TLS termination with Ingress in Kubernetes - Step-by-Step Execution

Process Flow - TLS termination with Ingress

Client sends HTTPS request

↓

Ingress Controller receives request

↓

Ingress decrypts TLS (TLS Termination)

↓

Ingress forwards plain HTTP to Service

↓

Service routes to Pod

↓

Pod responds

↓

Ingress encrypts response (if needed)

↓

Client receives response

The Ingress controller handles HTTPS requests by decrypting TLS, then forwards plain HTTP to backend services, simplifying TLS management.

Execution Sample

Kubernetes

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: example-ingress
spec:
  tls:
  - hosts:
    - example.com
    secretName: tls-secret
  rules:
  - host: example.com
    http:
      paths:
      - path: /
        pathType: Prefix
        backend:
          service:
            name: example-service
            port:
              number: 80

This Ingress resource configures TLS termination for example.com using tls-secret and routes HTTP traffic to example-service.

Process Table

Step	Action	Input	Output/Result
1	Client sends HTTPS request	https://example.com	Encrypted request sent to Ingress
2	Ingress receives request	Encrypted HTTPS request	Ingress decrypts TLS using tls-secret
3	Ingress forwards request	Plain HTTP request	Request sent to example-service on port 80
4	Service routes to Pod	HTTP request	Pod receives HTTP request
5	Pod processes request	HTTP request	Pod sends HTTP response
6	Ingress sends response	HTTP response	Ingress forwards response to client (usually encrypted)
7	Client receives response	Encrypted HTTPS response	Client displays content
Exit	End of request cycle	N/A	Request completed successfully

💡 Request cycle ends after client receives the response

Status Tracker

Variable	Start	After Step 2	After Step 3	After Step 5	Final
Request State	Encrypted HTTPS	Decrypted HTTP	Plain HTTP forwarded	HTTP response generated	Encrypted HTTPS response

Key Moments - 3 Insights

Why does the Ingress decrypt the TLS instead of the backend service?

Ingress handles TLS termination to centralize certificate management and reduce complexity for backend services, as shown in step 2 and 3 of the execution table.

Is the traffic between Ingress and backend service encrypted?

No, after TLS termination, Ingress forwards plain HTTP to the backend service, as seen in step 3 and 4.

What is the role of the tls-secret in the Ingress?

The tls-secret contains the TLS certificate and key used by Ingress to decrypt incoming HTTPS requests, referenced in the execution sample and step 2.

Visual Quiz - 3 Questions

Look at the execution table, what is the state of the request after step 2?

A Decrypted HTTP

B Plain HTTP forwarded

C Encrypted HTTPS

D HTTP response generated

💡 Hint

Check the 'Output/Result' column for step 2 in the execution_table.

At which step does the backend Pod receive the request?

A Step 2

B Step 3

C Step 4

D Step 5

💡 Hint

Look for when the service routes the request to the Pod in the execution_table.

If the tls-secret is missing, what would happen at step 2?

A Ingress would forward encrypted request to backend

B Ingress would fail to decrypt TLS and reject the request

C Ingress would decrypt TLS using a default certificate

D Backend service would decrypt TLS instead

💡 Hint

Refer to the key_moments about the role of tls-secret and step 2 in the execution_table.

Concept Snapshot

TLS termination with Ingress:
- Ingress decrypts HTTPS using tls-secret
- Forwards plain HTTP to backend services
- Simplifies certificate management
- Backend services receive unencrypted traffic
- Client communication remains secure via TLS

Full Transcript

TLS termination with Ingress means the Ingress controller handles decrypting HTTPS requests using a TLS certificate stored in a secret. The client sends an encrypted HTTPS request to the Ingress. The Ingress decrypts the request and forwards it as plain HTTP to the backend service. The backend Pod processes the HTTP request and sends a response back through the Ingress, which then sends the encrypted response to the client. This setup centralizes TLS management at the Ingress, so backend services do not need to handle encryption. The tls-secret contains the certificate and key needed for decryption. If the secret is missing, the Ingress cannot decrypt TLS and will reject the request.

Practice

1. What is the main purpose of TLS termination in a Kubernetes Ingress?

easy

A. To monitor network traffic for security threats

B. To encrypt traffic between backend services

C. To generate TLS certificates automatically

D. To decrypt HTTPS traffic at the Ingress before forwarding to backend services

Solution

1. Step 1: Understand TLS termination role

   TLS termination means decrypting encrypted HTTPS traffic at a central point.

2. Step 2: Identify Ingress function

   Kubernetes Ingress can handle TLS termination by decrypting traffic before sending it to backend pods.

3. Final Answer:

   To decrypt HTTPS traffic at the Ingress before forwarding to backend services -> Option D

4. Quick Check:

   TLS termination = decrypt at Ingress [OK]

Hint: TLS termination means decrypting at Ingress, not backend [OK]

Common Mistakes:

• Confusing TLS termination with encryption between services
• Thinking Ingress generates certificates automatically
• Assuming TLS termination monitors traffic

2. Which of the following is the correct way to specify TLS in a Kubernetes Ingress YAML?

easy

A. tls:
- hosts:
- example.com
secret: tls-secret

B. tls:
- hosts:
- example.com
secretName: tls-secret

C. tls:
- host: example.com
secret: tls-secret

D. tls:
hosts: example.com
secretName: tls-secret

Solution

1. Step 1: Review TLS section syntax

   The correct syntax uses a list under tls with hosts as a list and secretName key.

2. Step 2: Compare options

   tls: - hosts: - example.com secretName: tls-secret matches the correct YAML structure with 'secretName' and hosts list.

3. Final Answer:

   tls: - hosts: - example.com secretName: tls-secret -> Option B

4. Quick Check:

   Correct TLS YAML uses secretName and hosts list [OK]

Hint: Use 'secretName' and list under 'hosts' in tls section [OK]

Common Mistakes:

• Using 'secret' instead of 'secretName'
• Not using a list for hosts
• Incorrect indentation or missing dash

3. Given this Ingress snippet:

tls:
  - hosts:
    - myapp.example.com
    secretName: myapp-tls

rules:
  - host: myapp.example.com
    http:
      paths:
      - path: /
        pathType: Prefix
        backend:
          service:
            name: myapp-service
            port:
              number: 80

What happens when a user accesses https://myapp.example.com?

medium

A. The Ingress decrypts TLS and forwards HTTP traffic to myapp-service on port 80

B. The Ingress forwards encrypted TLS traffic directly to myapp-service

C. The Ingress rejects the connection because backend port is 80

D. The Ingress terminates TLS but forwards HTTPS traffic to backend

Solution

1. Step 1: Understand TLS termination in Ingress

   The Ingress uses the secret to decrypt HTTPS traffic for the host.

2. Step 2: Check backend service port and protocol

   The backend service listens on port 80 (HTTP), so decrypted HTTP traffic is forwarded.

3. Final Answer:

   The Ingress decrypts TLS and forwards HTTP traffic to myapp-service on port 80 -> Option A

4. Quick Check:

   Ingress decrypts TLS, backend gets HTTP [OK]

Hint: Ingress decrypts TLS, backend usually gets HTTP on port 80 [OK]

Common Mistakes:

• Assuming backend receives encrypted traffic
• Thinking backend must use HTTPS port
• Confusing TLS termination with passthrough

4. You configured TLS in your Ingress but HTTPS requests fail with a certificate error. What is the most likely cause?

medium

A. The secret referenced in tls section does not contain a valid TLS certificate

B. The backend service is not listening on port 443

C. The Ingress controller does not support TLS termination

D. The Ingress resource is missing the rules section

Solution

1. Step 1: Check TLS secret validity

   If the secret does not have a valid TLS cert and key, HTTPS will fail with certificate errors.

2. Step 2: Verify other options

   Backend port or missing rules do not cause cert errors; controller usually supports TLS.

3. Final Answer:

   The secret referenced in tls section does not contain a valid TLS certificate -> Option A

4. Quick Check:

   Invalid TLS secret = cert error [OK]

Hint: Check TLS secret contents first for certificate errors [OK]

Common Mistakes:

• Blaming backend port for TLS cert errors
• Assuming Ingress controller lacks TLS support
• Ignoring TLS secret correctness

5. You want to secure multiple domains with TLS termination using a single Ingress resource. Which approach is correct?

hard

A. Use one tls entry with multiple hosts but different secrets for each host

B. Create separate Ingress resources for each domain with their own TLS secrets

C. Add multiple entries under the tls section with hosts and a single secret containing SAN certificates

D. Configure TLS only on backend services, not on Ingress

Solution

1. Step 1: Understand TLS with multiple hosts

   A single secret can contain a certificate with multiple Subject Alternative Names (SANs) for multiple domains.

2. Step 2: Configure Ingress tls section

   The tls field is a list, so add multiple entries under tls, each with a hosts list and referencing the same secretName containing the SAN cert.

3. Final Answer:

   Add multiple entries under the tls section with hosts and a single secret containing SAN certificates -> Option C

4. Quick Check:

   Multiple tls entries share SAN secret [OK]

Hint: Multiple tls entries can share one SAN cert secret [OK]

Common Mistakes:

• Trying different secrets for each host in one tls entry
• Creating many Ingress resources unnecessarily
• Not using SAN certificates for multiple domains