Memcached

dev.rightsize.modules.MemcachedContainer — a single-node Memcached container, ready-checked with a protocol-level version probe rather than a bare port check.

Defaults

Default image	memcached:latest — this image's floating reference (see below)
Exposed port	11211
Wait strategy	Custom (MemcachedResponds, see below)

With no image given, this module tracks upstream's latest tag rather than a version this library pins. This module previously pinned memcached:1.6-alpine; latest is the Debian-based variant, not Alpine — functionally equivalent for the version probe below, just a larger pull. Pass an explicit tag (Alpine or otherwise) to pin a specific version:

MemcachedContainer("memcached:1.6-alpine")

Helpers

Member	Returns
address: String	The host:port address of the running container

Example

package dev.rightsize.modules

import dev.rightsize.modules.MemcachedContainer
import org.junit.jupiter.api.Assertions.assertTrue
import org.junit.jupiter.api.Test
import java.net.Socket

class MemcachedContainerTest {
    @Test
    fun `responds to a version request`() {
        val mc = MemcachedContainer()
        mc.start()
        try {
            Socket("127.0.0.1", mc.getMappedPort(11211)).use { s ->
                s.getOutputStream().write("version\r\n".toByteArray())
                val line = s.getInputStream().bufferedReader().readLine()
                assertTrue(line.startsWith("VERSION"))
            }
        } finally {
            mc.stop()
        }
    }
}

Backend notes

Memcached logs nothing on startup, and the userland proxy on either backend can bind the host port and start accepting connections before the server inside is actually serving requests — so a bare Wait.forListeningPort() isn't reliable here. This module's wait strategy instead sends the memcached text-protocol version command and waits for a VERSION-prefixed reply, which only a fully-initialized server produces. See Wait Strategies for the full source of MemcachedResponds, which is a good template if you're writing a wait strategy of your own for a text-protocol server.

Compatibility checking

Passing an explicit image checks its repository against the one this module understands (memcached) before any port, wait-strategy, or backend work runs — a mismatched image fails fast with a typed IncompatibleImageException naming both repositories, rather than degrading into a bare wait-strategy timeout. To use a differently-named image on purpose (a private mirror, a hardened rebuild), wrap it with the escape hatch:

MemcachedContainer(
    DockerImageName.parse("mycorp/memcached-hardened:1.6")
        .asCompatibleSubstituteFor("memcached"))

See Core Concepts for DockerImageName itself.