Update OTLP exporter configuration to conform to the specification

[MrAlias]

The following configuration options and the interpreted environment variables need to be implemented to support the specification

Configuration Option	Description	Default	Env variable
Endpoint	Target to which the exporter is going to send spans or metrics. This MAY be configured to include a path (e.g. example.com/v1/traces).	localhost:55680	OTEL_EXPORTER_OTLP_ENDPOINT OTEL_EXPORTER_OTLP_SPAN_ENDPOINT OTEL_EXPORTER_OTLP_METRIC_ENDPOINT
Protocol	The protocol used to transmit the data. One of grpc,http/json,http/proto.	grpc	OTEL_EXPORTER_OTLP_PROTOCOL OTEL_EXPORTER_OTLP_SPAN_PROTOCOL OTEL_EXPORTER_OTLP_METRIC_PROTOCOL
Insecure	Whether to enable client transport security for the exporter's grpc or http connection.	false	OTEL_EXPORTER_OTLP_INSECURE OTEL_EXPORTER_OTLP_SPAN_INSECURE OTEL_EXPORTER_OTLP_METRIC_INSECURE
Certificate File	Certificate file for TLS credentials of gRPC client. Should only be used if insecure is set to false.	n/a	OTEL_EXPORTER_OTLP_CERTIFICATE OTEL_EXPORTER_OTLP_SPAN_CERTIFICATE OTEL_EXPORTER_OTLP_METRIC_CERTIFICATE
Headers	The headers associated with gRPC or HTTP requests.	n/a	OTEL_EXPORTER_OTLP_HEADERS OTEL_EXPORTER_OTLP_SPAN_HEADERS OTEL_EXPORTER_OTLP_METRIC_HEADERS
Compression	Compression key for supported compression types. Supported compression: gzip	no compression	OTEL_EXPORTER_OTLP_COMPRESSION OTEL_EXPORTER_OTLP_SPAN_COMPRESSION OTEL_EXPORTER_OTLP_METRIC_COMPRESSION
Timeout	Max waiting time for the backend to process each spans or metrics batch.	10s	OTEL_EXPORTER_OTLP_TIMEOUT OTEL_EXPORTER_OTLP_SPAN_TIMEOUT OTEL_EXPORTER_OTLP_METRIC_TIMEOUT

Tasks

• Update OTLP configuration to include all the options with defaults.
• Update the OTLP exporter to use the appropriate environment variables to configure the exproter.
• Update the compliance matrix when complete.

[MrAlias]

This is blocked by #1121 and #1122

[krnowak]

I'll try to push it forward.

[Miriam-R]

This is waiting on a review & merge from @MrAlias

[krnowak]

The code for this issue and #1121 and #1122 is here: https://github.com/krnowak/opentelemetry-go/tree/otlp-conn

[hermanbanken]

This seems to be unblocked. I would be great if the Golang version adheres to the spec 😄

I was investigating how the 2021 way of doing metrics should be, found OpenTelemetry, and following the DataDog guide they mention using OTEL_EXPORTER_OTLP_ENDPOINT while this is not actually supported by all implementations yet, I now learn.

The saddest part is that every individual developer needs to discover this from the source (I searched for OTEL_EXPORTER_OTLP_ENDPOINT). Or is spec-adherance-progress tracked somewhere central that I'm just overlooking?

[MrAlias]

@hermanbanken we are happy to accept contributions if you are looking to work on this issue. Please let me know if I can assign it to you. Also, please take a look at the linked project. It contains all the things the contributors of this project are working hard to resolve and release a compliant implementation of the 1.0.1 specification.

[paivagustavo]

I came across some questions when implementing this. The specs defines that one could configure the exporter protocol, i.e., one could change between gRPC, http/proto and http/json via a config or env variable. But, currently, we have separated exporters implementation for gRPC and HTTP (otlpgrpc.Driver and otlphttp.Driver) and the user need to instante one or the other, making it impossible to dynamically change the protocol.

Since both exporters do implements the OTLP exporter interface, we could unify the configurations and choose which implementation should be used based on With configs or via env variables. The downside about this approach, is that we do define some configs that are only used by one of those exporters, e.g., the trace path and the metrics path only applies to the HTTP exporter and the reconnection period applies only to the gRPC exporter.

Would it be a problem to have configurations that only works when a specific implementation used? We could see this the same as some configs that overrides others, e.g, the Insecure options makes the tls config to be ignored, the same way that a gRPC option would make the tracePath to be ignored.

[MrAlias]

@paivagustavo it looks like that environment variable and configuration option moved to a "reserved" status, making the current requirements (1.1.0 of the spec):

Configuration Option	Description	Default	Env variable
Endpoint	Target to which the exporter is going to send spans or metrics. The endpoint MUST be a valid URL with scheme (http or https) and host, and MAY contain a port and path. A scheme of https indicates a secure connection. When using OTEL_EXPORTER_OTLP_ENDPOINT with OTLP/HTTP, exporters SHOULD follow the collector convention of appending the version and signal to the path (e.g. v1/traces or v1/metrics). The per-signal endpoint configuration options take precedence and can be used to override this behavior. See the [OTLP Specification][otlphttp-req] for more details.	https://localhost:4317	OTEL_EXPORTER_OTLP_ENDPOINT OTEL_EXPORTER_OTLP_TRACES_ENDPOINT OTEL_EXPORTER_OTLP_METRICS_ENDPOINT
Certificate File	Path to certificate file for TLS credentials of gRPC client. Should only be used for a secure connection.	n/a	OTEL_EXPORTER_OTLP_CERTIFICATE OTEL_EXPORTER_OTLP_TRACES_CERTIFICATE OTEL_EXPORTER_OTLP_METRICS_CERTIFICATE
Headers	Key-value pairs to be used as headers associated with gRPC or HTTP requests. See Specifying headers for more details.	n/a	OTEL_EXPORTER_OTLP_HEADERS OTEL_EXPORTER_OTLP_TRACES_HEADERS OTEL_EXPORTER_OTLP_METRICS_HEADERS
Compression	Compression key for supported compression types. Supported compression: gzip	No value	OTEL_EXPORTER_OTLP_COMPRESSION OTEL_EXPORTER_OTLP_TRACES_COMPRESSION OTEL_EXPORTER_OTLP_METRICS_COMPRESSION
Timeout	Max waiting time for the backend to process each spans or metrics batch.	10s	OTEL_EXPORTER_OTLP_TIMEOUT OTEL_EXPORTER_OTLP_TRACES_TIMEOUT OTEL_EXPORTER_OTLP_METRICS_TIMEOUT

I think this means we can punt on answer this question for now.

[MrAlias]

At least, that is my reading of this section.

[calbot]

I'm confused...
I would like to be able to configure tracing through the documented environment variables only.
Is that possible?

[pellared]

@calbot Check the package documentation of the OTLP exporters.

[calbot]

@calbot Check the package documentation of the OTLP exporters.

Thanks for your response...
It looks like the package go.opentelemetry.io/contrib/exporters/autoexport with autoexport.NewSpanExporter(ctx) gets me closer to what I was looking for. I guess I was looking something along the lines of an "InitTelemetry" function that would read the environment variables and end up calling otel.SetTracerProvider & otel.SetMeterProvider with the right configuration.