the pod:</p>

<div class="language-bash highlighter-rouge"><div class="highlight"><pre class="highlight"><code><table class="rouge-table"><tbody><tr><td class="rouge-gutter gl"><pre class="lineno">1
2
3
4
</pre></td><td class="rouge-code"><pre>kubectl apply <span class="nt">-f</span> pod-with-resources.yaml
kubectl get pods
kubectl describe pod cpu-mem-demo
kubectl top pods
</pre></td></tr></tbody></table></code></pre></div></div>

<p>Observe how the scheduler allocates CPU shares and memory quota to this Pod.</p>

</details>
---

## Namespaces

Namespaces organize resources logically within a cluster.
They act like virtual clusters on top of a single physical cluster.

<details class="details details--default" data-variant="default"><summary>Built-in namespaces</summary>
<ul>
  <li>Run the following commands on the headnode to list all available namespaces.</li>
  <li>You can use either <code class="language-plaintext highlighter-rouge">ns</code> or <code class="language-plaintext highlighter-rouge">namespace</code>.</li>
</ul>

<div class="language-bash highlighter-rouge"><div class="highlight"><pre class="highlight"><code><table class="rouge-table"><tbody><tr><td class="rouge-gutter gl"><pre class="lineno">1
2
</pre></td><td class="rouge-code"><pre>kubectl get namespace
kubectl get ns
</pre></td></tr></tbody></table></code></pre></div></div>

<figure>
  <picture>
    <!-- Auto scaling with imagemagick -->
    <!--
      See https://www.debugbear.com/blog/responsive-images#w-descriptors-and-the-sizes-attribute and
      https://developer.mozilla.org/en-US/docs/Learn/HTML/Multimedia_and_embedding/Responsive_images for info on defining 'sizes' for responsive images
    -->
    
      
        <source class="responsive-img-srcset" srcset="/assets/img/courses/csc478/resource-management/namespaces-480.webp 480w,/assets/img/courses/csc478/resource-management/namespaces-800.webp 800w,/assets/img/courses/csc478/resource-management/namespaces-1400.webp 1400w," type="image/webp" sizes="95vw" />
      
    
    <img src="/assets/img/courses/csc478/resource-management/namespaces.png" width="50%" height="auto" data-zoomable="" loading="lazy" onerror="this.onerror=null; $('.responsive-img-srcset').remove();" />
  </picture>

  
</figure>

<ul>
  <li><code class="language-plaintext highlighter-rouge">default</code>: Default namespace for user-created resources without namespace specified.</li>
  <li><code class="language-plaintext highlighter-rouge">kube-system</code>: Special, reserved namespace for system components.</li>
  <li><code class="language-plaintext highlighter-rouge">kube-public</code>: Name space for resources meant to be readable by all users.</li>
  <li><code class="language-plaintext highlighter-rouge">kube-node-lease</code>: for Lease objects, which serves as node heartbeats.</li>
</ul>

</details>
<details class="details details--default" data-variant="default"><summary>Create a new namespace</summary>
<p>Create a file named <code class="language-plaintext highlighter-rouge">namespace.yaml</code>:</p>

<div class="language-bash highlighter-rouge"><div class="highlight"><pre class="highlight"><code><table class="rouge-table"><tbody><tr><td class="rouge-gutter gl"><pre class="lineno">1
2
3
4
5
6
</pre></td><td class="rouge-code"><pre>apiVersion: v1
kind: Namespace
metadata:
  name: team-alpha
  labels:
    environment: development
</pre></td></tr></tbody></table></code></pre></div></div>

<p>Deploy the namespace manifest and check its availability.</p>

<div class="language-bash highlighter-rouge"><div class="highlight"><pre class="highlight"><code><table class="rouge-table"><tbody><tr><td class="rouge-gutter gl"><pre class="lineno">1
2
</pre></td><td class="rouge-code"><pre>kubectl apply <span class="nt">-f</span> namespace.yaml
kubectl get namespaces
</pre></td></tr></tbody></table></code></pre></div></div>

</details>
## ResourceQuota

When multiple teams share a cluster, you can restrict total resource usage per namespace.

<details class="details details--default" data-variant="default"><summary>quote Details</summary>
<p>A resource quota, defined by a ResourceQuota object, provides constraints that limit aggregate resource consumption per namespace. A ResourceQuota can also limit the quantity of objects that can be created in a namespace by API kind, as well as the total amount of infrastructure resources that may be consumed by API objects found in that namespace.</p>

</details>
<details class="details details--default" data-variant="default"><summary>Create namespace and quota</summary>
<div class="language-bash highlighter-rouge"><div class="highlight"><pre class="highlight"><code><table class="rouge-table"><tbody><tr><td class="rouge-gutter gl"><pre class="lineno">1
</pre></td><td class="rouge-code"><pre>kubectl create namespace dev
</pre></td></tr></tbody></table></code></pre></div></div>

<p>Create a manifest file called <code class="language-plaintext highlighter-rouge">dev-quota.yaml</code>:</p>

<div class="language-yaml highlighter-rouge"><div class="highlight"><pre class="highlight"><code><table class="rouge-table"><tbody><tr><td class="rouge-gutter gl"><pre class="lineno">1
2
3
4
5
6
7
8
9
10
11
12
</pre></td><td class="rouge-code"><pre><span class="na">apiVersion</span><span class="pi">:</span> <span class="s">v1</span>
<span class="na">kind</span><span class="pi">:</span> <span class="s">ResourceQuota</span>
<span class="na">metadata</span><span class="pi">:</span>
  <span class="na">name</span><span class="pi">:</span> <span class="s">dev-quota</span>
  <span class="na">namespace</span><span class="pi">:</span> <span class="s">dev</span>
<span class="na">spec</span><span class="pi">:</span>
  <span class="na">hard</span><span class="pi">:</span>
    <span class="na">requests.cpu</span><span class="pi">:</span> <span class="s2">"</span><span class="s">2"</span>
    <span class="na">requests.memory</span><span class="pi">:</span> <span class="s">1Gi</span>
    <span class="na">limits.cpu</span><span class="pi">:</span> <span class="s2">"</span><span class="s">4"</span>
    <span class="na">limits.memory</span><span class="pi">:</span> <span class="s">1Gi</span>
    <span class="na">pods</span><span class="pi">:</span> <span class="s2">"</span><span class="s">4"</span>
</pre></td></tr></tbody></table></code></pre></div></div>

<p>Apply the manifest file:</p>

<div class="language-bash highlighter-rouge"><div class="highlight"><pre class="highlight"><code><table class="rouge-table"><tbody><tr><td class="rouge-gutter gl"><pre class="lineno">1
2
</pre></td><td class="rouge-code"><pre>kubectl apply <span class="nt">-f</span> dev-quota.yaml
kubectl describe quota dev-quota <span class="nt">-n</span> dev
</pre></td></tr></tbody></table></code></pre></div></div>

<ul>
  <li>Create and apply following deployment manifest called <code class="language-plaintext highlighter-rouge">quota-demo-deploy.yaml</code></li>
</ul>

<div class="language-yaml highlighter-rouge"><div class="highlight"><pre class="highlight"><code><table class="rouge-table"><tbody><tr><td class="rouge-gutter gl"><pre class="lineno">1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
</pre></td><td class="rouge-code"><pre><span class="na">apiVersion</span><span class="pi">:</span> <span class="s">apps/v1</span>
<span class="na">kind</span><span class="pi">:</span> <span class="s">Deployment</span>
<span class="na">metadata</span><span class="pi">:</span>
  <span class="na">name</span><span class="pi">:</span> <span class="s">quota-demo</span>
  <span class="na">namespace</span><span class="pi">:</span> <span class="s">dev</span>
<span class="na">spec</span><span class="pi">:</span>
  <span class="na">replicas</span><span class="pi">:</span> <span class="m">5</span>
  <span class="na">selector</span><span class="pi">:</span>
    <span class="na">matchLabels</span><span class="pi">:</span>
      <span class="na">app</span><span class="pi">:</span> <span class="s">quota-demo</span>
<span class="na">template</span><span class="pi">:</span>
  <span class="na">metadata</span><span class="pi">:</span>
    <span class="na">labels</span><span class="pi">:</span>
      <span class="na">app</span><span class="pi">:</span> <span class="s">quota-demo</span>
  <span class="na">spec</span><span class="pi">:</span>
    <span class="na">containers</span><span class="pi">:</span>
    <span class="pi">-</span> <span class="na">name</span><span class="pi">:</span> <span class="s">busybox-demo</span>
      <span class="na">image</span><span class="pi">:</span> <span class="s">busybox</span>
      <span class="na">command</span><span class="pi">:</span> <span class="pi">[</span><span class="s2">"</span><span class="s">sh"</span><span class="pi">,</span> <span class="s2">"</span><span class="s">-c"</span><span class="pi">,</span> <span class="s2">"</span><span class="s">while</span><span class="nv"> </span><span class="s">true;</span><span class="nv"> </span><span class="s">do</span><span class="nv"> </span><span class="s">echo</span><span class="nv"> </span><span class="s">$(date)</span><span class="nv"> </span><span class="s">&gt;&gt;</span><span class="nv"> </span><span class="s">/tmp/date.log;</span><span class="nv"> </span><span class="s">sleep</span><span class="nv"> </span><span class="s">10;</span><span class="nv"> </span><span class="s">done"</span><span class="pi">]</span>
      <span class="na">resources</span><span class="pi">:</span>
        <span class="na">requests</span><span class="pi">:</span>
          <span class="na">cpu</span><span class="pi">:</span> <span class="s2">"</span><span class="s">500m"</span>
          <span class="na">memory</span><span class="pi">:</span> <span class="s2">"</span><span class="s">256Mi"</span>
        <span class="na">limits</span><span class="pi">:</span>
          <span class="na">cpu</span><span class="pi">:</span> <span class="s2">"</span><span class="s">1"</span>
          <span class="na">memory</span><span class="pi">:</span> <span class="s2">"</span><span class="s">256Mi"</span>
</pre></td></tr></tbody></table></code></pre></div></div>

<ul>
  <li>Confirm that we are not able to go above 4 replicas, as any Pod created in the <code class="language-plaintext highlighter-rouge">dev</code> namespace will be checked against this quota.
If usage exceeds these totals, new Pods are rejected.</li>
</ul>

<div class="language-bash highlighter-rouge"><div class="highlight"><pre class="highlight"><code><table class="rouge-table"><tbody><tr><td class="rouge-gutter gl"><pre class="lineno">1
2
3
4
5
6
7
8
9
</pre></td><td class="rouge-code"><pre><span class="c"># Verify quota</span>
kubectl describe quota dev-quota <span class="nt">-n</span> dev

<span class="c"># Deploy workloads</span>
kubectl apply <span class="nt">-f</span> quota-demo-deploy.yaml

<span class="c"># Observe results</span>
kubectl get pods <span class="nt">-n</span> dev
kubectl describe deployment quota-demo <span class="nt">-n</span> dev
</pre></td></tr></tbody></table></code></pre></div></div>

<ul>
  <li>Delete the quote-demo deployment!</li>
</ul>

</details>
## LimitRange

- A `LimitRange` defines default, minimum, and maximum resources for containers within a namespace.

<details class="details details--default" data-variant="default"><summary>Default Limits</summary>
<ul>
  <li>Create a manifest file called <code class="language-plaintext highlighter-rouge">default-limits.yaml</code>:</li>
</ul>

<div class="language-yaml highlighter-rouge"><div class="highlight"><pre class="highlight"><code><table class="rouge-table"><tbody><tr><td class="rouge-gutter gl"><pre class="lineno">1
2
3
4
5
6
7
8
9
10
11
12
13
14
</pre></td><td class="rouge-code"><pre><span class="na">apiVersion</span><span class="pi">:</span> <span class="s">v1</span>
<span class="na">kind</span><span class="pi">:</span> <span class="s">LimitRange</span>
<span class="na">metadata</span><span class="pi">:</span>
  <span class="na">name</span><span class="pi">:</span> <span class="s">default-limits</span>
  <span class="na">namespace</span><span class="pi">:</span> <span class="s">dev</span>
<span class="na">spec</span><span class="pi">:</span>
  <span class="na">limits</span><span class="pi">:</span>
  <span class="pi">-</span> <span class="na">default</span><span class="pi">:</span>
      <span class="na">cpu</span><span class="pi">:</span> <span class="s">500m</span>
      <span class="na">memory</span><span class="pi">:</span> <span class="s">512Mi</span>
    <span class="na">defaultRequest</span><span class="pi">:</span>
      <span class="na">cpu</span><span class="pi">:</span> <span class="s">200m</span>
      <span class="na">memory</span><span class="pi">:</span> <span class="s">256Mi</span>
    <span class="na">type</span><span class="pi">:</span> <span class="s">Container</span>
</pre></td></tr></tbody></table></code></pre></div></div>

<ul>
  <li>Apply these limits to the <code class="language-plaintext highlighter-rouge">dev</code> namespace:</li>
</ul>

<div class="language-bash highlighter-rouge"><div class="highlight"><pre class="highlight"><code><table class="rouge-table"><tbody><tr><td class="rouge-gutter gl"><pre class="lineno">1
</pre></td><td class="rouge-code"><pre>kubectl apply <span class="nt">-f</span> default-limits.yaml
</pre></td></tr></tbody></table></code></pre></div></div>

<ul>
  <li>Now, any Pod without explicit resource requests/limits will inherit these defaults.</li>
</ul>

</details>
## How Resource Enforcement Works Internally


Layer	| Responsibility
----- | ------ 
Scheduler	| Uses requests to pick a node that can host the Pod
Kubelet	| Reserves node resources according to requests
Container | runtime (cgroups)	Enforces limits (CPU throttling or OOM kill)
Metrics server	| Reports usage (`kubectl top`)
Rancher UI / Dashboard	| Visualizes namespace-level usage

## Quality of Service (QoS) Classes

Kubernetes classifies Pods based on resource configuration:

QoS Class	 | Condition	                            | Behavior
---------- | -------------------------------------- | ---------------------------
Guaranteed |	All containers have requests = limits |	Highest priority, least likely to be evicted
Burstable	 | Requests < limits	                    | Medium priority
BestEffort | No requests or limits	                | Lowest priority, evicted first

You can check a Pod’s QoS with:

```bash
kubectl get pod cpu-mem-demo -o jsonpath='{.status.qosClass}'
Resource Units and Management in Kubernetes

Logistics

What Is Resource Management?

Resource Units

Resource Requests and Limits
