Logs

DoubleDino Proxy can expose log files safely by transforming sensitive information before returning results.

Logs can contain:

• Plain text.
• JSON logs.
• Mixed text and JSON content.

DoubleDino processes the content and returns transformed output while preserving the original structure where possible.

Endpoint

Use:

/logs

Basic query

Retrieve recent log lines using:

lines

Example:

curl

curl -G "http://localhost:8080/logs" \
  --data-urlencode "lines=10" \
  -H "x-api-key: your-api-key"

Node.js / Bun

const response = await fetch(
  "http://localhost:8080/logs?lines=10",
  {
    headers: {
      "x-api-key": "your-api-key"
    }
  }
);

const data = await response.json();

console.log(data);

Python

import requests

response = requests.get(
    "http://localhost:8080/logs",
    params={
        "lines": 10
    },
    headers={
        "x-api-key": "your-api-key"
    }
)

print(response.json())

Plain text logs

DoubleDino can transform unstructured log lines.

Example:

Original:

2026-07-21 08:15:40 [ERROR] User login failure for [email protected]

Returned:

2026-07-21 08:15:40 [ERROR] User login failure for [email protected]

The log format remains readable while sensitive values are transformed.

JSON logs

DoubleDino automatically handles structured JSON logs.

Example:

Original:

{
  "event": "checkout_completed",
  "payload": {
    "customer": "Hiroshi Tanaka",
    "email": "[email protected]",
    "amount": 4250.45
  }
}

Returned:

{
  "event": "checkout_completed",
  "payload": {
    "customer": "Xk92Lm",
    "email": "[email protected]",
    "amount": 4250.45
  }
}

JSON structure is preserved.

Mixed log files

Real production log files often contain different formats together.

Example:

2026-07-21 08:12:01 [INFO] Server booted successfully

{
  "event": "checkout_completed",
  "email": "[email protected]"
}

2026-07-21 08:25:59 [INFO] Worker completed

DoubleDino handles mixed content and transforms each entry appropriately.

Debugging production issues

Logs are often the fastest way to investigate production problems.

Example:

A developer receives:

Order INV-9921-X failed during checkout

They can inspect recent logs through DoubleDino:

curl -G "http://localhost:8080/logs" \
  --data-urlencode "lines=100" \
  -H "x-api-key: your-api-key"

The returned logs remain useful for debugging while sensitive values are transformed.

Preserving known expressions

Logs support preserved expressions.

If enabled, known phrases can remain visible:

DD_PRESERVED_EXPRESSIONS

Example:

Original:

Customer verification check failed

Returned:

Xk92Lm verification check failed

Excluding JSON keys

For structured JSON logs, known keys can be excluded from transformation.

Example:

DD_EXCLUDE_KEYS=status,code,request_id

Original:

{
  "status": 500,
  "request_id": "abc123",
  "email": "[email protected]"
}

Returned:

{
  "status": 500,
  "request_id": "abc123",
  "email": "[email protected]"
}

Dynamic expressions

If enabled by your administrator:

DD_ALLOW_DYNAMIC_EXPRESSIONS=true

you can provide additional preserved expressions per request.

Example:

-H "x-preserve-expressions: payment_gateway_rejected"

This is useful during active investigations.

Notes

• DoubleDino does not modify log files.
• Original log files remain unchanged.
• Returned content is transformed before leaving DoubleDino.
• JSON structure is preserved.
• Mixed text and JSON logs are supported.

Next steps

Continue with:

• API Reference
• Data transformation behaviour