feat: integrate ContainerDetector for improved container detection in ElastiCache, ECS, and RDS managers

[cfranzen]

Summary

Added ContainerDetector for improved detection if Floci is running inside a container. All services that start up container backends use this detector now.

Type of change

• Bug fix (fix:)
• New feature (feat:)
• Breaking change (feat!: or fix!:)
• Docs / chore

AWS Compatibility

Not requied

Checklist

• ./mvnw test passes locally
• New or updated integration test added
• Commit messages follow Conventional Commits

[Copilot]

Pull request overview

This PR introduces a centralized ContainerDetector to determine whether Floci is running inside a container, and wires that detection into container-backend startup logic (ElastiCache, ECS, RDS) and Docker host resolution.

Changes:

• Added ContainerDetector with multiple heuristics (marker files, env vars, cgroup, mountinfo) and a cached result.
• Updated ElastiCache/ECS/RDS container managers to use ContainerDetector to decide between host port publishing vs using container IPs.
• Moved/updated DockerHostResolver to rely on ContainerDetector, and added unit tests for container detection.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/main/java/io/github/hectorvent/floci/core/common/docker/ContainerDetector.java	New container-runtime detection utility with cached evaluation.
src/test/java/io/github/hectorvent/floci/core/common/docker/ContainerDetectorTest.java	Unit tests covering the detection heuristics and caching behavior.
src/main/java/io/github/hectorvent/floci/core/common/docker/DockerHostResolver.java	Uses ContainerDetector instead of ad-hoc marker/cgroup logic to pick container-to-host address.
src/main/java/io/github/hectorvent/floci/services/elasticache/container/ElastiCacheContainerManager.java	Uses ContainerDetector to choose port binding vs container IP for backend connectivity.
src/main/java/io/github/hectorvent/floci/services/ecs/container/EcsContainerManager.java	Uses ContainerDetector to decide whether to publish ports and how to compute network bindings.
src/main/java/io/github/hectorvent/floci/services/rds/container/RdsContainerManager.java	Uses ContainerDetector to choose port binding vs container IP for backend connectivity.
src/main/java/io/github/hectorvent/floci/services/lambda/launcher/ContainerLauncher.java	Updates import to the new DockerHostResolver package.

Comments suppressed due to low confidence (3)

src/main/java/io/github/hectorvent/floci/services/elasticache/container/ElastiCacheContainerManager.java:171

• When a user configures dockerNetwork/networkMode as host, Docker rejects containers that also specify port bindings ("conflicting options: port publishing and the container type network mode"). With the new !containerDetector.isRunningInContainer() condition, port bindings are now added for all host runs, which can break the previously-working networkMode=host setup on native Linux. Consider skipping port bindings when the configured network mode is host (and other incompatible modes), or compute the bind/inspect strategy after resolving the effective network mode instead of basing it solely on isRunningInContainer().

    private HostConfig buildHostConfig() {
        HostConfig hostConfig = HostConfig.newHostConfig();
        if (!containerDetector.isRunningInContainer()) {
            // Bind BACKEND_PORT → random host port so the JVM can reach the container
            int freePort = findFreePort();
            Ports portBindings = new Ports();
            portBindings.bind(ExposedPort.tcp(BACKEND_PORT), Ports.Binding.bindPort(freePort));
            hostConfig.withPortBindings(portBindings);
            LOG.debugv("Native mode: binding container port 6379 → host port {0}", freePort);

src/main/java/io/github/hectorvent/floci/services/rds/container/RdsContainerManager.java:174

• Same issue as ElastiCache: if dockerNetwork/networkMode is set to host, Docker does not allow port bindings. Since port bindings are now applied whenever Floci is not running in a container, starting an RDS backend with networkMode=host can fail on native Linux. Please gate port-binding logic on the effective network mode (skip for host/other incompatible modes) rather than only on isRunningInContainer().

    private HostConfig buildHostConfig(int enginePort) {
        HostConfig hostConfig = HostConfig.newHostConfig();
        if (!containerDetector.isRunningInContainer()) {
            int freePort = findFreePort();
            Ports portBindings = new Ports();
            portBindings.bind(ExposedPort.tcp(enginePort), Ports.Binding.bindPort(freePort));
            hostConfig.withPortBindings(portBindings);
            LOG.debugv("Native mode: binding container port {0} → host port {1}", enginePort, freePort);
        }

src/main/java/io/github/hectorvent/floci/services/ecs/container/EcsContainerManager.java:183

• Port bindings are applied whenever Floci is not running in a container, but Docker forbids publishing ports when HostConfig.networkMode is host. Since the ECS container network mode can be set via config, this can make task startup fail for dockerNetwork=host on native Linux. Consider determining the effective network mode first and skipping withPortBindings(...) when it is host (or other incompatible modes).

    private HostConfig buildHostConfig(ContainerDefinition def, List<ExposedPort> exposedPorts) {
        HostConfig hostConfig = HostConfig.newHostConfig();

        if (def.getMemory() != null) {
            hostConfig.withMemory((long) def.getMemory() * 1024 * 1024);
        }

        if (!containerDetector.isRunningInContainer() && !exposedPorts.isEmpty()) {
            Ports portBindings = new Ports();
            for (ExposedPort ep : exposedPorts) {
                portBindings.bind(ep, Ports.Binding.bindPort(0)); // 0 = dynamic host port
            }
            hostConfig.withPortBindings(portBindings);
        }

[hectorvent]

Thanks @cfranzen

[hectorvent]

@cfranzen conflicts need to be resolved

[cfranzen]

@hectorvent just resolved it a minute ago