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HTTP/JSON Encoded for OTLP (open-telemetry/oteps#122)
* Add HTTP+JSON support for OTLP * update protocol detail desc * Rename title, handle line-breaking Co-authored-by: Bogdan Drutu <bogdandrutu@gmail.com>
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| # OTLP: JSON Encoding for OTLP/HTTP | ||
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| This is a proposal to add HTTP Transport extension supporting json serialization for | ||
| [OTLP](0035-opentelemetry-protocol.md) (OpenTelemetry Protocol). | ||
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| ## Table of Contents | ||
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| * [Motivation](#motivation) | ||
| * [OTLP/HTTP+JSON Protocol Details](#otlphttpjson-protocol-details) | ||
| * [JSON Mapping](#json-mapping) | ||
| * [Request](#request) | ||
| * [Response](#response) | ||
| * [Success](#success) | ||
| * [Failures](#failures) | ||
| * [Throttling](#throttling) | ||
| * [All Other Responses](#all-other-responses) | ||
| * [Connection](#connection) | ||
| * [Parallel Connections](#parallel-connections) | ||
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| ## Motivation | ||
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| Protobuf is a relatively big dependency, which some clients are not willing to take. For example, webjs, iOS/Android (in some scenarios, the size of the installation package is limited, do not want to introduce protobuf dependencies). Plain JSON is a smaller dependency and is built in the standard libraries of many programming languages. | ||
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| ## OTLP/HTTP+JSON Protocol Details | ||
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| OTLP/HTTP+JSON will be consistent with the [OTLP/HTTP](0099-otlp-http.md) specification except that the payload will use JSON instead of protobuf. | ||
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| ### JSON Mapping | ||
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| Use proto3 standard defined [JSON Mapping](https://developers.google.com/protocol-buffers/docs/proto3#json) for mapping between protobuf and json. `trace_id` and `span_id` is base64 encoded in OTLP/HTTP+JSON, not hex. | ||
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| ### Request | ||
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| Telemetry data is sent via HTTP POST request. | ||
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| The default URL path for requests that carry trace data is `/v1/traces` (for | ||
| example the full URL when connecting to "example.com" server will be | ||
| `https://example.com/v1/traces`). The request body is a JSON-encoded | ||
| [`ExportTraceServiceRequest`](https://github.com/open-telemetry/opentelemetry-proto/blob/e6c3c4a74d57f870a0d781bada02cb2b2c497d14/opentelemetry/proto/collector/trace/v1/trace_service.proto#L38) | ||
| message. | ||
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| The default URL path for requests that carry metric data is `/v1/metrics` and the | ||
| request body is a JSON-encoded | ||
| [`ExportMetricsServiceRequest`](https://github.com/open-telemetry/opentelemetry-proto/blob/e6c3c4a74d57f870a0d781bada02cb2b2c497d14/opentelemetry/proto/collector/metrics/v1/metrics_service.proto#L35) | ||
| message. | ||
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| The client MUST set "Content-Type: application/json" request header. The | ||
| client MAY gzip the content and in that case SHOULD include "Content-Encoding: | ||
| gzip" request header. The client MAY include "Accept-Encoding: gzip" request | ||
| header if it can receive gzip-encoded responses. | ||
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| Non-default URL paths for requests MAY be configured on the client and server | ||
| sides. | ||
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| ### Response | ||
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| #### Success | ||
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| On success the server MUST respond with `HTTP 200 OK`. Response body MUST be | ||
| JSON-encoded | ||
| [`ExportTraceServiceResponse`](https://github.com/open-telemetry/opentelemetry-proto/blob/e6c3c4a74d57f870a0d781bada02cb2b2c497d14/opentelemetry/proto/collector/trace/v1/trace_service.proto#L47) | ||
| message for traces and | ||
| [`ExportMetricsServiceResponse`](https://github.com/open-telemetry/opentelemetry-proto/blob/e6c3c4a74d57f870a0d781bada02cb2b2c497d14/opentelemetry/proto/collector/metrics/v1/metrics_service.proto#L44) | ||
| message for metrics. | ||
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| The server MUST set "Content-Type: application/json" response header. If | ||
| the request header "Accept-Encoding: gzip" is present in the request the server | ||
| MAY gzip-encode the response and set "Content-Encoding: gzip" response header. | ||
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| The server SHOULD respond with success no sooner than after successfully | ||
| decoding and validating the request. | ||
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| #### Failures | ||
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| If the processing of the request fails the server MUST respond with appropriate | ||
| `HTTP 4xx` or `HTTP 5xx` status code. See sections below for more details about | ||
| specific failure cases and HTTP status codes that should be used. | ||
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| Response body for all `HTTP 4xx` and `HTTP 5xx` responses MUST be a | ||
| JSON-encoded | ||
| [Status](https://godoc.org/google.golang.org/genproto/googleapis/rpc/status#Status) | ||
| message that describes the problem. | ||
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| This specification does not use `Status.code` field and the server MAY omit | ||
| `Status.code` field. The clients are not expected to alter their behavior based | ||
| on `Status.code` field but MAY record it for troubleshooting purposes. | ||
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| The `Status.message` field SHOULD contain a developer-facing error message as | ||
| defined in `Status` message schema. | ||
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| The server MAY include `Status.details` field with additional details. Read | ||
| below about what this field can contain in each specific failure case. | ||
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| #### Bad Data | ||
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| If the processing of the request fails because the request contains data that | ||
| cannot be decoded or is otherwise invalid and such failure is permanent then the | ||
| server MUST respond with `HTTP 400 Bad Request`. The `Status.details` field in | ||
| the response SHOULD contain a | ||
| [BadRequest](https://github.com/googleapis/googleapis/blob/d14bf59a446c14ef16e9931ebfc8e63ab549bf07/google/rpc/error_details.proto#L166) | ||
| that describes the bad data. | ||
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| The client MUST NOT retry the request when it receives `HTTP 400 Bad Request` | ||
| response. | ||
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| #### Throttling | ||
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| If the server receives more requests than the client is allowed or the server is | ||
| overloaded the server SHOULD respond with `HTTP 429 Too Many Requests` or | ||
| `HTTP 503 Service Unavailable` and MAY include | ||
| ["Retry-After"](https://tools.ietf.org/html/rfc7231#section-7.1.3) header with a | ||
| recommended time interval in seconds to wait before retrying. | ||
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| The client SHOULD honour the waiting interval specified in "Retry-After" header | ||
| if it is present. If the client receives `HTTP 429` or `HTTP 503` response and | ||
| "Retry-After" header is not present in the response then the client SHOULD | ||
| implement an exponential backoff strategy between retries. | ||
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| #### All Other Responses | ||
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| All other HTTP responses that are not explicitly listed in this document should | ||
| be treated according to HTTP specification. | ||
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| If the server disconnects without returning a response the client SHOULD retry | ||
| and send the same request. The client SHOULD implement an exponential backoff | ||
| strategy between retries to avoid overwhelming the server. | ||
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| ### Connection | ||
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| If the client is unable to connect to the server the client SHOULD retry the | ||
| connection using exponential backoff strategy between retries. The interval | ||
| between retries must have a random jitter. | ||
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| The client SHOULD keep the connection alive between requests. | ||
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| Server implementations MAY handle OTLP/gRPC, OTLP/HTTP requests and OTLP/HTTP+JSON on the same | ||
| port and multiplex the connections to the corresponding transport handler based | ||
| on "Content-Type" request header. | ||
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| ### Parallel Connections | ||
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| To achieve higher total throughput the client MAY send requests using several | ||
| parallel HTTP connections. In that case the maximum number of parallel | ||
| connections SHOULD be configurable. |