Migrating from Mountebank to Rift

Rift is designed as a drop-in replacement for Mountebank. This guide covers the migration process and highlights any differences.

Compatibility Overview

Rift maintains full compatibility with Mountebank’s HTTP/HTTPS protocol support:

Feature Mountebank Rift Notes
HTTP Imposters Yes Yes Fully compatible
HTTPS Imposters Yes Yes Fully compatible
REST API Yes Yes Same endpoints
JSON Configuration Yes Yes Same format
All Predicates Yes Yes equals, contains, matches, exists, etc.
JSONPath Yes Yes Same syntax
XPath Yes Yes Same syntax
Behaviors Yes Yes wait, decorate, copy, lookup
Proxy Mode Yes Yes Record and replay
Injection Yes Yes JavaScript functions
TCP Protocol Yes Planned Coming soon
SMTP Protocol Yes Planned Coming soon

Migration Steps

Step 1: Replace the Docker Image

If using Docker, simply change the image:

# Before (Mountebank)
services:
  mountebank:
    image: bbyars/mountebank:2.9.2
    ports:
      - "2525:2525"
    command: ["start", "--allowInjection"]

# After (Rift)
services:
  rift:
    image: ghcr.io/etacassiopeia/rift-proxy:latest
    ports:
      - "2525:2525"
    environment:
      - MB_ALLOW_INJECTION=true

Step 2: Use Your Existing Configuration

Rift reads Mountebank configuration files directly:

# Mountebank
mb start --configfile imposters.json

# Rift
docker run -v $(pwd)/imposters.json:/imposters.json \
  ghcr.io/etacassiopeia/rift-proxy:latest --configfile /imposters.json

Step 3: Update Environment Variables

Map Mountebank CLI options to Rift environment variables:

Mountebank CLI Rift Environment Variable
--port 2525 MB_PORT=2525
--allowInjection MB_ALLOW_INJECTION=true
--configfile --configfile (CLI)
--loglevel debug RUST_LOG=debug

Step 4: Verify Functionality

Run your existing test suite against Rift:

# Your tests should work without modification
npm test
pytest
go test ./...

Feature Differences

Enhanced Performance

Rift provides significantly better performance:

  • 20-250x faster request processing
  • Consistent latency regardless of stub count
  • Lower memory usage due to Rust’s efficiency

Additional Features

Rift includes features not in Mountebank:

  1. Native Metrics: Built-in Prometheus metrics on /metrics
  2. Rhai Scripting: Lightweight embedded scripting (in addition to JavaScript)
  3. Lua Scripting: High-performance Lua engine option
  4. Flow State: Stateful testing with Redis backend support

Minor Differences

Area Mountebank Rift
Logging Custom format Structured JSON (configurable)
Metrics Third-party Built-in Prometheus
Admin UI Built-in web UI API only (UI planned)

Configuration Examples

Mountebank CLI to Rift 

# Mountebank
mb start \
  --port 2525 \
  --allowInjection \
  --loglevel warn \
  --configfile imposters.json

# Rift (equivalent)
docker run \
  -e MB_PORT=2525 \
  -e MB_ALLOW_INJECTION=true \
  -e RUST_LOG=warn \
  -v $(pwd)/imposters.json:/imposters.json \
  ghcr.io/etacassiopeia/rift-proxy:latest \
  --configfile /imposters.json

Docker Compose 

version: '3.8'

services:
  rift:
    image: ghcr.io/etacassiopeia/rift-proxy:latest
    ports:
      - "2525:2525"      # Admin API
      - "4545:4545"      # Imposter port
      - "9090:9090"      # Metrics (Rift addition)
    environment:
      - MB_PORT=2525
      - MB_ALLOW_INJECTION=true
      - RUST_LOG=info
    volumes:
      - ./imposters.json:/imposters.json
    command: ["--configfile", "/imposters.json"]

Troubleshooting

“Injection not allowed”

Enable injection via environment variable:

docker run -e MB_ALLOW_INJECTION=true ghcr.io/etacassiopeia/rift-proxy:latest

Different Response Format

Rift may format JSON responses differently (but equivalently). If your tests compare exact string output, consider comparing parsed JSON instead.

Missing TCP/SMTP Protocol

These protocols are planned but not yet implemented. For now, continue using Mountebank for TCP/SMTP mocking.

Getting Help