Add HTTP protocol support to OTLP

[MrAlias]

Currently the OTLP exporter only export using the grpc protocol. Both the HTTP protocols required by the specification, http/json and http/protobuf, need to be supported.

Additionally, having gRPC libraries included in dependencies by default for all use of the OTLP exporter can be problematic for many users. Especially if these uses plan to use one of these HTTP protocols. When splitting out the supported protocols design thought needs to given to how we can possibly support a separated model. Possibly having a sub-module of the OTLP exporter module that contains "drivers", similar to the database/sql/driver, can achieve this.

[huikang]

Hi, @MrAlias , I am interested in this task. Please assign it to me, if no one has taken it. Thanks.

[huikang]

@MrAlias , I setup an oltp collector which receives HTTP/JSON POST request at port 55681. I was sending the following request with some test span content, which returns http code 200.

curl --location --request POST 'http://localhost:55681/v1/trace' \
--header 'Content-Type: application/json' \
--data-raw '{
    "trace_id":"ZGJhZmU2Yzc4Y2FkNjkwN2RhNTdjZWVlYThhYTFjNjQK",
    "span_id": "YzBmMTM1ZjU3MmNjNGI3ZAo=",
    "name": "test"
}'

However, the collector's zpage does not show any received data, so I think there is some wrong with the request body. Could you please provide some advice on how to form a valid http/JSON content of a span. Thanks.

[huikang]

I think I found some example at the receiver's test file and will give it a shot: https://github.com/open-telemetry/opentelemetry-collector/blob/e7e66939263ccbd99c9ac9352960c263d464263c/receiver/otlpreceiver/otlp_test.go#L101

[samm02]

hi @huikang i am also interested in seeing this feature implemented - could you let us know of progress, or would it be possible for me to assist in getting this across the line?

EDIT: also, is this issue the same as #860? they seem very similar

[huikang]

@samm02 , feel free to take it. Thanks.

EDIT: also, is this issue the same as #860? they seem very similar

yes, should be the same thing.

[MrAlias]

From this ticket this duplicated:

Implementation on the collector side for reference: open-telemetry/opentelemetry-collector#1021 (issue open-telemetry/opentelemetry-collector#881)

Originally posted by @nilebox in #860 (comment)

[MrAlias]

We may not need this for our RC. @punya will confirm if it is needed.

[punya]

According to https://github.com/open-telemetry/opentelemetry-specification/blob/v1.0.1/spec-compliance-matrix.md,

* For each type of exporter, OTLP, Zipkin, and Jaeger, implementing at least one of the supported formats is required. Implementing more than one formats is optional.

We already support OTLP/gRPC, so we are compliant. We can defer OTLP/HTTP to post-1.0.

@MrAlias @Aneurysm9 I will remove this issue from the project and I recommend that we remove the release:required-for-ga label as well.