When using the `file-log` plugin, the output file is not created

After applying the file-log plugin to an API and sending a request, the file defined by config.path is not created. There are no errors in the Kong logs

{
    "created_at": 1584530151,
    "config": {
        "path": "/tmp/konghttp.log",
        "reopen": true
    },
    "id": "58ec6abf-49d9-49f4-901a-f6e74c728700",
    "service": null,
    "name": "file-log",
    "protocols": [
        "grpc",
        "grpcs",
        "http",
        "https"
    ],
    "enabled": true,
    "run_on": "first",
    "consumer": null,
    "route": {
        "id": "5dbafa8c-01fe-42ae-9065-c1628f5c04bc"
    },
    "tags": null
}

For example, the /tmp/konghttp.log file is not created when sending a request to the defined Route

If you are using systemctl to start the Kong service, then the /tmp directory is actually under a private systemd directory in the tmp directory. For example;

/tmp/systemd-private-f3eb59483cee411bb225df3503bc7428-kong-enterprise-edition.service-ars6p8/tmp/konghttp.log

This is the standard behavior of systemd to ensure one process does not overwrite a file from a different process and to avoid any security issues with well known filenames.

If you wish to use a non-private directory, then you will need to change the systemd configuration and specify the PrivateTmp parameter to disable writing to a systemd private directly. Adding a line as below in the .service file to disable the private directory;

PrivateTmp=false

After editing the .service file, make sure to run a systemctl daemon-reload to reload the altered systemd configuration and then restart Kong.