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feat(@vercel/edge-config) Enforce an IO boundary around client APIs #878

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a14cdf5
[Edge Config] Enforce an IO boundary around client APIs
gnoff Sep 26, 2025
907e541
The boundary await has to happen before we read from any in memory cache
gnoff Sep 29, 2025
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5 changes: 5 additions & 0 deletions .changeset/good-teeth-film.md
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Original file line number Diff line number Diff line change
@@ -0,0 +1,5 @@
---
'@vercel/edge-config': patch
---

make sure config reads are considered IO consistnetly
365 changes: 193 additions & 172 deletions packages/edge-config/src/index.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,7 @@ import type {
} from './types';
import { fetchWithCachedResponse } from './utils/fetch-with-cached-response';
import { trace } from './utils/tracing';
import { withIOBoundary } from './utils/io-boundary';

export { setTracerProvider } from './utils/tracing';

Expand Down Expand Up @@ -342,189 +343,209 @@ export const createClient = trace(
);

const api: Omit<EdgeConfigClient, 'connection'> = {
get: trace(
async function get<T = EdgeConfigValue>(
key: string,
localOptions?: EdgeConfigFunctionsOptions,
): Promise<T | undefined> {
const localEdgeConfig =
(await getInMemoryEdgeConfig(localOptions)) ||
(await getLocalEdgeConfig(connection, localOptions));

assertIsKey(key);
if (isEmptyKey(key)) return undefined;

if (localEdgeConfig) {
// We need to return a clone of the value so users can't modify
// our original value, and so the reference changes.
//
// This makes it consistent with the real API.
return Promise.resolve(localEdgeConfig.items[key] as T);
}

const localHeaders = new Headers(headers);
if (localOptions?.consistentRead)
addConsistentReadHeader(localHeaders);

return fetchWithCachedResponse(
`${baseUrl}/item/${key}?version=${version}`,
{
headers: localHeaders,
cache: fetchCache,
},
).then<T | undefined, undefined>(async (res) => {
if (res.ok) return res.json();
await consumeResponseBody(res);

if (res.status === 401) throw new Error(ERRORS.UNAUTHORIZED);
if (res.status === 404) {
// if the x-edge-config-digest header is present, it means
// the edge config exists, but the item does not
if (res.headers.has('x-edge-config-digest')) return undefined;
// if the x-edge-config-digest header is not present, it means
// the edge config itself does not exist
throw new Error(ERRORS.EDGE_CONFIG_NOT_FOUND);
get: withIOBoundary(
trace(
async function get<T = EdgeConfigValue>(
key: string,
localOptions?: EdgeConfigFunctionsOptions,
): Promise<T | undefined> {
const localEdgeConfig =
(await getInMemoryEdgeConfig(localOptions)) ||
(await getLocalEdgeConfig(connection, localOptions));

assertIsKey(key);
if (isEmptyKey(key)) return undefined;

if (localEdgeConfig) {
// We need to return a clone of the value so users can't modify
// our original value, and so the reference changes.
//
// This makes it consistent with the real API.
return Promise.resolve(localEdgeConfig.items[key] as T);
}
if (res.cachedResponseBody !== undefined)
return res.cachedResponseBody as T;
throw new UnexpectedNetworkError(res);
});
},
{ name: 'get', isVerboseTrace: false, attributes: { edgeConfigId } },
),
has: trace(
async function has(
key,
localOptions?: EdgeConfigFunctionsOptions,
): Promise<boolean> {
const localEdgeConfig =
(await getInMemoryEdgeConfig(localOptions)) ||
(await getLocalEdgeConfig(connection, localOptions));

assertIsKey(key);
if (isEmptyKey(key)) return false;

if (localEdgeConfig) {
return Promise.resolve(hasOwnProperty(localEdgeConfig.items, key));
}

const localHeaders = new Headers(headers);
if (localOptions?.consistentRead)
addConsistentReadHeader(localHeaders);

// this is a HEAD request anyhow, no need for fetchWithCachedResponse
return fetch(`${baseUrl}/item/${key}?version=${version}`, {
method: 'HEAD',
headers: localHeaders,
cache: fetchCache,
}).then((res) => {
if (res.status === 401) throw new Error(ERRORS.UNAUTHORIZED);
if (res.status === 404) {
// if the x-edge-config-digest header is present, it means
// the edge config exists, but the item does not
if (res.headers.has('x-edge-config-digest')) return false;
// if the x-edge-config-digest header is not present, it means
// the edge config itself does not exist
throw new Error(ERRORS.EDGE_CONFIG_NOT_FOUND);
}
if (res.ok) return true;
throw new UnexpectedNetworkError(res);
});
},
{ name: 'has', isVerboseTrace: false, attributes: { edgeConfigId } },
const localHeaders = new Headers(headers);
if (localOptions?.consistentRead)
addConsistentReadHeader(localHeaders);

return fetchWithCachedResponse(
`${baseUrl}/item/${key}?version=${version}`,
{
headers: localHeaders,
cache: fetchCache,
},
).then<T | undefined, undefined>(async (res) => {
if (res.ok) return res.json();
await consumeResponseBody(res);

if (res.status === 401) throw new Error(ERRORS.UNAUTHORIZED);
if (res.status === 404) {
// if the x-edge-config-digest header is present, it means
// the edge config exists, but the item does not
if (res.headers.has('x-edge-config-digest')) return undefined;
// if the x-edge-config-digest header is not present, it means
// the edge config itself does not exist
throw new Error(ERRORS.EDGE_CONFIG_NOT_FOUND);
}
if (res.cachedResponseBody !== undefined)
return res.cachedResponseBody as T;
throw new UnexpectedNetworkError(res);
});
},
{ name: 'get', isVerboseTrace: false, attributes: { edgeConfigId } },
),
),
getAll: trace(
async function getAll<T = EdgeConfigItems>(
keys?: (keyof T)[],
localOptions?: EdgeConfigFunctionsOptions,
): Promise<T> {
const localEdgeConfig =
(await getInMemoryEdgeConfig(localOptions)) ||
(await getLocalEdgeConfig(connection, localOptions));

if (localEdgeConfig) {
if (keys === undefined) {
return Promise.resolve(localEdgeConfig.items as T);
has: withIOBoundary(
trace(
async function has(
key,
localOptions?: EdgeConfigFunctionsOptions,
): Promise<boolean> {
const localEdgeConfig =
(await getInMemoryEdgeConfig(localOptions)) ||
(await getLocalEdgeConfig(connection, localOptions));

assertIsKey(key);
if (isEmptyKey(key)) return false;

if (localEdgeConfig) {
return Promise.resolve(
hasOwnProperty(localEdgeConfig.items, key),
);
}

assertIsKeys(keys);
return Promise.resolve(pick(localEdgeConfig.items, keys) as T);
}
const localHeaders = new Headers(headers);
if (localOptions?.consistentRead)
addConsistentReadHeader(localHeaders);

if (Array.isArray(keys)) assertIsKeys(keys);

const search = Array.isArray(keys)
? new URLSearchParams(
keys
.filter((key) => typeof key === 'string' && !isEmptyKey(key))
.map((key) => ['key', key] as [string, string]),
).toString()
: null;

// empty search keys array was given,
// so skip the request and return an empty object
if (search === '') return Promise.resolve({} as T);

const localHeaders = new Headers(headers);
if (localOptions?.consistentRead)
addConsistentReadHeader(localHeaders);

return fetchWithCachedResponse(
`${baseUrl}/items?version=${version}${
search === null ? '' : `&${search}`
}`,
{
// this is a HEAD request anyhow, no need for fetchWithCachedResponse
return fetch(`${baseUrl}/item/${key}?version=${version}`, {
method: 'HEAD',
headers: localHeaders,
cache: fetchCache,
},
).then<T>(async (res) => {
if (res.ok) return res.json();
await consumeResponseBody(res);

if (res.status === 401) throw new Error(ERRORS.UNAUTHORIZED);
// the /items endpoint never returns 404, so if we get a 404
// it means the edge config itself did not exist
if (res.status === 404)
throw new Error(ERRORS.EDGE_CONFIG_NOT_FOUND);
if (res.cachedResponseBody !== undefined)
return res.cachedResponseBody as T;
throw new UnexpectedNetworkError(res);
});
},
{ name: 'getAll', isVerboseTrace: false, attributes: { edgeConfigId } },
}).then((res) => {
if (res.status === 401) throw new Error(ERRORS.UNAUTHORIZED);
if (res.status === 404) {
// if the x-edge-config-digest header is present, it means
// the edge config exists, but the item does not
if (res.headers.has('x-edge-config-digest')) return false;
// if the x-edge-config-digest header is not present, it means
// the edge config itself does not exist
throw new Error(ERRORS.EDGE_CONFIG_NOT_FOUND);
}
if (res.ok) return true;
throw new UnexpectedNetworkError(res);
});
},
{ name: 'has', isVerboseTrace: false, attributes: { edgeConfigId } },
),
),
digest: trace(
async function digest(
localOptions?: EdgeConfigFunctionsOptions,
): Promise<string> {
const localEdgeConfig =
(await getInMemoryEdgeConfig(localOptions)) ||
(await getLocalEdgeConfig(connection, localOptions));

if (localEdgeConfig) {
return Promise.resolve(localEdgeConfig.digest);
}

const localHeaders = new Headers(headers);
if (localOptions?.consistentRead)
addConsistentReadHeader(localHeaders);
getAll: withIOBoundary(
trace(
async function getAll<T = EdgeConfigItems>(
keys?: (keyof T)[],
localOptions?: EdgeConfigFunctionsOptions,
): Promise<T> {
const localEdgeConfig =
(await getInMemoryEdgeConfig(localOptions)) ||
(await getLocalEdgeConfig(connection, localOptions));

if (localEdgeConfig) {
if (keys === undefined) {
return Promise.resolve(localEdgeConfig.items as T);
}

assertIsKeys(keys);
return Promise.resolve(pick(localEdgeConfig.items, keys) as T);
}

return fetchWithCachedResponse(
`${baseUrl}/digest?version=${version}`,
{
headers: localHeaders,
cache: fetchCache,
},
).then(async (res) => {
if (res.ok) return res.json() as Promise<string>;
await consumeResponseBody(res);
if (Array.isArray(keys)) assertIsKeys(keys);

const search = Array.isArray(keys)
? new URLSearchParams(
keys
.filter(
(key) => typeof key === 'string' && !isEmptyKey(key),
)
.map((key) => ['key', key] as [string, string]),
).toString()
: null;

// empty search keys array was given,
// so skip the request and return an empty object
if (search === '') return Promise.resolve({} as T);

const localHeaders = new Headers(headers);
if (localOptions?.consistentRead)
addConsistentReadHeader(localHeaders);

return fetchWithCachedResponse(
`${baseUrl}/items?version=${version}${
search === null ? '' : `&${search}`
}`,
{
headers: localHeaders,
cache: fetchCache,
},
).then<T>(async (res) => {
if (res.ok) return res.json();
await consumeResponseBody(res);

if (res.status === 401) throw new Error(ERRORS.UNAUTHORIZED);
// the /items endpoint never returns 404, so if we get a 404
// it means the edge config itself did not exist
if (res.status === 404)
throw new Error(ERRORS.EDGE_CONFIG_NOT_FOUND);
if (res.cachedResponseBody !== undefined)
return res.cachedResponseBody as T;
throw new UnexpectedNetworkError(res);
});
},
{
name: 'getAll',
isVerboseTrace: false,
attributes: { edgeConfigId },
},
),
),
digest: withIOBoundary(
trace(
async function digest(
localOptions?: EdgeConfigFunctionsOptions,
): Promise<string> {
const localEdgeConfig =
(await getInMemoryEdgeConfig(localOptions)) ||
(await getLocalEdgeConfig(connection, localOptions));

if (localEdgeConfig) {
return Promise.resolve(localEdgeConfig.digest);
}

if (res.cachedResponseBody !== undefined)
return res.cachedResponseBody as string;
throw new UnexpectedNetworkError(res);
});
},
{ name: 'digest', isVerboseTrace: false, attributes: { edgeConfigId } },
const localHeaders = new Headers(headers);
if (localOptions?.consistentRead)
addConsistentReadHeader(localHeaders);

return fetchWithCachedResponse(
`${baseUrl}/digest?version=${version}`,
{
headers: localHeaders,
cache: fetchCache,
},
).then(async (res) => {
if (res.ok) return res.json() as Promise<string>;
await consumeResponseBody(res);

if (res.cachedResponseBody !== undefined)
return res.cachedResponseBody as string;
throw new UnexpectedNetworkError(res);
});
},
{
name: 'digest',
isVerboseTrace: false,
attributes: { edgeConfigId },
},
),
),
};

Expand Down
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