# Spring Boot

> Monitor a Spring Boot service: Tomcat's access log with status, Spring Security events for sign-ins, and beam monitor with the Spring and Java rules, actuators included.

Source: https://docs.agentbeam.com/cookbooks/frameworks/spring-boot

## How Beam reads a Spring Boot app

There's no in-process SDK for this stack, so the app writes what Beam needs to its logs and [`beam monitor`](https://docs.agentbeam.com/agent-cli/app-monitoring#install-and-start) reads them on the same server or container. Only redacted findings leave it. Two kinds of line:

- **One JSON line per request**, with `method`, `path` (with the query string), `status`, `ip`, `user_agent`, `host` and `duration_ms`. The status is what lets Beam tell an attack your app refused from one it answered.
- **Security events as plain lines**, worded like this (Beam matches the wording and reads `user=` and `ip=`):

```text
login failed user=42 ip=203.0.113.7
login succeeded user=42 ip=203.0.113.7
granted admin role to user=99 by user=12
API key created user=12
{"event":"llm_usage","user":"42","model":"gpt-5","total_tokens":1834}
```

Use an opaque user id, never an email. New outbound hosts are only reported by the Node.js SDK; for this stack, restrict outbound traffic at the network instead.

Spring Boot's embedded Tomcat can write the request log in the combined format Beam reads, so you don't need a JSON line for requests.

## Before you start

Do steps 1 and 2 of the [general cookbook](https://docs.agentbeam.com/cookbooks/app-monitoring#step-1-turn-it-on-and-create-the-apps-token) first: App monitoring is on, the app is added, and its `beam_app_` token is in your secret store as `BEAM_APP_TOKEN`. Everything below needs `@agent-beam/beam` 0.2.32 or newer.

## Turn on Tomcat's access log

```properties
# application.properties
server.tomcat.accesslog.enabled=true
server.tomcat.accesslog.directory=/var/log/app
server.tomcat.accesslog.prefix=access
server.tomcat.accesslog.suffix=.log
server.tomcat.accesslog.rotate=false
server.tomcat.accesslog.pattern=combined
# Behind a load balancer: log the client, not the proxy
server.forward-headers-strategy=native
server.tomcat.remoteip.remote-ip-header=x-forwarded-for
```

Rotate the file with logrotate; `beam monitor` follows rotation.

## Log sign-ins, admins and keys

```java
// BeamSecurityEvents.java
@Component
public class BeamSecurityEvents {
    private static final Logger log = LoggerFactory.getLogger("beam.security");

    @EventListener
    public void onSuccess(AuthenticationSuccessEvent event) {
        log.info("login succeeded user={} ip={}", userId(event.getAuthentication()), ip(event.getAuthentication()));
    }

    @EventListener
    public void onFailure(AbstractAuthenticationFailureEvent event) {
        log.warn("login failed user={} ip={}", userIdForName(event.getAuthentication().getName()), ip(event.getAuthentication()));
    }

    private static String ip(Authentication auth) {
        return auth.getDetails() instanceof WebAuthenticationDetails d ? d.getRemoteAddress() : "";
    }
}
```

Send the `beam.security` logger to its own file with a message-only pattern (`%msg%n`) in `logback-spring.xml`. Where you grant roles or issue keys, log `granted admin role to user={} by user={}` and `API key created user={}`.

## Run `beam monitor` next to the app

```sh
npm install -g @agent-beam/beam
beam monitor --stack spring --file /var/log/app/access.log --file /var/log/app/security.log --app /srv/app
```

`--stack spring` turns on this framework's rules and rolls up attacks on frameworks you don't run; `--app` also checks the app's lockfiles daily (and would detect the stack on its own). Keep it running with systemd:

```ini
# /etc/systemd/system/beam-monitor.service
[Unit]
Description=AgentBeam App monitoring
After=network-online.target

[Service]
EnvironmentFile=/etc/beam/app.env
ExecStart=/usr/bin/env beam monitor --stack spring --file /var/log/app/access.log --file /var/log/app/security.log --app /srv/app
Restart=always
User=beam

[Install]
WantedBy=multi-user.target
```

```sh
sudo install -m 600 /dev/null /etc/beam/app.env && echo "BEAM_APP_TOKEN=beam_app_..." | sudo tee /etc/beam/app.env >/dev/null
sudo systemctl daemon-reload && sudo systemctl enable --now beam-monitor
```

In Docker or Kubernetes, run the same command in a sidecar that mounts the log directory read-only, with `BEAM_APP_TOKEN` from a secret.
## Prove it works

```sh
beam monitor status   # app, level, stack, usage
beam monitor test     # a test finding through your alert workflows
curl -s "https://your-app.example.com/?id=1%20UNION%20SELECT%201" -o /dev/null
```

Within a minute, the SQL injection test shows on **App monitoring**: under **Needs action** if the app answered 2xx, or counted under "needed nothing from you" if it refused it. Then sign in to a test account with a wrong password ten times and the right one once: **Sign-in succeeded after 10 failed attempts** appears as critical.
## Check dependencies on every pull request

```yaml
# .github/workflows/beam-cve.yml
name: Dependency check
on: [pull_request]
jobs:
  cve:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - run: npx -y @agent-beam/beam cve check . --fail-on high
        env:
          BEAM_APP_TOKEN: ${{ secrets.BEAM_APP_TOKEN }}
```

Lockfiles are what's checked: use Gradle dependency locking (`gradle.lockfile`). Maven `pom.xml` versions aren't checked.
## What Beam watches for on this stack

Besides every [built-in rule](https://docs.agentbeam.com/agent-cli/app-monitoring#levels-and-detection) and the [attack-in-progress signals](https://docs.agentbeam.com/agent-cli/app-monitoring#signs-an-attack-is-underway):

| Rule | Means | Severity |
| --- | --- | --- |
| Spring4Shell | `class.module.classLoader` in a request (CVE-2022-22965) | Critical |
| Java expression injection | SpEL (`T(java.lang.Runtime)`) or OGNL payloads, in requests or logs | Critical |
| Spring Boot actuator served | `/actuator/env`, `heapdump`, `threaddump`, `configprops`, `gateway/routes` and others answered 2xx | Critical |
| Java admin console served | Tomcat manager, Jolokia or JMX consoles answered 2xx | High |
| Log4Shell | `${jndi:` lookups, including obfuscated ones | Critical |

Attacks on other frameworks (WordPress probes, Laravel or Spring exploits, and so on) are rolled up as **Not your stack** when there's no status to say otherwise, and never alert.
## Close what Beam would catch

Beam raises these when they're found; better that there's nothing to find:

- Expose only `health` and `info`: `management.endpoints.web.exposure.include=health,info`, ideally on a separate `management.server.port` not reachable from the internet.
- Keep Spring Boot and Spring Framework on supported, patched versions.
- Don't deploy the Tomcat manager app.
## Coverage checklist

| Feature | Done when |
| --- | --- |
| Request log with status | Findings show **Answered**, **Refused** or **Errored** |
| Stack declared | `beam monitor` prints the stack at start |
| Sign-in events | `login failed` and `login succeeded` lines are written |
| Admin and key events | Role grants and new keys are logged |
| LLM spend | An `llm_usage` line follows each model call |
| Dependency checks | The CI job runs on pull requests |
| Alerts | Critical pages someone, high reaches a channel ([step 8](https://docs.agentbeam.com/cookbooks/app-monitoring#step-8-send-alerts-to-the-right-place)) |
| Routine | Someone reads **Needs action** daily and **Attack analytics** weekly |