Starting Spring Boot as a foreground process from within a bash script

Question

I package my Spring Boot war with embedded Tomcat servlet container. And deploy it as a regular java application using java -jar server.war <Spring Args>. I wrote a bash script that would take care of deploying the server as a background/foreground process:

start_foreground() {
    cmd="$JAVACMD ${JVM_OPTS} -jar ${WAR_FILE} ${SPRING_OPTS}"
    echo "\"${cmd}\""
    eval ${cmd}
    print_log "Server is stopped."
}

start_background() {
    SPRING_OPTS="--spring.pid.file=${PID_FILE} ${SPRING_OPTS}"
    cmd="nohup $JAVACMD ${JVM_OPTS} -jar ${WAR_FILE} ${SPRING_OPTS} &>${LOG_PATH}/console.log &"
    echo "\"${cmd}\""
    eval ${cmd}
    PID=$!
    print_log "Server is started with pid \"${PID}\""
}

As you can see, for background process start I use nohup. Everything is working fine, it sends STDOUT and STDERR to my ${LOG_PATH}/console.log. console.log reports that my server is up and running on preconfigured port (using Spring profiles). I have a profile dev-https that configured with port 8443:

spring:
  profiles.active: dev-https
...
---

spring:
    profiles: dev-https
server:
  port: 8443
  ssl:
    enabled: true
    protocol: TLS
    enabled-protocols: TLSv1.2
    key-store: <path>
    key-store-password: <password>

However, when I try to start the server as a foreground process, I get unexpected behavior. Whenever I deploy the server using start_foreground(), it starts fine, but the port resets to default 8080.

If I attach a debugger, and try to get values using environment.getProperty("server.port"), it will return empty string (however, if a property is not defined, it usually returns null). Moreover, all other properties return expected values:

environment.getProperty("spring.profiles.active")=dev-https

environment.getProperty("server.ssl.enabled")=true

etc.

I tried to replace eval with exec and even run ${cmd} by itself inside start_foreground() bash function, but the port always resets to 8080, and server.port returns empty string.

The weirdest part is that if I execute ${cmd} in my console (not from within the script), everything works flawlessly (right profile, and right port get used).

Has anyone encountered such weird problem?

Answer 1

It looks like you are using the configuration(like port number etc... only for background and not used for foreground. You have not declared the variable (you missed this line)

`SPRING_OPTS="--spring.pid.file=${PID_FILE} ${SPRING_OPTS}"` 

for foreground.

Answer 2

I tried to reproduce this problem with a new instance of Spring Boot. Wrote a quick bash script, and everything went fine!

Then, I started playing around with my original script, and found out that I was using SERVER_PORT variable (because I had an optional argument --port <num> for the user).

Apparently, this environment variable is also used by Spring Framework: https://www.concretepage.com/spring-boot/spring-boot-change-default-server-port#server_port

My mistake was exporting SERVER_PORT var (however, I needed it for other reasons).

Solution would be to either remove export from export SERVER_PORT="" or rename variable to something else (which I ended up doing).