Neo4jContainer

A single-node Neo4j Community container, queried over its HTTP Cypher transaction endpoint (/db/neo4j/tx/commit) — no bolt driver dependency needed, matching the house convention for HTTP-first modules (ClickHouse, Pinot). The bolt port (7687) is still exposed and its URI available via bolt_url() for callers who do want a real driver.

Default image: floats to neo4j:latest — this module previously pinned neo4j:5-community. Guest ports: 7474 (HTTP), 7687 (bolt) Expected repository: neo4j

Method	On	Effect
`Neo4jContainer::new()`	builder	Floating default image, `neo4j`/`rightsize-test`, `with_memory_limit(1024)`.
`Neo4jContainer::with_image(image)`	builder	Caller-chosen image, kept verbatim.
`.with_password(p)`	builder	Overrides the password half before `start()` (the image requires ≥8 characters).
`.start()`	builder → `Result<Neo4jGuard>`	Checks the image’s repository, then boots the container.
`.username()`	guard	The fixed admin username (`neo4j` — no env var to change it).
`.password()`	guard	The configured admin password.
`.http_url()`	guard	The HTTP interface’s base URI — Cypher transactions via `POST {http_url}/db/neo4j/tx/commit`.
`.bolt_url()`	guard	The bolt interface’s URI, for callers using a real bolt driver.
`.stop()`	guard	Stops and removes the container, releases its ports.

Compatibility checking

with_image takes impl Into<ImageName> and keeps the image verbatim. start() then checks that image’s repository (registry host, tag, and digest stripped) against neo4j before any backend is resolved or any sandbox is created, which keeps the constructors infallible like every other module’s. A mismatch returns RightsizeError::IncompatibleImage; ImageName::parse(image) .as_compatible_substitute_for("neo4j") is the escape hatch for a verified drop-in replacement from another registry. new() goes through this same check against its own floating reference, so it can never fail in practice.

There’s no with_username — the username is fixed by the image at neo4j.

Readiness — `Started.` is the exact log line, verified against a real boot

Captured verbatim from neo4j:5-community:

... INFO  Bolt enabled on 0.0.0.0:7687.
... INFO  HTTP enabled on 0.0.0.0:7474.
... INFO  Remote interface available at http://localhost:7474/
... INFO  Started.

Started. is logged only after both connectors are already listening, so it’s both accurate and simpler than a two-port HTTP/bolt race.

Ships as .*Started\..* — a real regex, so the escaped dot means exactly what it reads: a literal . right after “Started”, not a wildcard.

The image refuses short passwords

neo4j/neo4j is rejected at boot — passwords must be at least 8 characters — so this module defaults to neo4j/rightsize-test, giving zero-configuration use of http_url() plus basic auth. with_password still requires an 8+-character value.

Memory — measured, needed the ladder

At msb’s default ~450 MB microVM RAM, the server logs ERROR Invalid memory configuration - exceeds physical memory and shuts itself down cleanly (INFO Stopped.) rather than hanging or getting OOM-killed — Neo4j’s own memory-recommendation calculator sizes the page cache and heap off total visible RAM and refuses to start if the sums don’t fit. Retried with -m 1024M: boots clean. with_memory_limit(1024) is this module’s default, same number as KeycloakContainer.

Complete example

use rightsize_modules::Neo4jContainer;

#[tokio::test]
async fn create_then_match_round_trips() -> Result<(), Box<dyn std::error::Error>> {
    let guard = Neo4jContainer::new().start().await?;

    let agent = ureq::Agent::new_with_defaults();
    let auth = format!("Basic {}", "bmVvNGo6cmlnaHRzaXplLXRlc3Q"); // base64 in the real test
    let commit_url = format!("{}/db/neo4j/tx/commit", guard.http_url());
    let commit = |statement: &str| {
        let body = format!(r#"{{"statements":[{{"statement":"{statement}"}}]}}"#);
        agent
            .post(&commit_url)
            .header("Content-Type", "application/json")
            .header("Authorization", &auth)
            .send(body)
    };

    let mut create = commit("CREATE (n:Test {name: 'hello'}) RETURN n.name AS name")?;
    let create_body = create.body_mut().read_to_string()?;
    assert!(create_body.contains("\"errors\":[]"));

    let mut matched = commit("MATCH (n:Test {name: 'hello'}) RETURN n.name AS name")?;
    let match_body = matched.body_mut().read_to_string()?;
    assert!(match_body.contains("\"hello\""));

    guard.stop().await?;
    Ok(())
}

Backend notes

with_memory_limit(1024) is set unconditionally by the module — see Memory above.

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