Tracker Checker: handle HTTP Tracker error ConnectionRefused

[josecelano]

Parent issue: #669
Depends on: #680

When you run the Tracker Checker with a HTTP Tracker service not running you get this error:

TORRUST_CHECKER_CONFIG='{
    "udp_trackers": [],
    "http_trackers": ["http://127.0.0.1:7070"],
    "health_checks": []
}' cargo run --bin tracker_checker

Running checks for trackers ...
UDP trackers ...
HTTP trackers ...
thread 'main' panicked at /home/josecelano/Documents/git/committer/me/github/torrust/torrust-tracker/src/shared/bit_torrent/tracker/http/client/mod.rs:87:61:
called `Result::unwrap()` on an `Err` value: reqwest::Error { kind: Request, url: Url { scheme: "http", cannot_be_a_base: false, username: "", password: None, host: Some(Ipv4(127.0.0.1)), port: Some(7070), path: "/announce", query: Some("info_hash=%9C8B%22%13%E3%0B%FF%21%2B0%C3%60%D2o%9A%02%13d%22&peer_addr=192.168.1.88&downloaded=0&uploaded=0&peer_id=%2DqB00000000000000001&port=17548&left=0&event=completed&compact=0"), fragment: None }, source: hyper::Error(Connect, ConnectError("tcp connect error", Os { code: 111, kind: ConnectionRefused, message: "Connection refused" })) }
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

After implementing the issue #680 we could catch the error and continue with the execution of the Tracker Checker, checking other services. CUrrently, the checker is halted without finishing.

[josecelano]

This was implemented by @da2ce7.

The current output is you disable only the HTTP tracker:

$ TORRUST_CHECKER_CONFIG='{
    "udp_trackers": ["127.0.0.1:6969"],
    "http_trackers": ["http://127.0.0.1:7070"],
    "health_checks": []
}' cargo run --bin tracker_checker
    Finished `dev` profile [optimized + debuginfo] target(s) in 0.09s
     Running `target/debug/tracker_checker`
2024-09-11T15:44:27.049057Z  INFO torrust_tracker::console::clients::checker::service: Running checks for trackers ...
[
  {
    "Udp": {
      "Ok": {
        "remote_addr": "127.0.0.1:6969",
        "results": [
          [
            "Setup",
            {
              "Ok": null
            }
          ],
          [
            "Connect",
            {
              "Ok": null
            }
          ],
          [
            "Announce",
            {
              "Ok": null
            }
          ],
          [
            "Scrape",
            {
              "Ok": null
            }
          ]
        ]
      }
    }
  },
  {
    "Http": {
      "Err": {
        "url": "http://127.0.0.1:7070/",
        "results": [
          [
            "Announce",
            {
              "Err": "Http request did not receive a response within the timeout: ResponseError { err: reqwest::Error { kind: Request, url: \"http://127.0.0.1:7070/announce?info_hash=%9C8B%22%13%E3%0B%FF%21%2B0%C3%60%D2o%9A%02%13d%22&peer_addr=192.168.1.88&downloaded=0&uploaded=0&peer_id=%2DqB00000000000000001&port=17548&left=0&event=completed&compact=0\", source: hyper_util::client::legacy::Error(Connect, ConnectError(\"tcp connect error\", Os { code: 111, kind: ConnectionRefused, message: \"Connection refused\" })) } }"
            }
          ],
          [
            "Scrape",
            {
              "Err": "Http request did not receive a response within the timeout: ResponseError { err: reqwest::Error { kind: Request, url: \"http://127.0.0.1:7070/scrape?info_hash=%9C8B%22%13%E3%0B%FF%21%2B0%C3%60%D2o%9A%02%13d%22\", source: hyper_util::client::legacy::Error(Connect, ConnectError(\"tcp connect error\", Os { code: 111, kind: ConnectionRefused, message: \"Connection refused\" })) } }"
            }
          ]
        ]
      }
    }
  }
]

The checks for the UDP are executed correctly.