Service mesh concept overview in Kubernetes - Step-by-Step Execution

Process Flow - Service mesh concept overview

Client Pod

↓

Sidecar Proxy

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Service Mesh Control Plane

↓

Sidecar Proxy

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Server Pod

The service mesh adds sidecar proxies to pods to manage communication, controlled by a central control plane.

Execution Sample

Kubernetes

kubectl apply -f service-mesh.yaml
# Deploys service mesh components
kubectl get pods -n istio-system
# Lists mesh control plane pods
kubectl get svc -n istio-system
# Shows services managed by mesh

Deploy service mesh, check control plane pods, and view services managed by the mesh.

Process Table

Step	Action	Component	Result	Notes
1	Deploy service mesh YAML	kubectl	Control plane pods start	Control plane manages mesh config
2	Client Pod sends request	Client Pod	Request intercepted by sidecar proxy	Sidecar handles routing and security
3	Sidecar proxy consults control plane	Sidecar Proxy	Receives routing rules	Control plane enforces policies
4	Sidecar proxy forwards request	Sidecar Proxy	Request sent to server pod's sidecar	Transparent to application
5	Server pod receives request	Server Pod	Processes request normally	No code change needed
6	Response sent back same path	Sidecar Proxy	Response intercepted and logged	Observability enabled
7	Exit	N/A	Communication complete	Request lifecycle finished

💡 Request completed through sidecar proxies with control plane managing policies

Status Tracker

Variable	Start	After Step 2	After Step 4	Final
Request State	Not sent	Intercepted by client sidecar	Forwarded to server sidecar	Processed by server pod
Routing Rules	Empty	Fetched from control plane	Applied to request	N/A
Policy Enforcement	None	Checked by sidecar	Enforced on request	N/A

Key Moments - 3 Insights

Why does the client pod's request go through a sidecar proxy?

Because the sidecar proxy intercepts all pod traffic to apply routing and security rules as shown in execution_table step 2.

Does the application code in pods need to change to use a service mesh?

No, the application code stays the same; the sidecar proxies handle communication transparently as seen in step 5.

What role does the control plane play in the service mesh?

The control plane provides routing and policy rules to sidecars, managing communication centrally as in step 3.

Visual Quiz - 3 Questions

Look at the execution table, at which step does the sidecar proxy get routing rules from the control plane?

A Step 2

B Step 4

C Step 3

D Step 5

💡 Hint

Check the 'Action' and 'Result' columns in execution_table row for step 3.

According to variable_tracker, what is the state of the request after step 4?

A Forwarded to server sidecar

B Intercepted by client sidecar

C Not sent

D Processed by server pod

💡 Hint

Look at 'Request State' variable in variable_tracker after step 4.

If the control plane fails, which step in the execution_table would be directly affected?

A Step 2 - Request interception

B Step 3 - Sidecar gets routing rules

C Step 5 - Server pod processes request

D Step 6 - Response sent back

💡 Hint

Control plane provides routing rules as shown in step 3.

Concept Snapshot

Service mesh adds sidecar proxies to pods.
Sidecars intercept and manage all pod communication.
Control plane centrally manages routing and policies.
No app code changes needed.
Improves security, observability, and traffic control.

Full Transcript

A service mesh works by adding a sidecar proxy to each pod. When a client pod sends a request, the sidecar proxy intercepts it. The sidecar then asks the control plane for routing and policy rules. Using these rules, the sidecar forwards the request to the server pod's sidecar proxy. The server pod processes the request normally without code changes. The response travels back through the sidecars, enabling logging and observability. This setup centralizes communication management and improves security and control without changing application code.