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 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=):

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 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

# 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

// 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

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:

# /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

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

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

# .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 and the attack-in-progress signals:

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