Update NLog ExceptionlessTarget to use Layout for ApiKey and ServerUrl

[snakefoot]

Change these lines:

https://github.com/exceptionless/Exceptionless.Net/blob/17841c9b07858cb3aa5f5f4d5cf038afff5a7bf2/src/Platforms/Exceptionless.NLog/ExceptionlessTarget.cs#L12-L13

To these lines:

 public Layout ApiKey { get; set; } 
 public Layout ServerUrl { get; set; } 

Then update InitializeTarget()

        protected override void InitializeTarget() {
            base.InitializeTarget();

            var apiKey = RenderLogEvent(ApiKey, LogEventInfo.CreateNullEvent());
            var serverUrl = RenderLogEvent(ServerUrl, LogEventInfo.CreateNullEvent());

            if (!String.IsNullOrEmpty(apiKey) || !String.IsNullOrEmpty(serverUrl))
                _client = new ExceptionlessClient(config => {
                    if (!String.IsNullOrEmpty(apiKey) && apiKey != "API_KEY_HERE")
                        config.ApiKey = apiKey;
                    if (!String.IsNullOrEmpty(serverUrl))
                        config.ServerUrl = serverUrl;
                    config.UseInMemoryStorage();
                });
        }

This will enable NLog Target Configuration where settings can be retrieved from app.config or appsettings.json (making it easier to have environment-specific setups)

[niemyjski]

@snakefoot can you provide an example of configuration for this? Also is there a recommended best practice for targets?

[snakefoot]

Yes it is recommended to use NLog Layout for target configuration properties. As you can also see from the link I posted.

See also: https://github.com/NLog/NLog/wiki/How-to-write-a-custom-target

[snakefoot]

Example:

    <target xsi:type="Exceptionless, Exceptionless.NLog" name="exceptionless" apiKey="${configsetting:Exceptionless.ApiKey}">
      <field name="host" layout="${machinename}" />
      <field name="process" layout="${processname}" />
    </target>

Then in appsettings.json (where override can done with ex. appsettings.Production.json):

{
    "Exceptionless":{
        "ApiKey":"API_KEY_HERE"
    }
}

See also: https://github.com/NLog/NLog/wiki/ConfigSetting-Layout-Renderer

P.S. You should update the ReadMe.txt and remove this field from the example-config:

<field name="windows-identity" layout="${windows-identity:userName=True:domain=False}" />

As ${windows-identity} requires additional nuget-package with NLog v5, and not supported on all platforms (Ex. Linux). Maybe consider using ${environment-user} instead.

P.P.S. You should probably remove this rogue nlog.config from your source-repository, since not related to ExceptionLess

[niemyjski]

I guess it wouldn't hurt to support this but I am on the fence with your api key example. Users shouldn't set the api key on an nlog target if it matches the default instance as two exceptionless client instances will be created (when the default should be reused).

@snakefoot thanks for this information, would you mind submitting a pr for all this, it would help out a lot.

[snakefoot]

Created #299

[niemyjski]

Awesome Thanks!, I've left some comments on #299