Migration Guide

Migrate from Varnish

Zero downtime. Run in parallel. Rollback anytime.
Most migrations complete in under a day.

Simple TOML ConfigSame Cache HeadersParallel Testing

Why Teams Migrate

Simple TOML Config

Clean, declarative configuration in just 40 lines. Any developer can maintain it.

91% Less RAM

With zstd compression, you need 10x less hardware for the same cache capacity.

Native Cache Tags

Tags, soft purge, and request coalescing included in all plans.

Memory Safety

Built in Rust with compile-time safety guarantees. Modern, secure foundation.

34x Faster Purge

Soft purge with stale-while-revalidate. Users never wait for backend.

Modern Operations

REST API for everything. Prometheus metrics. No CLI gymnastics.

Migration Steps

1

Install Trident

5 minutes

Download and install Trident alongside existing Varnish.

# Docker
docker pull trident/velocity-engine:latest

# Or binary
curl -sSL https://get.trident.dev | sh
2

Create TOML Config

30 minutes

Translate your VCL settings to TOML. Most configs are 10x shorter.

# trident.toml
[server]
listen = "0.0.0.0:8081"  # Different port for testing

[cache]
max_memory = "4GB"
default_ttl = "1h"
grace_period = "24h"

[[backends]]
name = "origin"
host = "your-backend.example.com"
port = 443
tls = true
3

Test in Parallel

2-4 hours

Run Trident on a different port. Compare responses with Varnish.

# Start Trident on port 8081
trident --config /etc/trident/trident.toml

# Compare responses
curl -I http://localhost:6081/products/123  # Varnish
curl -I http://localhost:8081/products/123  # Trident

# Verify headers match
# X-Cache: HIT/MISS should be identical
4

Shift Traffic Gradually

1-2 days

Use load balancer to shift 10%, then 50%, then 100% to Trident.

# nginx load balancer example
upstream cache {
    server trident:80 weight=10;  # 10% to Trident
    server varnish:80 weight=90;  # 90% to Varnish
}

# Increase Trident weight as confidence grows
# Monitor error rates, latency, hit ratios
5

Retire Varnish

1 hour

Once 100% traffic is on Trident, decommission Varnish.

# Final steps
1. Update purge scripts to use Trident API
2. Update monitoring dashboards
3. Remove Varnish from infrastructure
4. Enjoy the simpler operations!

VCL to TOML Translation

Varnish VCL

vcl 4.1;

backend default {
    .host = "backend.example.com";
    .port = "443";
    .ssl = true;
}

sub vcl_recv {
    if (req.http.Cookie ~ "session") {
        return (pass);
    }
    if (req.http.Authorization) {
        return (pass);
    }
}

sub vcl_backend_response {
    set beresp.ttl = 1h;
    set beresp.grace = 24h;

    if (beresp.http.Cache-Control ~ "no-cache") {
        set beresp.uncacheable = true;
    }
}

sub vcl_deliver {
    if (obj.hits > 0) {
        set resp.http.X-Cache = "HIT";
    } else {
        set resp.http.X-Cache = "MISS";
    }
}

Trident TOML

# trident.toml

[[backends]]
name = "default"
host = "backend.example.com"
port = 443
tls = true

[cache]
default_ttl = "1h"
grace_period = "24h"

# Session/auth bypass is automatic!
# No config needed - secure by default

[response_headers]
x_cache = true

# That's it! 15 lines vs 35 lines
# And no scripting language to learn

Most VCL features are built-in defaults in Trident. You don't need to configure them.

Common VCL Patterns

Cache Tags (Varnish Plus)

Varnish Plus (€30K/year)

# Requires commercial license
import xkey;
sub vcl_backend_response {
    set beresp.http.xkey =
        beresp.http.X-Cache-Tags;
}

Trident (All plans)

# Just works! No config needed.
# Tags from X-Cache-Tags header
# are automatically indexed.

Health Checks

Varnish VCL

probe health {
    .url = "/health";
    .interval = 5s;
    .timeout = 2s;
    .window = 5;
    .threshold = 3;
}
backend default {
    .host = "backend";
    .probe = health;
}

Trident TOML

[[backends]]
name = "default"
host = "backend"
health_check_path = "/health"
health_check_interval = "5s"

Strip Tracking Params

Varnish VCL

sub vcl_recv {
    set req.url = regsuball(
        req.url,
        "(\?|&)(utm_[^&]+|fbclid=[^&]+)",
        ""
    );
}

Trident TOML

[cache.key]
ignore_query_params = [
    "utm_*",
    "fbclid",
    "gclid"
]

Zero-Risk Rollback

Migration not going as planned? Roll back instantly by shifting traffic back to Varnish. No data loss, no downtime.

Parallel Running

Both caches run simultaneously during migration

Instant Rollback

Shift traffic back in seconds via load balancer

Compare Metrics

Monitor both systems before committing

Migration Support

Self-Service

  • ✓Documentation & guides
  • ✓VCL to TOML examples
  • ✓Community support
  • ✓GitHub issue tracking
Included in all plans

Assisted Migration

  • ✓Dedicated migration engineer
  • ✓VCL review & translation
  • ✓Performance benchmarking
  • ✓Production go-live support
Enterprise plans

Ready to Migrate?

Start your free trial and run Trident alongside Varnish today.

Start Free TrialTalk to Migration Team