[exporter/influxdb] influxdb exporter does not accept v1_compatibility config

[otbe]

Component(s)

exporter/influxdb

What happened?

Description

I would like to use the influxdb exporter to send metrics to influx that the opentelemetry collector receives via OTLP.
Sadly I have to use the influx v1 compat mode and it seems like Im not able to configure it. Looks like theres a runtime error during constructing the basic auth header.

Steps to Reproduce

You can simple take the config from below and put it into a docker container.
Something like this works in my machine: docker run -v $(PWD)/otel.yml:/etc/otelcol-contrib/config.yaml otel/opentelemetry-collector-contrib:0.85.0

Expected Result

Should work :)

Actual Result

panic, runtime error. Collector stops working at all.

Collector version

0.85.0

Environment information

Environment

Docker image: otel/opentelemetry-collector-contrib:0.85.0

OpenTelemetry Collector configuration

extensions:
  health_check:

receivers:
  otlp:
    protocols:
      grpc:
        endpoint: 0.0.0.0:4317

processors:
  memory_limiter:
    check_interval: 1s
    limit_mib: 100
    spike_limit_mib: 20

exporters:
  influxdb:
    endpoint: https://foo.bar
    log_record_dimensions:
    span_dimensions:
    v1_compatibility:
      enabled: true
      db: foo
      username: bar
      password: baz

service:
  pipelines:
    metrics:
      receivers: [ otlp ]
      processors: [ memory_limiter ]
      exporters: [ influxdb ]

  extensions: [ health_check ]

Log output

panic: runtime error: index out of range [0] with length 0

goroutine 1 [running]:
encoding/base64.(*Encoding).Encode(0x68471e0?, {0x0?, 0x6fe1906?, 0x7da5688?}, {0x4001dfa478?, 0x40027b0a20?, 0x4001dfa448?})
        encoding/base64/base64.go:158 +0x284
github.com/open-telemetry/opentelemetry-collector-contrib/exporter/influxdbexporter.composeWriteURL(0x4002822900)
        github.com/open-telemetry/opentelemetry-collector-contrib/exporter/influxdbexporter@v0.85.0/writer.go:92 +0x25c
github.com/open-telemetry/opentelemetry-collector-contrib/exporter/influxdbexporter.newInfluxHTTPWriter({0x7dc84e0?, 0x4002841aa0}, 0x4002822900, {0x40023a4620, {0x7dcb000, 0x400282ec00}, {0x7dfd2a0, 0x40028411e0}, 0x0, {0x4002846740}})
        github.com/open-telemetry/opentelemetry-collector-contrib/exporter/influxdbexporter@v0.85.0/writer.go:43 +0x4c
github.com/open-telemetry/opentelemetry-collector-contrib/exporter/influxdbexporter.createMetricsExporter({0x7e45808, 0xc9f4dc0}, {{{0x40027b1288, 0x8}, {0x0, 0x0}}, {0x40023a4620, {0x7dcb000, 0x400282ec00}, {0x7dfd2a0, ...}, ...}, ...}, ...)
        github.com/open-telemetry/opentelemetry-collector-contrib/exporter/influxdbexporter@v0.85.0/factory.go:94 +0x194
go.opentelemetry.io/collector/exporter.CreateMetricsFunc.CreateMetricsExporter(...)

### Additional context

_No response_

[github-actions]

Pinging code owners:

• exporter/influxdb: @jacobmarble

See Adding Labels via Comments if you do not have permissions to add labels yourself.

[crobert-1]

This looks like a pretty simple out of bounds indexing error.

Here's the line hitting the exception:

func (enc *Encoding) Encode(dst, src []byte) {
    ...
		dst[di+0] = enc.encode[val>>18&0x3F]

Here's the code calling the above method:

func composeWriteURL(config *Config) (string, error) {
    ...
                if config.V1Compatibility.Username != "" && config.V1Compatibility.Password != "" {
			var basicAuth []byte
			base64.StdEncoding.Encode(basicAuth, []byte(config.V1Compatibility.Username+":"+string(config.V1Compatibility.Password)))
			config.HTTPClientSettings.Headers["Authorization"] = configopaque.String("Basic " + string(basicAuth))
		}

The Encode method is attempting to set the value at index 0 in the byte array, but the byte array is initialized without any space. In golang, this equates to nil with length 0.

The solution should be pretty simple, allocate the required space when declaring the slice.
Replace:

			var basicAuth []byte
			base64.StdEncoding.Encode(basicAuth, []byte(config.V1Compatibility.Username+":"+string(config.V1Compatibility.Password)))

With: (I renamed basicAuth to encodedAuth for clarity)

                       	authInfo := []byte(config.V1Compatibility.Username + ":" + string(config.V1Compatibility.Password))
                         // Allocate the right length of slice for the encoded byte array
			encodedAuth := make([]byte, base64.StdEncoding.EncodedLen(len(authInfo)))
			base64.StdEncoding.Encode(encodedAuth, authInfo)

[vv0s4k]

Ran into the same issue with opentelemetry-collector-contrib:0.88.0
May we expect it to get fixed in observable future?

[crobert-1]

Any contributions are appreciated! I don't think I'd be able to get around to testing the fix anytime soon.

[vv0s4k]

Any contributions are appreciated! I don't think I'd be able to get around to testing the fix anytime soon.

I see. I wish I knew Golang. I'd be able to help then.