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Docker custom logging driver and Fifo

Hi,
I am trying to create a custom logdriver plugin, for docker and at this point I have a simple plugin working that is able to receive start logging request from docker.
So I run a docker container testserver configured with my log driver plugin-

docker run --log-driver myplugin:v1 -d -p 9000:9000 testserverimg

All is well and I can see that the plugin gets a http call with following body when the logging is started i.e. when the testserver container above runs-

{“File”:"/run/docker/logging/5d25ee773705942a85d81c7eb8a9b304fb0c4cac1b771a12d895a7a6785e54fd",
“Info”:{“ContainerID”:“ae7fee4a50296da201b69d3e980a994eb90b6d9e09575586f24c6b87fc93ec17”,“ContainerName”:"/nifty_curran",“ContainerEntrypoint”:"/usr/bin/testserver",“ContainerArgs”:,"a bunch of other metadata…```

As per my understanding, The “File” key in JSON is the FIFO which needs to be hooked-into by the plugin to read the stdout from the docker container i.e. the testserver.

However I can’t see this fifo file

/run/docker/logging/5d25ee773705942a85d81c7eb8a9b304fb0c4cac1b771a12d895a7a6785e54fd

anywhere on my disk !.. Infact I don’t see a /run/docker/logging directory itself on my host. I am using Docker version 18.09 on Linux Mint.

Any pointers or insights into this would be helpful.
Thanks
Monmohan