ElastiCache

Real Redis, Valkey, and Memcached clusters via Docker. Replication groups, snapshots, ACL user management, configuration endpoints.

fakecloud implements 75 of 75 ElastiCache operations at 100% Smithy conformance. Cache clusters run in real Docker containers — your code connects to a real Redis, Valkey, or Memcached instance.

Supported features

  • Cache clusters — CreateCacheCluster, ModifyCacheCluster, DeleteCacheCluster, DescribeCacheClusters, RebootCacheCluster
  • Real engines via Docker — Redis, Valkey, and Memcached all run as real containers (redis:7-alpine, valkey:8-alpine, memcached:1.6-alpine). All commands work, including streams, pub/sub, Lua, modules, CAS, and the Memcached text/binary protocols
  • Replication groups — CreateReplicationGroup with primary/replica topology (Redis/Valkey only — matches AWS). Persisted fields include AtRestEncryptionEnabled, TransitEncryptionEnabled, TransitEncryptionMode, AuthTokenEnabled, KmsKeyId, LogDeliveryConfigurations, ClusterEnabled, MultiAZ, AutomaticFailover, DataTiering, NetworkType, IpDiscovery, SnapshotRetentionLimit, SnapshotWindow, PreferredMaintenanceWindow, and node-group member topology — all round-tripped through DescribeReplicationGroups
  • Global replication groups — cross-region global datastores (CRUD)
  • Serverless caches — CreateServerlessCache, ModifyServerlessCache (Redis/Valkey only — matches AWS)
  • Snapshots — CreateSnapshot, CopySnapshot, DeleteSnapshot, RestoreReplicationGroupFromSnapshot. Restore reads back the real RDB file dumped during snapshot creation and seeds the replacement Redis/Valkey container with BGSAVE-captured data, so your test fixture's keys survive snapshot/restore round-trips
  • Serverless cache snapshots — CRUD
  • Subnet groups — CRUD
  • Users and user groups — IAM-integrated auth. CreateUser/ModifyUser accept AccessString (RBAC rules) and Passwords/NoPasswordRequired. The container is configured via real Redis ACL SETUSER so the engine enforces the rules — unauthorized commands are rejected by the real engine, not stubbed
  • Parameter groups — CRUD. ModifyCacheParameterGroup parameter changes that map to runtime-tunable Redis options are pushed to the live container via CONFIG SET, so maxmemory-policy, timeout, tcp-keepalive, etc. take effect immediately on the running instance
  • Security groups — cache security group CRUD
  • Failover — TestFailover, TestMigration
  • Tagging — AddTagsToResource, RemoveTagsFromResource, ListTagsForResource
  • Engine versions — DescribeCacheEngineVersions

Configuration endpoint (Memcached)

Memcached cache clusters with NumCacheNodes > 1 expose a real ConfigurationEndpoint in DescribeCacheClusters. The endpoint resolves to a fakecloud-managed config proxy that speaks the Memcached config get cluster command, returning the live node list (host:port pairs) just like AWS's Auto Discovery. The official ElastiCache Cluster Client libraries (elasticache-cluster-client-memcached-for-java, aws-elasticache-cluster-client-libmemcached, etc.) hit the configuration endpoint and discover the real backing nodes without any client-side configuration.

Protocol

Query protocol. Form-encoded body, Action parameter, XML responses.

How the Docker integration works

When you call CreateCacheCluster (or CreateReplicationGroup for Redis/Valkey topologies), fakecloud starts a real Docker container running the corresponding official image and reports the mapped host port. Your application connects with a normal Redis or Memcached client. Memcached gets a real memcached:1.6-alpine container running the full text and binary protocols — not a stub.

Introspection

  • GET /_fakecloud/elasticache/clusters — current cache clusters (id, engine, status, mapped port)
  • GET /_fakecloud/elasticache/replication-groups — replication groups with node members and ports
  • GET /_fakecloud/elasticache/serverless-caches — serverless caches with endpoints
  • GET /_fakecloud/elasticache/acls — ACL state (users + user groups) for replication groups with one or more user groups attached

All four are exposed by the introspection SDKs (fakecloud.elasticache.clusters(), getElastiCacheAcls(), etc.) for assertions in tests.

Gotchas

  • Requires a Docker socket. ElastiCache needs access to /var/run/docker.sock.
  • First use pulls the image. Expect a slower first run while the Redis/Valkey/Memcached image downloads.
  • Memcached is cache-cluster only. AWS does not support replication groups or serverless caches for Memcached, and neither does fakecloud. Use CreateCacheCluster with Engine=memcached.

Source