Deploy Spring Boot to a VPS with Maven and Postgres

To deploy Spring Boot to a VPS with ox, add the repo as a project and deploy it, with no Dockerfile and no ox.toml. ox reads pom.xml and mvnw, runs ./mvnw -B -DskipTests package, then starts java -jar target/demo-0.0.1-SNAPSHOT.jar under systemd behind Caddy with HTTPS, and sets up postgres 18 for it. Run ox check in your repo to see the same plan before the first deploy.

Plan verified, real-server test pending. The plan below is what ox check prints for a minimal Spring Boot (Maven) repo in ox's tests. A deploy on a real server is not recorded yet.

What ox detects in a Spring Boot (Maven) repo

This is the plan ox check prints for a minimal a Spring Boot app built with Maven, with no ox.toml. Each row says where its value came from: a file in the repo, or ox's default.

ox check also prints these hints for it:

• the JVM sizes its heap to a quarter of the server's memory: set [app] memory (or [limits] memory) in ox.toml, and ox passes -Xmx at three quarters of it
• Spring Boot reads SPRING_DATASOURCE_URL, not DATABASE_URL: set SPRING_DATASOURCE_URL to jdbc:postgresql://${postgres.host}:${postgres.port}/${postgres.database}, SPRING_DATASOURCE_USERNAME to ${postgres.user} and SPRING_DATASOURCE_PASSWORD to ${postgres.password}

The ox.toml for Spring Boot (Maven)

None is needed: the plan above comes from the repo alone. Write one to serve your own domain or to change what ox detected, and to size the JVM's heap, as the hint says: ox passes -Xmx at three quarters of [app] memory. This one passes ox check against the same repo: [app] keeps the detected start command and build. Once a repo has an ox.toml, ox adds no service itself, so list each one under [services].

domains = ["www.example.com"]

[app]
memory = "1G"

[services]
postgres = {}

Check and deploy Spring Boot (Maven)

Add the repo as a project, then check and ship it from a terminal:

ox check                                # in the repo: the plan above, offline
ox new <owner/repo> --server <server>  # add the repo as a project
ox deploy <project> --wait              # stream the deploy, exit with its result
ox logs <project> --follow             # the app's own logs

Variables to set for Spring Boot (Maven)

None before the first deploy: ox check asks for no variable. Add your own on the dashboard's Variables tab or with ox vars set <project> KEY.

ox provides these to the app itself: PORT, HOST, OX_ENV, OX_PROJECT, OX_RELEASE, OX_DATA_DIR, PUBLIC_URL, PUBLIC_HOST and DATABASE_URL.

If the Spring Boot (Maven) deploy fails

• killed by the out-of-memory killer (the build needs more memory than the project or host allows): The build ran out of memory. Raise the project's memory, add swap, or use a bigger server. More.
• TCP connect to 127.0.0.1:8001 did not answer within 120s: dial tcp 127.0.0.1:8001: connect: connection refused: The app started but never answered on the port ox gave it. Listen on 127.0.0.1 at $PORT; the lines above the message are the app's own output. More.
• Java project found (pom.xml) without Spring Boot or Quarkus: ox does not know how to build and start it; add an ox.toml with [build] commands and [app] start: ox plans Spring Boot and Quarkus. For another Java app, write [build] commands and [app] start. More.

Your visitors never see a failed deploy: the previous release keeps serving until the new one passes its health check.

Next steps

• Set variables and secrets on the dashboard or with ox vars.
• The [app] keys: start, health check, memory and the rest.
• Service dashboards: your database's status, size, backups and data.
• Add a custom domain with one A record; Caddy gets the HTTPS certificate.
• Read the logs live, search them, or download them.
• Set variables and secrets on the dashboard or with ox vars.

Spring Boot (Maven) FAQ

Do I need a Dockerfile or an ox.toml to deploy Spring Boot to a VPS?

No. ox does not use Docker, and ox check on a Spring Boot (Maven) repo with no ox.toml prints Ready to deploy. Write an ox.toml only to change what ox detected.

What does ox install on the server for Spring Boot (Maven)?

Only what the plan names: java temurin-21 (read from pom.xml). Your app's own dependencies are installed by the build into the release folder, not system-wide.

How do I give the JVM more memory?

Set [app] memory in an ox.toml, as the hint above says. ox then passes -Xmx at three quarters of it; without it the JVM takes a quarter of the server's memory.

Related guides

• Spring Boot (Gradle)Deploy a Spring Boot app built with Gradle to your own VPS: ox runs gradlew bootJar, reads the Java version from build.gradle.kts, and runs the jar.
• QuarkusDeploy a Quarkus app to your own VPS in JVM mode: ox builds it with mvnw, runs quarkus-run.jar under systemd, checks /q/health and adds PostgreSQL for it.

Every stack ox deploys, and the ones it does not yet, is on the Stacks page.