Stability: 1 - Experimental
Read-through in-memory cache for S3 objects that are reasonable to cache in memory.
This module offers a read-through in-memory cache for small objects that are stored in S3. It assumes it is running in an environment where aws-sdk has access to its standard credentials chain with s3:GetObject
permission to the configured S3 Bucket.
npm install read-through-s3-memory-cache
npm test
const Cache = require("read-through-s3-memory-cache");
const cache = new Cache(
{
bucket: "name-of-my-s3-bucket"
});
cache.get("myKey", (error, value) =>
{
console.log(error, value);
});
const initialCache = new Map();
initialCache.set("myKey", Buffer.from("myValue"));
const cache2 = new Cache(
{
bucket: "name-of-my-other-s3-bucket",
initialCache
});
cache2.get("myKey", (error, value) =>
{
console.log(error, value);
});
Public API
["AccessDenied", "NoSuchKey"]
Default S3 error codes to treat as "not found" (AccessDenied
can occur if the object does not exist but the caller has no s3:ListBucket
permission).
config
: Object Cache configuration.bucket
: String Name of S3 bucket to retrieve values from.initialCache
: Map (Default: undefined) Initial cached values to use.stdoutTelemetry
: Boolean (Default: false) Iftrue
, telemetry will be emitted tostdout
.
Creates a new Cache.
key
: String S3 Key to retrieve from cache.context
: Object Optional context.parentSpan
: TraceTelemetryEvents.Span Parent span to use to trace execution.
callback
: Functionfunction(error, value){}
error
: Error Error, if any.value
: Buffer S3 Object, if it exists,undefined
otherwise.
Retrieves the cached value
from memory. If not found in memory, attempts to retrieve the value
from S3. If not found in S3, caches undefined
locally, otherwise, caches the value
locally.
We follow the semantic versioning policy (semver.org) with a caveat:
Given a version number MAJOR.MINOR.PATCH, increment the:
MAJOR version when you make incompatible API changes,
MINOR version when you add functionality in a backwards-compatible manner, and
PATCH version when you make backwards-compatible bug fixes.
caveat: Major version zero is a special case indicating development version that may make incompatible API changes without incrementing MAJOR version.