Shield WAF reference
Arcjet Shield WAF protects your application against common attacks, including the OWASP Top 10.
Configuration
Section titled “Configuration”Shield is configured by specifying which mode you want it to run in.
The arcjet client can be configured with one or more Shield rules, which are
constructed with the shield(options: ShieldOptions) function and configured by
ShieldOptions:
type ShieldOptions = { mode?: ArcjetMode | undefined;};type ArcjetMode = "LIVE" | "DRY_RUN";Loader versus action
Remix does not support middleware, instead they recommend calling functions directly inside the loader. Loaders execute before the page is loaded.
All our examples use this pattern, but you can also execute Arcjet in an
action. This would be appropriate
to protect a form submission or other non-GET request.
For example, you might want to run Shield on every GET page load, but use
Shield and email validation in an action handling a form POST.
Action
This example shows how to run Arcjet in a Remix action:
import arcjet, { shield } from "@arcjet/remix";import type { ActionFunctionArgs } from "@remix-run/node";import { redirect } from "@remix-run/node";
const aj = arcjet({ key: process.env.ARCJET_KEY!, rules: [ shield({ mode: "LIVE", }), ],});
export async function action(args: ActionFunctionArgs) { const decision = await aj.protect(args);
if (decision.isDenied()) { // This redirects to a generic error page (which you should create), but you // could also throw an error return redirect(`/error`); }
// ... // Process the action here // ...
return null;}import arcjet, { shield } from "@arcjet/remix";import { redirect } from "@remix-run/node";
const aj = arcjet({ key: process.env.ARCJET_KEY, rules: [ shield({ mode: "LIVE", }), ],});
export async function action(args) { const decision = await aj.protect(args);
if (decision.isDenied()) { // This redirects to a generic error page (which you should create), but you // could also throw an error return redirect(`/error`); }
// ... // Process the action here // ...
return null;}Decision
Section titled “Decision”Arcjet provides a single protect function that is used to execute your
protection rules. This requires a RequestEvent property which is the event
context as passed to the request handler.
This function returns a Promise that resolves to an
ArcjetDecision object. This contains the following properties:
id(string) – The unique ID for the request. This can be used to look up the request in the Arcjet dashboard. It is prefixed withreq_for decisions involving the Arcjet cloud API. For decisions taken locally, the prefix islreq_.conclusion(ArcjetConclusion) – The final conclusion based on evaluating each of the configured rules. If you wish to accept Arcjet’s recommended action based on the configured rules then you can use this property.reason(ArcjetReason) – An object containing more detailed information about the conclusion.results(ArcjetRuleResult[]) – An array ofArcjetRuleResultobjects containing the results of each rule that was executed.ip(ArcjetIpDetails) – An object containing Arcjet’s analysis of the client IP address. For more information, see the SDK reference.
To check whether a shield rule returned a deny conclusion, use
decision.isDenied() and decision.reason.isShield() (JS) /
decision.is_denied() and decision.reason_v2.type == "SHIELD" (Python).
You can iterate through the results and check whether a shield rule was applied:
for (const result of decision.results) { console.log("Rule Result", result);}for result in decision.results: print("Rule Result", result)This example logs the full result as well as the shield rule:
import arcjet, { shield, fixedWindow } from "@arcjet/remix";import type { LoaderFunctionArgs } from "@remix-run/node";
const aj = arcjet({ key: process.env.ARCJET_KEY!, // Get your site key from https://console.arcjet.com rules: [ fixedWindow({ mode: "LIVE", window: "1h", max: 60, }), shield({ mode: "LIVE", }), ],});
export async function loader(args: LoaderFunctionArgs) { const decision = await aj.protect(args);
for (const result of decision.results) { console.log("Rule Result", result);
if (result.reason.isRateLimit()) { console.log("Rate limit rule", result); }
if (result.reason.isShield()) { console.log("Shield protection rule", result); } }
if (decision.isDenied()) { if (decision.reason.isRateLimit()) { throw new Response("Too Many Requests", { status: 429, statusText: "Too Many Requests", }); } else { throw new Response("Forbidden", { status: 403, statusText: "Forbidden" }); } }
return null;}import arcjet, { shield, fixedWindow } from "@arcjet/remix";
const aj = arcjet({ key: process.env.ARCJET_KEY, // Get your site key from https://console.arcjet.com rules: [ fixedWindow({ mode: "LIVE", window: "1h", max: 60, }), shield({ mode: "LIVE", }), ],});
export async function loader(args) { const decision = await aj.protect(args);
for (const result of decision.results) { console.log("Rule Result", result);
if (result.reason.isRateLimit()) { console.log("Rate limit rule", result); }
if (result.reason.isShield()) { console.log("Shield protection rule", result); } }
if (decision.isDenied()) { if (decision.reason.isRateLimit()) { throw new Response("Too Many Requests", { status: 429, statusText: "Too Many Requests", }); } else { throw new Response("Forbidden", { status: 403, statusText: "Forbidden" }); } }
return null;}Error handling
Section titled “Error handling”Arcjet is designed to fail open so that a service issue or misconfiguration does not block all requests. The SDK also times out and fails open after 2000 ms by default. However, in most cases, the response time is less than 20 ms to 30 ms.
If there is an error condition when processing the rule, Arcjet returns an
ERROR result for that rule and you can check the message property on the
rule’s error result for more information.
If all other rules that were run returned an ALLOW result, then the final
Arcjet conclusion is ERROR.
import arcjet, { shield } from "@arcjet/remix";import type { LoaderFunctionArgs } from "@remix-run/node";
const aj = arcjet({ key: process.env.ARCJET_KEY!, // Get your site key from https://console.arcjet.com rules: [ shield({ mode: "LIVE", // will block requests. Use "DRY_RUN" to log only }), ],});
export async function loader(args: LoaderFunctionArgs) { const decision = await aj.protect(args);
for (const { reason } of decision.results) { if (reason.isError()) { // Fail open by logging the error and continuing console.warn("Arcjet error", reason.message); // You could also fail closed here for very sensitive routes // throw new Response("Service unavailable", { status: 503, statusText: "Service unavailable" }); } }
if (decision.isDenied()) { throw new Response("Forbidden", { status: 403, statusText: "Forbidden" }); }
return null;}import arcjet, { shield } from "@arcjet/remix";
const aj = arcjet({ key: process.env.ARCJET_KEY, // Get your site key from https://console.arcjet.com rules: [ shield({ mode: "LIVE", // will block requests. Use "DRY_RUN" to log only }), ],});
export async function loader(args) { const decision = await aj.protect(args);
for (const { reason } of decision.results) { if (reason.isError()) { // Fail open by logging the error and continuing console.warn("Arcjet error", reason.message); // You could also fail closed here for very sensitive routes // throw new Response("Service unavailable", { status: 503, statusText: "Service unavailable" }); } }
if (decision.isDenied()) { throw new Response("Forbidden", { status: 403, statusText: "Forbidden" }); }
return null;}Testing
Section titled “Testing”Arcjet runs the same in any environment, including locally and in CI. You can
use the mode set to DRY_RUN to log the results of rule execution without
blocking any requests.
We have an example test framework you can use to automatically test your rules. Arcjet can also be triggered based using a sample of your traffic.
For details, see the Testing section of the docs.