cachelet

A small in-memory key/value cache service with per-entry TTL, exposed over HTTP.

It is intentionally minimal: a single-process cache with lazy expiry on read and a background janitor that periodically evicts expired entries.

Scope and limitations

cachelet is deliberately small. Known non-goals in the current version:

• Unbounded entry count. Eviction is by TTL only — there is no maximum size and no LRU policy. Entries written without a TTL live until explicitly deleted, so the store can grow without bound. It is a TTL cache, not a bounded LRU.
• Single process, in-memory. No persistence and no replication.
• 1 MiB per-entry limit. PUT bodies larger than 1 MiB are rejected.

Layout

.
├── cmd/cachelet/
│   └── main.go        # process entrypoint: HTTP server + graceful shutdown
├── cache/             # the cache.Store (TTL map, janitor)
│   ├── store.go
│   └── store_test.go
└── server/            # HTTP layer over a cache.Store
    ├── handler.go     # apiHandler adapter + middleware chain
    ├── middleware.go  # logRequests (request observability)
    ├── server.go      # routes and handlers
    └── server_test.go

Build, test, run

make build      # compile ./...
make test       # go test ./...
make race       # go test -race ./...
make vet        # go vet ./...

go run ./cmd/cachelet   # start the server (CACHELET_ADDR, default :8080)

API

Method	Path	Body	Description
GET	/cache/{key}	—	Returns the value as text/plain, or 404 if absent.
PUT	/cache/{key}	value	Stores the body. Optional ?ttl=<seconds> sets expiry. 204 on success.
DELETE	/cache/{key}	—	Removes the key. Always 204.
GET	/stats	—	{"entries":<n>}.

Examples

curl -X PUT --data 'hello' 'localhost:8080/cache/greeting?ttl=30'
curl localhost:8080/cache/greeting          # -> hello
curl -i localhost:8080/cache/missing        # -> 404
curl localhost:8080/stats                    # -> {"entries":1}