splunk-url incorrect validation error

[tripptuttle]

What happened: When trying to start a container, I get this error:

Error response from daemon: failed to create task for container: failed to initialize logging driver: splunk: expected format scheme://dns_name_or_ip:port for splunk-url\n

What you expected to happen: The daemon to start and logs to be sent to splunk. Our HEC endpoint is https://http-inputs-XXXX.splunkcloud.com/services/collector, from which I removed the /services/collector as the plugin requests. I've even tried adding in the :443 port to the name to see if that gets past the url validation. But your own plugin instructions state that no port should be provided

I can send logs in no problem using a curl command to https://http-inputs-XXXX.splunkcloud.com/services/collector or https://http-inputs.XXX.splunkcloud.com/services/collector

My theory is the plugin is validating the URL provided in daemon.json incorrectly.

How to reproduce it (as minimally and precisely as possible):

1. Setup /etc/docker/daemon.json as follows:

   {
   "data-root": "/opt/orbs/docker",
   "bip": "172.17.1.1/24",
   "log-driver": "splunk-logging-plugin",
   "log-opts": {
   "splunk-url": "https://http-inputs-XXXX.splunkcloud.com/",
   "splunk-token": "<TOKEN>",
   "splunk-insecureskipverify": "true"
   }
   }

2. Restart docker daemon and run docker compose up on a valid Docker Compose file
3. Error should happen

Anything else we need to know?:

I have the exact same issue with the built in docker splunk driver AND this splunk docker plugin.

Environment:

• Docker version (use docker version):

  
  Client: Docker Engine - Community
  Version:           26.1.2
  API version:       1.45
  Go version:        go1.21.10
  Git commit:        211e74b
  Built:             Wed May  8 14:01:38 2024
  OS/Arch:           linux/amd64
  Context:           default

Server: Docker Engine - Community Engine: Version: 26.1.3 API version: 1.45 (minimum version 1.24) Go version: go1.21.10 Git commit: 8e96db1 Built: Thu May 16 08:33:39 2024 OS/Arch: linux/amd64 Experimental: false containerd: Version: 1.6.31 GitCommit: e377cd56a71523140ca6ae87e30244719194a521 runc: Version: 1.1.12 GitCommit: v1.1.12-0-g51d5e94 docker-init: Version: 0.19.0 GitCommit: de40ad0

- OS (e.g: `cat /etc/os-release`):

NAME="Red Hat Enterprise Linux" VERSION="9.3 (Plow)"

- Splunk version:
``` cloud ```
- Others:

[tripptuttle]

We got Splunk logging working with the built-in docker driver instead of this plugin, so closing this issue.