Open sourcing our Sentry SSO plugin


Cloudflare Access, part of Cloudflare for Teams, replaces legacy corporate VPNs with Cloudflare’s global network. Using your existing identity provider, Access enables your end users to login from anywhere — without a clunky agent or traffic backhaul through a centralized appliance or VPN.

Today, we are open sourcing a plugin that continues to improve that experience by making it easier for teams to use Cloudflare Access with one of the software industry’s most popular engineering tools, Sentry.

What is Sentry?

Sentry is an application that helps software teams find and diagnose errors in their products. We use Sentry here at Cloudflare. When you encounter an error when using a Cloudflare product, like our dashboard, we log that event. We then use Sentry to determine what went wrong.

Sentry can categorize and roll up errors, making it easy to identify new problems before investigating them with the tool’s event logging. Engineering managers here can use the dashboards to monitor the health of a new release. Product managers often use those reports as part of prioritizing what to fix next. Engineers on our team can dig into the individual errors as they release a fix.

Sentry is available in two forms: a SaaS model and a self-hosted version. Both modes give engineering teams comprehensive insight into the behavior of their deployed applications and the issues their users encounter.

Connecting users to Sentry

Organizations can deploy the self-hosted version on-premise or in a cloud environment they control. However, they still need to create a secure way to allow their teams to connect to the app.

Historically, most opt for a VPN to solve that challenge. End users outside of the office need to configure a VPN client on their laptop and try to login with credentials that are often different from the ones used for a corporate SSO. Administrators had to make sure their VPN appliance could scale for a few users, but with most in the office, the VPN was a serious inconvenience for a smaller set of users.

Over the last few years, that group of users working outside of the office has grown. Users are working from BYOD laptops, mobile phones, and in unfamiliar networks that all struggle with a VPN. Even worse, a VPN has a load limit because it relies on an actual appliance (whether virtual or physical hardware). Organizations can attempt to stress test their VPN, but will always have a limit that administrators need to continuously monitor.

Cloudflare Access gives administrators the scale of Cloudflare’s global network and provides end users with a SaaS-like experience that just works from any device or network. When teams secure Sentry with Cloudflare Access, end users visit the hostname of the application, login with their identity provider, and are redirected from Cloudflare’s edge to the app if they have permission to reach it.

However, in the case of an app like Sentry, end users need to login one more time to the application itself. That small step adds real friction, which Access can now solve through this open source plugin.

JWT Security with Cloudflare for Teams

When a user logs in to their identity provider when connecting to an application protected by Access, Cloudflare signs a JSON Web Token (JWT).

Cloudflare Access uses that JWT, and its contents, to confirm a user identity before allowing or denying access to sensitive resources. Cloudflare securely creates these through the OAUTH or SAML integration between Cloudflare Access and the configured identity provider. Each JWT consists of three Base64-URL strings: the header, the payload, and the signature.

  • The header defines the cryptographic operation that encrypts the data in the JWT.
  • The payload consists of name-value pairs for at least one and typically multiple claims, encoded in JSON. For example, the payload can contain the identity of a user
  • The signature allows the receiving party to confirm that the payload is authentic.

The token is signed using a public private key pair and saved in the user’s browser. Inside of that token, we store the following details in addition to some general metadata:

  • User identity: typically the email address of the user retrieved from your identity provider.
  • Authentication domain: the domain that signs the token. For Access, we use “example.cloudflareaccess.com” where “example” is a subdomain you can configure.
  • Audience: The domain of the application you are attempting to reach.
  • Expiration: the time at which the token is no longer valid for use.

When a request is made to an application behind Access, Cloudflare looks for the presence of that token. If available, we decrypt it, validate its authenticity, and then read the payload. If the payload contains information about a user who should be able to reach the application, we send their request to an origin.

The Sentry plugin takes that JWT and reuses it, instead of prompting the visitor to login again with separate credentials. The plugin parses the user identity, checks it against the directory of users in Sentry, and maps that token to a Sentry profile and its assigned permissions.

All of this is seamless to the end user and takes just a few milliseconds. The user is instantly redirected to the application, fully authenticated, and only needs to remember their SSO login. Administrators now have one fewer set of credentials to worry about managing and the associated onboarding and offboarding.

Building your own SSO plugin

We believe that the JSON Web Token is a simple and efficient method for sending identity. Applications that use JWTs for authorization only need to support the JWT standard, instead of attempting to integrate with different versions of SAML or other formats like OIDC and OAUTH. A JWT is also information dense and built in a format, JSON, that can be easily parsed by the target application.

Some products, like Redash, already have native support for JWT integration. The Sentry plugin we built joins our Atlassian plugin as both options to extend support to those apps, but also examples that can be used for integration with other products. Other teams, like Auth0, have also published materials to add JWT integration to legacy apps.

What’s next?

Cloudflare Access is available on every Cloudflare account and 5 free seats are included by default. You can follow these instructions to get started.

If you are a small business, you can sign up for the Cloudflare for Teams program right now at the link below.

https://www.cloudflare.com/smallbusiness/



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