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fix: Limit length of response body read to 4mb #2080

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f0bec26
fix: Limit length of response body read to 4mb
kaylareopelle Apr 8, 2026
a208184
test: add real-socket test for response body limit
robbkidd Apr 15, 2026
7af99b4
fix: use block form of request for streaming body access
robbkidd Apr 15, 2026
e1a8c00
test: assert body truncation in real-socket test
robbkidd Apr 15, 2026
54022d8
test: verify Net::HTTP doesn't buffer beyond the cap
robbkidd Apr 15, 2026
558562c
fix: close socket on oversized response to prevent full buffering
robbkidd Apr 15, 2026
7be8257
refactor: return truncation flag instead of ivar
robbkidd Apr 15, 2026
eefa743
test: assert body truncated logged, not a decode error
robbkidd Apr 22, 2026
83a8d4e
fix: return early when response body was truncated
robbkidd Apr 22, 2026
3727f79
Merge pull request #15 from robbkidd/robb.repro-response-body-limit
kaylareopelle Apr 24, 2026
97d3196
Rubocop
kaylareopelle Apr 24, 2026
f53c749
fix: Address feedback
kaylareopelle Jul 10, 2026
f4d895d
Merge branch 'main' into read-body-limit
kaylareopelle Jul 10, 2026
c449868
fix: Correctly adapt to recent exporter changes
kaylareopelle Jul 10, 2026
0ce6e36
Rubocop
kaylareopelle Jul 10, 2026
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44 changes: 37 additions & 7 deletions exporter/otlp-http/lib/opentelemetry/exporter/otlp/http/trace_exporter.rb
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Original file line number Diff line number Diff line change
Expand Up @@ -25,7 +25,8 @@ class TraceExporter # rubocop:disable Metrics/ClassLength
# Default timeouts in seconds.
KEEP_ALIVE_TIMEOUT = 30
RETRY_COUNT = 5
private_constant(:KEEP_ALIVE_TIMEOUT, :RETRY_COUNT)
RESPONSE_BODY_LIMIT = 4_194_304 # 4 MB
private_constant(:KEEP_ALIVE_TIMEOUT, :RETRY_COUNT, :RESPONSE_BODY_LIMIT)

ERROR_MESSAGE_INVALID_HEADERS = 'headers must be a String with comma-separated URL Encoded UTF-8 k=v pairs or a Hash'
private_constant(:ERROR_MESSAGE_INVALID_HEADERS)
Expand Down Expand Up @@ -158,18 +159,19 @@ def send_bytes(bytes, timeout:) # rubocop:disable Metrics/MethodLength

case response
when Net::HTTPSuccess
response.body # Read and discard body
response.read_body(nil) # Discard without reading into memory
SUCCESS
when Net::HTTPServiceUnavailable, Net::HTTPTooManyRequests
response.body # Read and discard body
response.read_body(nil) # Discard without reading into memory
redo if backoff?(retry_after: response['Retry-After'], retry_count: retry_count += 1, reason: response.code)
FAILURE
when Net::HTTPRequestTimeOut, Net::HTTPGatewayTimeOut, Net::HTTPBadGateway
response.body # Read and discard body
response.read_body(nil) # Discard without reading into memory
redo if backoff?(retry_count: retry_count += 1, reason: response.code)
FAILURE
when Net::HTTPBadRequest, Net::HTTPClientError, Net::HTTPServerError
log_status(response.body)
body = read_response_body(response)
log_status(body)
@metrics_reporter.add_to_counter('otel.otlp_exporter.failure', labels: { 'reason' => response.code })
FAILURE
when Net::HTTPRedirection
Expand Down Expand Up @@ -216,14 +218,42 @@ def handle_redirect(location)
end

def log_status(body)
truncation_note = @body_truncated ? ' (body truncated due to size limit)' : ''
status = Google::Rpc::Status.decode(body)
details = status.details.map do |detail|
klass_or_nil = ::Google::Protobuf::DescriptorPool.generated_pool.lookup(detail.type_name).msgclass
detail.unpack(klass_or_nil) if klass_or_nil
end.compact
OpenTelemetry.handle_error(message: "OTLP exporter received rpc.Status{message=#{status.message}, details=#{details}}")
OpenTelemetry.handle_error(message: "OTLP exporter received rpc.Status{message=#{status.message}, details=#{details}}#{truncation_note}")
rescue StandardError => e
OpenTelemetry.handle_error(exception: e, message: 'unexpected error decoding rpc.Status in OTLP::Exporter#log_status')
OpenTelemetry.handle_error(exception: e, message: "unexpected error decoding rpc.Status in OTLP::Exporter#log_status#{truncation_note}")
ensure
@body_truncated = false
end

def read_response_body(response)
return '' if response.nil?

body = +''
truncated = false

response.read_body do |chunk|
if body.bytesize + chunk.bytesize <= RESPONSE_BODY_LIMIT

@arielvalentin arielvalentin Apr 11, 2026

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Before starting to read the response body, should we not first read the content-length or transfer-encoding and short circuit if the body exceeds the limit?

IIUC the Go collector will switch to using chunked responses that exceed the 2KiB default buffer size. In cases where the response is less than 2KiB or the backend supports larger buffer sizes we may get the content-length responses and exit early.

https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/Content-Length

https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/Transfer-Encoding

@kaylareopelle kaylareopelle Apr 14, 2026

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I like the idea of using the headers to make this more performant!

Just to make sure I'm on the same page, are you proposing:

  • Use the transfer-encoding / content-length headers to determine body size
  • Skip chunking when the body is less than the limit and just return the body
  • Truncate the response using chunking for bodies that exceed the limit

Or are you suggesting something else?

@arielvalentin arielvalentin Apr 14, 2026

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My understanding is that it is either or.

The response will either have a Content-Length or Transfer-Encoding Chunked

In the case the Content-Length is present and it exceeds the size then discard the response body and exit immediately.

If it's a chunked response use the code you've introduced here.

body << chunk
else
remaining = RESPONSE_BODY_LIMIT - body.bytesize
body << chunk.byteslice(0, remaining) if remaining > 0
truncated = true
break
end
end

body.force_encoding('UTF-8')
@body_truncated = truncated
body
rescue StandardError => e
OpenTelemetry.handle_error(exception: e, message: 'error reading response body')
''
end

def measure_request_duration
Expand Down
77 changes: 77 additions & 0 deletions exporter/otlp-http/test/opentelemetry/exporter/otlp/http/trace_exporter_test.rb
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Original file line number Diff line number Diff line change
Expand Up @@ -742,4 +742,81 @@
end
end
end

describe 'response body reading' do
let(:exporter) { OpenTelemetry::Exporter::OTLP::HTTP::TraceExporter.new }
let(:span_data) { OpenTelemetry::TestHelpers.create_span_data }

it 'discards body for successful responses without reading into memory' do
stub_request(:post, 'http://localhost:4318/v1/traces').to_return(status: 200, body: 'success body')

result = exporter.export([span_data])

_(result).must_equal(success)
end

it 'discards body for retryable responses without reading into memory' do
stub_request(:post, 'http://localhost:4318/v1/traces')
.to_return(status: 503, body: 'service unavailable', headers: { 'Retry-After' => '0' })
.then.to_return(status: 200)

result = exporter.export([span_data])

_(result).must_equal(success)
end

it 'reads and parses error response body smaller than limit' do
log_stream = StringIO.new
logger = OpenTelemetry.logger
OpenTelemetry.logger = ::Logger.new(log_stream)

details = [::Google::Protobuf::Any.pack(::Google::Protobuf::StringValue.new(value: 'error details'))]
status = ::Google::Rpc::Status.encode(::Google::Rpc::Status.new(code: 3, message: 'invalid argument', details: details))
stub_request(:post, 'http://localhost:4318/v1/traces').to_return(status: 400, body: status)

result = exporter.export([span_data])

_(result).must_equal(export_failure)
_(log_stream.string).must_match(/invalid argument/)
_(log_stream.string).wont_match(/truncated/)
ensure
OpenTelemetry.logger = logger
end

it 'truncates error response body larger than 4 MB limit' do
log_stream = StringIO.new
logger = OpenTelemetry.logger
OpenTelemetry.logger = ::Logger.new(log_stream)

# Create a body larger than 4 MB
large_message = 'x' * 5_000_000 # 5 MB
details = [::Google::Protobuf::Any.pack(::Google::Protobuf::StringValue.new(value: large_message))]
large_status = ::Google::Rpc::Status.new(code: 3, message: 'large error', details: details)
large_body = ::Google::Rpc::Status.encode(large_status)

stub_request(:post, 'http://localhost:4318/v1/traces').to_return(status: 400, body: large_body)

result = exporter.export([span_data])

_(result).must_equal(export_failure)
_(log_stream.string).must_match(/body truncated due to size limit/)
ensure
OpenTelemetry.logger = logger
end

it 'handles malformed error response body gracefully' do
log_stream = StringIO.new
logger = OpenTelemetry.logger
OpenTelemetry.logger = ::Logger.new(log_stream)

stub_request(:post, 'http://localhost:4318/v1/traces').to_return(status: 400, body: 'not valid protobuf')

result = exporter.export([span_data])

_(result).must_equal(export_failure)
_(log_stream.string).must_match(/unexpected error decoding rpc.Status/)
ensure
OpenTelemetry.logger = logger
end
end
end
44 changes: 37 additions & 7 deletions exporter/otlp-logs/lib/opentelemetry/exporter/otlp/logs/logs_exporter.rb
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Original file line number Diff line number Diff line change
Expand Up @@ -31,7 +31,8 @@ class LogsExporter # rubocop:disable Metrics/ClassLength
# Default timeouts in seconds.
KEEP_ALIVE_TIMEOUT = 30
RETRY_COUNT = 5
private_constant(:KEEP_ALIVE_TIMEOUT, :RETRY_COUNT)
RESPONSE_BODY_LIMIT = 4_194_304 # 4 MB
private_constant(:KEEP_ALIVE_TIMEOUT, :RETRY_COUNT, :RESPONSE_BODY_LIMIT)

ERROR_MESSAGE_INVALID_HEADERS = 'headers must be a String with comma-separated URL Encoded UTF-8 k=v pairs or a Hash'
private_constant(:ERROR_MESSAGE_INVALID_HEADERS)
Expand Down Expand Up @@ -167,23 +168,24 @@ def send_bytes(bytes, timeout:) # rubocop:disable Metrics/CyclomaticComplexity,

case response
when Net::HTTPSuccess
response.body # Read and discard body
response.read_body(nil) # Discard without reading into memory
SUCCESS
when Net::HTTPServiceUnavailable, Net::HTTPTooManyRequests
response.body # Read and discard body
response.read_body(nil) # Discard without reading into memory
handle_http_error(response)
redo if backoff?(retry_after: response['Retry-After'], retry_count: retry_count += 1)
FAILURE
when Net::HTTPRequestTimeOut, Net::HTTPGatewayTimeOut, Net::HTTPBadGateway
response.body # Read and discard body
response.read_body(nil) # Discard without reading into memory
handle_http_error(response)
redo if backoff?(retry_count: retry_count += 1)
FAILURE
when Net::HTTPNotFound
handle_http_error(response)
FAILURE
when Net::HTTPBadRequest, Net::HTTPClientError, Net::HTTPServerError
log_status(response.body)
body = read_response_body(response)
log_status(body)
FAILURE
when Net::HTTPRedirection
@http.finish
Expand Down Expand Up @@ -234,14 +236,42 @@ def handle_redirect(location)
end

def log_status(body)
truncation_note = @body_truncated ? ' (body truncated due to size limit)' : ''
status = Google::Rpc::Status.decode(body)
details = status.details.map do |detail|
klass_or_nil = ::Google::Protobuf::DescriptorPool.generated_pool.lookup(detail.type_name).msgclass
detail.unpack(klass_or_nil) if klass_or_nil
end.compact
OpenTelemetry.handle_error(message: "OTLP logs exporter received rpc.Status{message=#{status.message}, details=#{details}}")
OpenTelemetry.handle_error(message: "OTLP logs exporter received rpc.Status{message=#{status.message}, details=#{details}}#{truncation_note}")
rescue StandardError => e
OpenTelemetry.handle_error(exception: e, message: 'unexpected error decoding rpc.Status in OTLP::Exporter#log_status')
OpenTelemetry.handle_error(exception: e, message: "unexpected error decoding rpc.Status in OTLP::Exporter#log_status#{truncation_note}")
ensure
@body_truncated = false
end

def read_response_body(response)
return '' if response.nil?

body = +''
truncated = false

response.read_body do |chunk|
if body.bytesize + chunk.bytesize <= RESPONSE_BODY_LIMIT
body << chunk
else
remaining = RESPONSE_BODY_LIMIT - body.bytesize
body << chunk.byteslice(0, remaining) if remaining > 0
truncated = true
break
end
end

body.force_encoding('UTF-8')
@body_truncated = truncated
body
rescue StandardError => e
OpenTelemetry.handle_error(exception: e, message: 'error reading response body')
''
end

def backoff?(retry_count:, retry_after: nil) # rubocop:disable Metrics/CyclomaticComplexity, Metrics/PerceivedComplexity
Expand Down
77 changes: 77 additions & 0 deletions exporter/otlp-logs/test/opentelemetry/exporter/otlp/logs_exporter_test.rb
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Original file line number Diff line number Diff line change
Expand Up @@ -955,4 +955,81 @@
end
end
end

describe 'response body reading' do
let(:exporter) { OpenTelemetry::Exporter::OTLP::Logs::LogsExporter.new }
let(:log_record_data) { OpenTelemetry::TestHelpers.create_log_record_data }

it 'discards body for successful responses without reading into memory' do
stub_request(:post, 'http://localhost:4318/v1/logs').to_return(status: 200, body: 'success body')

result = exporter.export([log_record_data])

_(result).must_equal(SUCCESS)
end

it 'discards body for retryable responses without reading into memory' do
stub_request(:post, 'http://localhost:4318/v1/logs')
.to_return(status: 503, body: 'service unavailable', headers: { 'Retry-After' => '0' })
.then.to_return(status: 200)

result = exporter.export([log_record_data])

_(result).must_equal(SUCCESS)
end

it 'reads and parses error response body smaller than limit' do
log_stream = StringIO.new
logger = OpenTelemetry.logger
OpenTelemetry.logger = ::Logger.new(log_stream)

details = [::Google::Protobuf::Any.pack(::Google::Protobuf::StringValue.new(value: 'error details'))]
status = ::Google::Rpc::Status.encode(::Google::Rpc::Status.new(code: 3, message: 'invalid argument', details: details))
stub_request(:post, 'http://localhost:4318/v1/logs').to_return(status: 400, body: status)

result = exporter.export([log_record_data])

_(result).must_equal(FAILURE)
_(log_stream.string).must_match(/invalid argument/)
_(log_stream.string).wont_match(/truncated/)
ensure
OpenTelemetry.logger = logger
end

it 'truncates error response body larger than 4 MB limit' do
log_stream = StringIO.new
logger = OpenTelemetry.logger
OpenTelemetry.logger = ::Logger.new(log_stream)

# Create a body larger than 4 MB
large_message = 'x' * 5_000_000 # 5 MB
details = [::Google::Protobuf::Any.pack(::Google::Protobuf::StringValue.new(value: large_message))]
large_status = ::Google::Rpc::Status.new(code: 3, message: 'large error', details: details)
large_body = ::Google::Rpc::Status.encode(large_status)

stub_request(:post, 'http://localhost:4318/v1/logs').to_return(status: 400, body: large_body)

result = exporter.export([log_record_data])

_(result).must_equal(FAILURE)
_(log_stream.string).must_match(/body truncated due to size limit/)
ensure
OpenTelemetry.logger = logger
end

it 'handles malformed error response body gracefully' do
log_stream = StringIO.new
logger = OpenTelemetry.logger
OpenTelemetry.logger = ::Logger.new(log_stream)

stub_request(:post, 'http://localhost:4318/v1/logs').to_return(status: 400, body: 'not valid protobuf')

result = exporter.export([log_record_data])

_(result).must_equal(FAILURE)
_(log_stream.string).must_match(/unexpected error decoding rpc.Status/)
ensure
OpenTelemetry.logger = logger
end
end
end
9 changes: 5 additions & 4 deletions exporter/otlp-metrics/lib/opentelemetry/exporter/otlp/metrics/metrics_exporter.rb
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Original file line number Diff line number Diff line change
Expand Up @@ -120,23 +120,24 @@ def send_bytes(bytes, timeout:)
response = @http.request(request)
case response
when Net::HTTPSuccess
response.body # Read and discard body
response.read_body(nil) # Discard without reading into memory
SUCCESS
when Net::HTTPServiceUnavailable, Net::HTTPTooManyRequests
response.body # Read and discard body
response.read_body(nil) # Discard without reading into memory
redo if backoff?(retry_after: response['Retry-After'], retry_count: retry_count += 1, reason: response.code)
OpenTelemetry.logger.warn('Net::HTTPServiceUnavailable/Net::HTTPTooManyRequests in MetricsExporter#send_bytes')
FAILURE
when Net::HTTPRequestTimeOut, Net::HTTPGatewayTimeOut, Net::HTTPBadGateway
response.body # Read and discard body
response.read_body(nil) # Discard without reading into memory
redo if backoff?(retry_count: retry_count += 1, reason: response.code)
OpenTelemetry.logger.warn('Net::HTTPRequestTimeOut/Net::HTTPGatewayTimeOut/Net::HTTPBadGateway in MetricsExporter#send_bytes')
FAILURE
when Net::HTTPNotFound
OpenTelemetry.handle_error(message: "OTLP metrics_exporter received http.code=404 for uri: '#{@path}'")
FAILURE
when Net::HTTPBadRequest, Net::HTTPClientError, Net::HTTPServerError
log_status(response.body)
body = read_response_body(response)
log_status(body)
OpenTelemetry.logger.warn('Net::HTTPBadRequest/Net::HTTPClientError/Net::HTTPServerError in MetricsExporter#send_bytes')
FAILURE
when Net::HTTPRedirection
Expand Down
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