Add support for gzip compression to otel via tonic

[darach]

Describe the problem you are trying to solve

Add support for configurable compression to OpenTelemetry connectors in tremor.

Describe the solution you'd like

Minimally supports configurable gzip compression and decompression of otel payloads
in conformance with the gRPC over HTTP/2 requirements.

Notes

hyperium/tonic#282

hyperium/tonic#692

Requested by @ekarlso

[dak-x]

I believe we would want to provide a new optional field (say "compression") in the configuration for the "otel" connectors.
Note that following the discussion in hyperium/tonic#692 compression is triggered for each and every payload, meaning no per request compression.

Updated Config:

Client

pub(crate) struct Config {
    /// The hostname or IP address for the remote OpenTelemetry collector endpoint
    #[serde(default = "Default::default")]
    pub(crate) url: Url<OtelDefaults>,
    #[serde(default = "default_true")]
    pub(crate) logs: bool,
    /// Enables the trace service
    #[serde(default = "default_true")]
    pub(crate) trace: bool,
    /// Enables the metrics service
    #[serde(default = "default_true")]
    pub(crate) metrics: bool,
    
    // Do we require `Option` for backwards compatibility?
   pub(crate) compression: Option<CompressionEnum> 

}

similarly,

Server

pub(crate) struct Config {
    /// The hostname or IP address for the remote OpenTelemetry collector endpoint
    #[serde(default = "Default::default")]
    pub(crate) url: Url<OtelDefaults>,
    #[serde(default = "default_true")]
    pub(crate) logs: bool,
    /// Enables the trace service
    #[serde(default = "default_true")]
    pub(crate) trace: bool,
    /// Enables the metrics service
    #[serde(default = "default_true")]
    pub(crate) metrics: bool,

   // Do we require `Option` for backwards compatibility?
   pub(crate) compression: Option<CompressionEnum> 
}

Compression Enum

pub Enum CompressionEnum {
    gzip,
   // ... add others as requested
}

[Licenser]

Heya, this looks good to me :). There is no need for the Option if you implement Default for CompressionEnum and then tag the filed with #[serde(default = "Default::default")] - that way, when missing it's set to the default and the dance around checking if it's set or not is avoided.

[dak-x]

Have you evaluated upgrading tonic from 0.6.2 to 0.7.2? If not I would evaluate this, as 0.6.2 seems to only support gzip explicitly with the
<Client>.send_gzip() and <Client.accept_gzip() methods on TonicClent.

While the latest iteration has a slightly different method signature i.e.
<Client.send_compressed(Compression::gzip/..) and Client.accept_compressed(Compression::gzip/) refer here