How to find OS level pid of a running java app in diego_cell

Products

• VMware Tanzu Application Service for VMs

Issue/Introduction

Sometimes an operator may want to run specific commands, such as strace, for the app process outside of the container. 

The following instructions can be used to get the pid for a java application. 

1. Run this command: cf app <app_name> --guid . It shows the app_guid.

2. Run this command: cf curl /v2/apps/<app_guid>/stats or cf curl /v3/processes/<app_guid>/stats . It shows the host IP address and port of the Diego cell in which the app instance is running.

3. Run the command bosh vms | grep <host>  to retrieve the diego_cell name where host is the IP address listed in step 2.

4. Run this command bosh -d <cf-deployment> ssh <diego_cell> to SSH into the Diego cell to login.

5. Run cfdot actual-lrps | grep <host> | grep <app_guid> | jq '.instance_guid' 

     or  cfdot actual-lrps | grep <host> | grep <port>  | jq '.instance_guid'

     It shows the instance_guid, which is the app container guid.

Note: If you do not see any output from the above command, refer to Alternate method to locate an app instance_guid in VMware Tanzu Application Service (TAS) for VMs for information how to locate the instance_guid with a different method.

6. Run ps axjfww | grep <instance_guid> -C 1 | grep [j]ava. The 2nd, 3rd and 4th columns show the app OS pid. 

Note: the brackets '[]' around the character 'j' in "java" prevents an extra undesired line in the output.

diego_cell/660729bc-6c0a-4bee-91f8-cf1aedd6a71a:~$ ps axjfww | grep 92c8482b-c806-4de0-6e39-77dc -C 1 | grep [j]ava
2047566 2047698 2047698 2047698 ?             -1 Ssl   2000   3:19  |   \_ /home/vcap/app/.java-buildpack/open_jdk_jre/bin/java -agentpath:/home/vcap/app/.java-buildpack/open_jdk_jre/bin/jvmkill-1.17.0_RELEASE=printHeapHistogram=1 -Djava.io.tmpdir=/home/vcap/tmp -XX:ActiveProcessorCount=4 -Djava.ext.dirs= -Djava.security.properties=/home/vcap/app/.java-buildpack/java_security/java.security -Xmx411542K -Xss1M -XX:ReservedCodeCacheSize=240M -XX:MaxDirectMemorySize=10M -XX:MaxMetaspaceSize=125033K -cp /home/vcap/app/.:/home/vcap/app/.java-buildpack/container_security_provider/container_security_provider-1.19.0_RELEASE.jar org.springframework.boot.loader.JarLauncher

In the example above, the OS pid is 2047698.

 

Resolution

In the example above, the OS pid is 2047698.