/dev/stdout permission denied Tomcat access logs - spring-boot

Question

I'm trying to enable Tomcat access logs in the STS console, but i get an error on startup:
java.io.FileNotFoundException: /dev/stdout.2020-09-02 (Permission denied)
at java.io.FileOutputStream.open0(Native Method)
at java.io.FileOutputStream.open(FileOutputStream.java:270)
at java.io.FileOutputStream.<init>(FileOutputStream.java:213)
at org.apache.catalina.valves.AccessLogValve.open(AccessLogValve.java:585)
at org.apache.catalina.valves.AccessLogValve.startInternal(AccessLogValve.java:615)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
at org.apache.catalina.core.StandardPipeline.startInternal(StandardPipeline.java:182)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:953)
at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:262)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
at org.apache.catalina.core.StandardService.startInternal(StandardService.java:422)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:793)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
at org.apache.catalina.startup.Tomcat.start(Tomcat.java:344)
at org.springframework.boot.context.embedded.tomcat.TomcatEmbeddedServletContainer.initialize(TomcatEmbeddedServletContainer.java:99)
at org.springframework.boot.context.embedded.tomcat.TomcatEmbeddedServletContainer.<init>(TomcatEmbeddedServletContainer.java:84)
at org.springframework.boot.context.embedded.tomcat.TomcatEmbeddedServletContainerFactory.getTomcatEmbeddedServletContainer(TomcatEmbeddedServletContainerFactory.java:552)
at org.springframework.boot.context.embedded.tomcat.TomcatEmbeddedServletContainerFactory.getEmbeddedServletContainer(TomcatEmbeddedServletContainerFactory.java:177)
at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.createEmbeddedServletContainer(EmbeddedWebApplicationContext.java:164)
at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.onRefresh(EmbeddedWebApplicationContext.java:134)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:537)
at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh(EmbeddedWebApplicationContext.java:122)
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:762)
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:372)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:316)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1187)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1176)
at au.com.paycorp.rest.ws.Application.main(Application.java:29)
application.yml :
server:
port: 50110
contextPath: /rest
tomcat:
accesslog:
enabled: true
directory: "/dev"
prefix: stdout
buffered: false
suffix:
file-date-format:
pattern: "[ACCESS] %{org.apache.catalina.AccessLog.RemoteAddr}r %l %t %D %F %B %S vcap_request_id:%{X-Vcap-Request-Id}i"
I understand that it does not have the permission to write to /dev/stdout, but i'm not sure how to whitelist it, how to give it permission for access.

Answer 1

I would say that you issue is not in your code but on your server.
Obviously, it's Linux or Unix. So, use a chmod command to change what your user can do on this folder.

Answer 2

Give ownership of the dev folder to the current user with:
sudo chown -R $USER dev/
Change the group owner of the folder to the current user using this command:
sudo chgrp -R $USER dev/
This should fix it.

Answer 3

As you can see, Tomcat is trying to open the file /dev/stdout.2020-09-02 instead of /dev/stdout. The reason behind this is that an empty file-data-format means default format for your locale. If you want to disable the addition of a date in the filename you need to use:
rotatable: false
On the other hand this will redirect your logs to the standard output depending on whether the standard output is a file or not: Java does not duplicate the file descriptor 1, but calls open on /dev/stdout. Check this answer to understand why it won't work on pipes/sockets.
To achieve what you want you'll need to modify the method AccessLogValve#open:
protected synchronized void open() {
// Open the current log file
// If no rotate - no need for dateStamp in fileName
File pathname = getLogFile(rotatable && !renameOnRotate);
// Modify HERE:
if ("-".equals(pathname)) {
writer = System.out;
return;
}
...
}
and set - as the name of your logfile.