Adding resource tags dinamically after initialization

Question

First of all, congratulations on the awesome work!

On OpenTelemetry initialization we do something similar to the following:

var resource = Resources.CreateServiceResource(conf.ServiceName, serviceVersion: conf.ServiceVersion)
 .Merge(new Resource(new Dictionary<string, object>
 {
    {"deployment.environment", conf.DeploymentEnvironment},
    {"os.type", conf.OsType},
    {"os.description", conf.OsDescription},
    {"cloud.zone", conf.CloudZone},
    {"host.id", conf.HostID},
    {"host.name", conf.HostName},
    {"host.type", conf.HostType},
}));
builder.SetResource(resource);
...

However, to fetch host and cloud information we have to block the initialization process to make calls to AWS API. We would prefer not to block initialization because of this.

Is there a way to add tags to the resource after initialization? Do you guys think of an alternative solution?

[eddynaka]

For the caching strategy, yes, that would help with the allocation since we would only need to allocate the new Resource once.

For the enrichment part, it will affect performance when you use Enrich.

I thought I did commit the benchmark for that. I will create a new PR adding it. But you can look here: https://github.com/open-telemetry/opentelemetry-dotnet/pull/1261#issuecomment-695062784

For the processor question, yes that should work as well.

[cijothomas]

As per the current spec for Resource, resource is associated with a TracerProvider/MeterProvider, and is same for all the traces/metrics from that provider, and cannot be changed after provider creation. It is a bug that we allow overriding resource on a per span/activity level. This will very likely be fixed with one of the pending PRs. So do not count on this behaviour.