feat(build): Add NeonDB branch resolution for Vercel preview environments

packages/build/src/extensions/core/vercelSyncEnvVars.ts

@@ -11,11 +11,192 @@ type VercelEnvVar = {
   gitBranch?: string;
 };
 
+// List of Neon DB related environment variables to sync,
+// provided by Vercel's NeonDB integration
+const NEON_ENV_VARS = [
+  "PGUSER",
+  "POSTGRES_URL_NO_SSL",
+  "POSTGRES_HOST",
+  "POSTGRES_URL",
+  "POSTGRES_PRISMA_URL",
+  "DATABASE_URL_UNPOOLED",
+  "POSTGRES_URL_NON_POOLING",
+  "PGHOST",
+  "POSTGRES_USER",
+  "DATABASE_URL",
+  "POSTGRES_PASSWORD",
+  "POSTGRES_DATABASE",
+  "PGPASSWORD",
+  "PGDATABASE",
+  "PGHOST_UNPOOLED",
+];
+const VERCEL_NEON_ENV_VAR_PREFIX = "";
+const NEON_PROJECT_ID_ENV_VAR = "NEON_PROJECT_ID";
+
+type NeonBranch = {
+  id: string;
+  name: string;
+};
+
+type NeonEndpoint = {
+  id: string;
+  host: string;
+  type: string;
+};
+
+async function fetchNeonBranchEnvVars(options: {
+  neonProjectId: string;
+  neonDbAccessToken: string;
+  branch: string;
+  vercelEnvironment: string;
+  filteredEnvs: EnvVar[];
+  vercelNeonEnvVarPrefix: string;
+}): Promise<EnvVar[] | null> {
+  const {
+    neonProjectId,
+    neonDbAccessToken,
+    branch,
+    vercelEnvironment,
+    filteredEnvs,
+    vercelNeonEnvVarPrefix,
+  } = options;
+
+  // Step 1: Search for the branch in Neon
+  const branchSearchParams = new URLSearchParams({ search: branch });
+  const branchesUrl = `https://console.neon.tech/api/v2/projects/${neonProjectId}/branches?${branchSearchParams}`;
+
+  const branchesResponse = await fetch(branchesUrl, {
+    headers: {
+      Authorization: `Bearer ${neonDbAccessToken}`,
+    },
+  });
+
+  if (!branchesResponse.ok) {
+    throw new Error(`Failed to fetch Neon branches: ${branchesResponse.status}`);
+  }
+
+  const branchesData = await branchesResponse.json();
+  const branches: NeonBranch[] = branchesData.branches || [];
+
+  if (branches.length === 0) {
+    // No matching branch found, return null to keep original env vars
+    return null;
+  }
+
+  // Neon branch names are prefixed with Vercel environment (e.g., "preview/branch-name")
+  // Filter branches to find the one with the exact matching name
+  const expectedBranchName = `${vercelEnvironment}/${branch}`;
+  const matchingBranch = branches.find((b) => b.name === expectedBranchName || b.name === branch);
+
+  if (!matchingBranch) {
+    // No exact match found, return null to keep original env vars
+    return null;
+  }
+
+  const neonBranchId = matchingBranch.id;
+
+  // Step 2: Get endpoints for the branch
+  const endpointsUrl = `https://console.neon.tech/api/v2/projects/${neonProjectId}/branches/${neonBranchId}/endpoints`;
+
+  const endpointsResponse = await fetch(endpointsUrl, {
+    headers: {
+      Authorization: `Bearer ${neonDbAccessToken}`,
+    },
+  });
+
+  if (!endpointsResponse.ok) {
+    throw new Error(`Failed to fetch Neon branch endpoints: ${endpointsResponse.status}`);
+  }
+
+  const endpointsData = await endpointsResponse.json();
+  const endpoints: NeonEndpoint[] = endpointsData.endpoints || [];
+
+  if (endpoints.length === 0) {
+    // No endpoints found, return null
+    return null;
+  }
+
+  // Find an endpoint with type containing 'write', or take the first one
+  const writeEndpoint = endpoints.find((ep) => ep.type.includes("write"));
+  const endpoint = writeEndpoint || endpoints[0];
+
+  if (!endpoint) {
+    return null;
+  }
+
+  // Step 3: Build new environment variables based on the endpoint host
+  // We need to find DATABASE_URL from filteredEnvs to extract user, password, and database name
+  const prefixedDatabaseUrlKey = `${vercelNeonEnvVarPrefix}DATABASE_URL`;
+  const databaseUrlEnv = filteredEnvs.find(
+    (env) => env.name === prefixedDatabaseUrlKey || env.name === "DATABASE_URL"
+  );
+
+  if (!databaseUrlEnv) {
+    // No DATABASE_URL found, cannot construct new env vars
+    return null;
+  }
+
+  // Parse DATABASE_URL to extract components
+  // Format: postgresql://user:password@host/database?sslmode=require
+  let parsedUrl: URL;
+  try {
+    parsedUrl = new URL(databaseUrlEnv.value);
+  } catch {
+    // Invalid URL, return null
+    return null;
+  }
+
+  const user = parsedUrl.username;
+  const password = parsedUrl.password;
+  const database = parsedUrl.pathname.slice(1); // Remove leading slash
+  const newHost = endpoint.host;
+  const poolerHost = newHost.replace(/^([^.]+)\./, "$1-pooler.");
+
+  // Build new env vars
+  const newEnvVars: EnvVar[] = [];
+
+  const envVarMappings: Record<string, string> = {
+    PGUSER: user,
+    PGPASSWORD: password,
+    PGDATABASE: database,
+    PGHOST: poolerHost,
+    PGHOST_UNPOOLED: newHost,
+    POSTGRES_USER: user,
+    POSTGRES_PASSWORD: password,
+    POSTGRES_DATABASE: database,
+    POSTGRES_HOST: poolerHost,
+    DATABASE_URL: `postgresql://${user}:${password}@${poolerHost}/${database}?sslmode=require`,
+    DATABASE_URL_UNPOOLED: `postgresql://${user}:${password}@${newHost}/${database}?sslmode=require`,
+    POSTGRES_URL: `postgresql://${user}:${password}@${poolerHost}/${database}?sslmode=require`,
+    POSTGRES_URL_NO_SSL: `postgresql://${user}:${password}@${poolerHost}/${database}`,
+    POSTGRES_URL_NON_POOLING: `postgresql://${user}:${password}@${newHost}/${database}?sslmode=require`,
+    POSTGRES_PRISMA_URL: `postgresql://${user}:${password}@${poolerHost}/${database}?sslmode=require&pgbouncer=true&connect_timeout=15`,
+  };
+
+  for (const neonEnvVar of NEON_ENV_VARS) {
+    const prefixedKey = `${vercelNeonEnvVarPrefix}${neonEnvVar}`;
+    // Only override if the env var exists in filteredEnvs
+    const envInFiltered = filteredEnvs.find((env) => env.name === prefixedKey);
+    if (envInFiltered && envVarMappings[neonEnvVar]) {
+      newEnvVars.push({
+        name: prefixedKey,
+        value: envVarMappings[neonEnvVar],
+        isParentEnv: envInFiltered.isParentEnv,
+      });
+    }
+  }
+
+  return newEnvVars;
+}
+
 export function syncVercelEnvVars(options?: {
   projectId?: string;
   vercelAccessToken?: string;
   vercelTeamId?: string;
   branch?: string;
+  neonDbAccessToken?: string;
+  neonProjectId?: string;
+  vercelNeonEnvVarPrefix?: string;
 }): BuildExtension {
   const sync = syncEnvVars(async (ctx) => {
     const projectId =
@@ -25,13 +206,18 @@ export function syncVercelEnvVars(options?: {
       process.env.VERCEL_ACCESS_TOKEN ??
       ctx.env.VERCEL_ACCESS_TOKEN ??
       process.env.VERCEL_TOKEN;
+    const neonDbAccessToken =
+      options?.neonDbAccessToken ?? process.env.NEON_ACCESS_TOKEN ?? ctx.env.NEON_ACCESS_TOKEN;
     const vercelTeamId =
       options?.vercelTeamId ?? process.env.VERCEL_TEAM_ID ?? ctx.env.VERCEL_TEAM_ID;
     const branch =
       options?.branch ??
       process.env.VERCEL_PREVIEW_BRANCH ??
       ctx.env.VERCEL_PREVIEW_BRANCH ??
       ctx.branch;
+    let neonProjectId: string | undefined =
+      options?.neonProjectId ?? process.env.NEON_PROJECT_ID ?? ctx.env.NEON_PROJECT_ID;
+    const vercelNeonEnvVarPrefix = options?.vercelNeonEnvVarPrefix ?? VERCEL_NEON_ENV_VAR_PREFIX;
 
     if (!projectId) {
       throw new Error(
@@ -79,7 +265,7 @@ export function syncVercelEnvVars(options?: {
 
       const isBranchable = ctx.environment === "preview";
 
-      const filteredEnvs: EnvVar[] = data.envs
+      let filteredEnvs: EnvVar[] = data.envs
         .filter((env: VercelEnvVar) => {
           if (!env.value) return false;
           if (!env.target.includes(vercelEnvironment)) return false;
@@ -94,6 +280,55 @@ export function syncVercelEnvVars(options?: {
           };
         });
 
+      // Discover NEON_PROJECT_ID from incoming Vercel env variables
+      const neonProjectIdEnv = filteredEnvs.find((env) => env.name === NEON_PROJECT_ID_ENV_VAR);
+      if (neonProjectIdEnv) {
+        neonProjectId = neonProjectIdEnv.value;
+      }
+
+      // Keep a copy of the original env vars for the Neon API call (to extract credentials)
+      const originalFilteredEnvs = [...filteredEnvs];
+
+      // For non-production environments, filter out Neon env vars to avoid using production database
+      // These will be replaced with branch-specific values from Neon API if available
+      if (neonProjectId) {
+        const neonEnvVarNames = new Set(
+          NEON_ENV_VARS.map((name) => `${vercelNeonEnvVarPrefix}${name}`)
+        );
+
+        if (vercelEnvironment !== "production") {
+          filteredEnvs = filteredEnvs.filter((env) => !neonEnvVarNames.has(env.name));
+        }
+      }
+
+      // If we have neonProjectId, neonDbAccessToken, and branch, fetch Neon branch info and add env vars
+      if (neonProjectId && neonDbAccessToken && branch && vercelEnvironment !== "production") {
+        try {
+          const neonBranchEnvVars = await fetchNeonBranchEnvVars({
+            neonProjectId,
+            neonDbAccessToken,
+            branch,
+            vercelEnvironment,
+            filteredEnvs: originalFilteredEnvs,
+            vercelNeonEnvVarPrefix,
+          });
+          if (neonBranchEnvVars) {
+            // Override NEON_ENV_VARS in filteredEnvs with the new values
+            for (const neonEnvVar of neonBranchEnvVars) {
+              const existingIndex = filteredEnvs.findIndex((env) => env.name === neonEnvVar.name);
+              if (existingIndex !== -1) {
+                filteredEnvs[existingIndex] = neonEnvVar;
+              } else {
+                filteredEnvs.push(neonEnvVar);
+              }
+            }
+          }
+        } catch (neonError) {
+          console.error("Error fetching Neon branch environment variables:", neonError);
+          // Continue with original filteredEnvs if Neon API fails
+        }
+      }
+
       return filteredEnvs;
     } catch (error) {
       console.error("Error fetching or processing Vercel environment variables:", error);