OAuth Integrations for Edge Environments

Implement GitHub and Microsoft OAuth in Cloudflare Workers and other edge runtimes.

GitHub OAuth

Required Headers

GitHub API has strict requirements that differ from other providers.

Header	Requirement
User-Agent	REQUIRED - Returns 403 without it
Accept	application/vnd.github+json recommended

const resp = await fetch('https://api.github.com/user', {
  headers: {
    Authorization: `Bearer ${accessToken}`,
    'User-Agent': 'MyApp/1.0',  // Required!
    'Accept': 'application/vnd.github+json',
  },
});

Private Email Handling

GitHub users can set email to private (/user returns email: null).

if (!userData.email) {
  const emails = await fetch('https://api.github.com/user/emails', { headers })
    .then(r => r.json());
  userData.email = emails.find(e => e.primary && e.verified)?.email;
}

Requires user:email scope.

Token Exchange

Token exchange returns form-encoded by default. Add Accept header for JSON:

const tokenResponse = await fetch('https://github.com/login/oauth/access_token', {
  method: 'POST',
  headers: {
    'Content-Type': 'application/x-www-form-urlencoded',
    'Accept': 'application/json',  // Get JSON response
  },
  body: new URLSearchParams({ code, client_id, client_secret, redirect_uri }),
});

GitHub OAuth Notes

Issue	Solution
Callback URL	Must be EXACT - no wildcards, no subdirectory matching
Token exchange returns form-encoded	Add 'Accept': 'application/json' header
Tokens don't expire	No refresh flow needed, but revoked = full re-auth

Microsoft Entra (Azure AD) OAuth

Why MSAL Doesn't Work in Workers

MSAL.js depends on:

• Browser APIs (localStorage, sessionStorage, DOM)
• Node.js crypto module

Cloudflare's V8 isolate runtime has neither. Use manual OAuth instead:

1. Manual OAuth URL construction
2. Direct token exchange via fetch
3. JWT validation with jose library

Required Scopes

// For user identity (email, name, profile picture)
const scope = 'openid email profile User.Read';

// For refresh tokens (long-lived sessions)
const scope = 'openid email profile User.Read offline_access';

Critical: User.Read is required for Microsoft Graph /me endpoint. Without it, token exchange succeeds but user info fetch returns 403.

User Info Endpoint

// Microsoft Graph /me endpoint
const resp = await fetch('https://graph.microsoft.com/v1.0/me', {
  headers: { Authorization: `Bearer ${accessToken}` },
});

// Email may be in different fields
const email = data.mail || data.userPrincipalName;

Tenant Configuration

Tenant Value	Who Can Sign In
common	Any Microsoft account (personal + work)
organizations	Work/school accounts only
consumers	Personal Microsoft accounts only
{tenant-id}	Specific organization only

Azure Portal Setup

1. App Registration → New registration
2. Platform: Web (not SPA) for server-side OAuth
3. Redirect URIs: Add both /callback and /admin/callback
4. Certificates & secrets → New client secret

Token Lifetimes

Token Type	Default Lifetime	Notes
Access token	60-90 minutes	Configurable via token lifetime policies
Refresh token	90 days	Revoked on password change
ID token	60 minutes	Same as access token

Best Practice: Always request offline_access scope and implement refresh token flow for sessions longer than 1 hour.

Common Corrections

If Claude suggests...	Use instead...
GitHub fetch without User-Agent	Add 'User-Agent': 'AppName/1.0' (REQUIRED)
Using MSAL.js in Workers	Manual OAuth + jose for JWT validation
Microsoft scope without User.Read	Add User.Read scope
Fetching email from token claims only	Use Graph /me endpoint

Error Reference

GitHub Errors

Error	Cause	Fix
403 Forbidden	Missing User-Agent header	Add User-Agent header
email: null	User has private email	Fetch /user/emails with user:email scope

Microsoft Errors

Error	Cause	Fix
AADSTS50058	Silent auth failed	Use interactive flow
AADSTS700084	Refresh token expired	Re-authenticate user
403 on Graph /me	Missing User.Read scope	Add User.Read to scopes

Reference

• GitHub API: https://docs.github.com/en/rest
• GitHub OAuth: https://docs.github.com/en/apps/oauth-apps
• Microsoft Graph permissions: https://learn.microsoft.com/en-us/graph/permissions-reference
• AADSTS error codes: https://learn.microsoft.com/en-us/entra/identity-platform/reference-error-codes