OAuth Integrations for Edge Environments Skill

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:

Manual OAuth URL construction
Direct token exchange via fetch
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

App Registration → New registration
Platform: Web (not SPA) for server-side OAuth
Redirect URIs: Add both /callback and /admin/callback
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

Agent Skills: OAuth Integrations for Edge Environments

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