feat(otel): support mapping otel environment variables to ddtrace env…

…ironment variables [backport 2.9] (#9360)

Backport f471e6b from #9298 to 2.9.

## Description
This provides mapping support between values set for OTEL environment
variables to Datadog equivalent tracing environment variables.

## Checklist

- [x] Change(s) are motivated and described in the PR description
- [x] Testing strategy is described if automated tests are not included
in the PR
- [x] Risks are described (performance impact, potential for breakage,
maintainability)
- [x] Change is maintainable (easy to change, telemetry, documentation)
- [x] [Library release note
guidelines](https://ddtrace.readthedocs.io/en/stable/releasenotes.html)
are followed or label `changelog/no-changelog` is set
- [x] Documentation is included (in-code, generated user docs, [public
corp docs](https://github.com/DataDog/documentation/))
- [x] Backport labels are set (if
[applicable](https://ddtrace.readthedocs.io/en/latest/contributing.html#backporting))
- [x] If this PR changes the public interface, I've notified
`@DataDog/apm-tees`.

## Reviewer Checklist

- [x] Title is accurate
- [x] All changes are related to the pull request's stated goal
- [x] Description motivates each change
- [x] Avoids breaking
[API](https://ddtrace.readthedocs.io/en/stable/versioning.html#interfaces)
changes
- [x] Testing strategy adequately addresses listed risks
- [x] Change is maintainable (easy to change, telemetry, documentation)
- [x] Release note makes sense to a user of the library
- [x] Author has acknowledged and discussed the performance implications
of this PR as reported in the benchmarks PR comment
- [x] Backport labels are set in a manner that is consistent with the
[release branch maintenance
policy](https://ddtrace.readthedocs.io/en/latest/contributing.html#backporting)

Co-authored-by: ddmclav <99694116+ddmclav@users.noreply.github.com>

ddtrace/settings/_otel_remapper.py

@@ -0,0 +1,191 @@
+import os
+import sys
+
+from ..constants import ENV_KEY
+from ..constants import VERSION_KEY
+from ..internal.logger import get_logger
+
+
+if sys.version_info >= (3, 8):
+    import typing
+else:
+    import typing_extensions as typing  # noqa: F401
+
+log = get_logger(__name__)
+
+
+OTEL_UNIFIED_TAG_MAPPINGS = {
+    "deployment.environment": ENV_KEY,
+    "service.name": "service",
+    "service.version": VERSION_KEY,
+}
+
+
+def _remap_otel_log_level(otel_value: str) -> str:
+    """Remaps the otel log level to ddtrace log level"""
+    if otel_value == "debug":
+        return "True"
+    else:
+        log.warning(
+            "ddtrace does not support otel log level '%s'. ddtrace only supports enabling debug logs.",
+            otel_value,
+        )
+        return "False"
+
+
+def _remap_otel_propagators(otel_value: str) -> str:
+    """Remaps the otel propagators to ddtrace propagators"""
+    accepted_styles = []
+    for style in otel_value.split(","):
+        style = style.strip().lower()
+        if style in ["b3", "b3multi", "datadog", "tracecontext", "none"]:
+            if style not in accepted_styles:
+                accepted_styles.append(style)
+        else:
+            log.warning("Following style not supported by ddtrace: %s.", style)
+    return ",".join(accepted_styles)
+
+
+def _remap_traces_sampler(otel_value: str) -> str:
+    """Remaps the otel trace sampler to ddtrace trace sampler"""
+    if otel_value in ["always_on", "always_off", "traceidratio"]:
+        log.warning(
+            "Trace sampler set from %s to parentbased_%s; only parent based sampling is supported.",
+            otel_value,
+            otel_value,
+        )
+        otel_value = f"parentbased_{otel_value}"
+    if otel_value == "parentbased_always_on":
+        return "1.0"
+    elif otel_value == "parentbased_always_off":
+        return "0.0"
+    elif otel_value == "parentbased_traceidratio":
+        return os.environ.get("OTEL_TRACES_SAMPLER_ARG", "1")
+    else:
+        log.warning("Unknown sampling configuration: %s.", otel_value)
+        return otel_value
+
+
+def _remap_traces_exporter(otel_value: str) -> str:
+    """Remaps the otel trace exporter to ddtrace trace enabled"""
+    if otel_value == "none":
+        return "False"
+    log.warning(
+        "A trace exporter value '%s' is set, but not supported. Traces will be exported to Datadog.", otel_value
+    )
+    return ""
+
+
+def _remap_metrics_exporter(otel_value: str) -> str:
+    """Remaps the otel metrics exporter to ddtrace metrics exporter"""
+    if otel_value == "none":
+        return "False"
+    log.warning(
+        "Metrics exporter value is set to unrecognized value: %s.",
+        otel_value,
+    )
+    return ""
+
+
+def _validate_logs_exporter(otel_value: str) -> typing.Literal[""]:
+    """Logs warning when OTEL Logs exporter is configured. DDTRACE does not support this configuration."""
+    if otel_value != "none":
+        log.warning(
+            "Unsupported OTEL logs exporter value detected: %s. Only the 'none' value is supported.", otel_value
+        )
+    return ""
+
+
+def _remap_otel_tags(otel_value: str) -> str:
+    """Remaps the otel tags to ddtrace tags"""
+    dd_tags: typing.List[str] = []
+
+    try:
+        otel_user_tag_dict: typing.Dict[str, str] = dict()
+        for tag in otel_value.split(","):
+            key, value = tag.split("=")
+            otel_user_tag_dict[key] = value
+
+        for key, value in otel_user_tag_dict.items():
+            if key.lower() in OTEL_UNIFIED_TAG_MAPPINGS:
+                dd_key = OTEL_UNIFIED_TAG_MAPPINGS[key.lower()]
+                dd_tags.insert(0, f"{dd_key}:{value}")
+            else:
+                dd_tags.append(f"{key}:{value}")
+    except Exception:
+        log.warning("DDTRACE failed to read OTEL_RESOURCE_ATTRIBUTES. This value is misformatted: %s", otel_value)
+
+    if len(dd_tags) > 10:
+        dd_tags, remaining_tags = dd_tags[:10], dd_tags[10:]
+        log.warning(
+            "To preserve metrics cardinality, only the following first 10 tags have been processed %s. "
+            "The following tags were not ingested: %s",
+            dd_tags,
+            remaining_tags,
+        )
+    return ",".join(dd_tags)
+
+
+def _remap_otel_sdk_config(otel_value: str) -> str:
+    """Remaps the otel sdk config to ddtrace sdk config"""
+    if otel_value == "false":
+        return "True"
+    elif otel_value == "true":
+        return "False"
+    else:
+        log.warning("OTEL_SDK_DISABLED='%s'  is not supported", otel_value)
+        return otel_value
+
+
+def _remap_default(otel_value: str) -> str:
+    """Remaps the otel default value to ddtrace default value"""
+    return otel_value
+
+
+ENV_VAR_MAPPINGS = {
+    "OTEL_SERVICE_NAME": ("DD_SERVICE", _remap_default),
+    "OTEL_LOG_LEVEL": ("DD_TRACE_DEBUG", _remap_otel_log_level),
+    "OTEL_PROPAGATORS": ("DD_TRACE_PROPAGATION_STYLE", _remap_otel_propagators),
+    "OTEL_TRACES_SAMPLER": ("DD_TRACE_SAMPLE_RATE", _remap_traces_sampler),
+    "OTEL_TRACES_EXPORTER": ("DD_TRACE_ENABLED", _remap_traces_exporter),
+    "OTEL_METRICS_EXPORTER": ("DD_RUNTIME_METRICS_ENABLED", _remap_metrics_exporter),
+    "OTEL_LOGS_EXPORTER": ("", _validate_logs_exporter),  # Does not set a DDTRACE environment variable.
+    "OTEL_RESOURCE_ATTRIBUTES": ("DD_TAGS", _remap_otel_tags),
+    "OTEL_SDK_DISABLED": ("DD_TRACE_OTEL_ENABLED", _remap_otel_sdk_config),
+}
+
+
+def otel_remapping():
+    """Checks for the existence of both OTEL and Datadog tracer environment variables and remaps them accordingly.
+    Datadog Environment variables take precedence over OTEL, but if there isn't a Datadog value present,
+    then OTEL values take their place.
+    """
+    user_envs = {key.upper(): value for key, value in os.environ.items()}
+
+    for otel_env, otel_value in user_envs.items():
+        if otel_env not in ENV_VAR_MAPPINGS:
+            continue
+
+        dd_env, otel_config_validator = ENV_VAR_MAPPINGS[otel_env]
+        if dd_env in user_envs:
+            log.debug(
+                "Datadog configuration %s is already set. OpenTelemetry configuration will be ignored: %s=%s",
+                dd_env,
+                otel_env,
+                otel_value,
+            )
+            continue
+
+        if otel_env not in ("OTEL_RESOURCE_ATTRIBUTES", "OTEL_SERVICE_NAME"):
+            # Resource attributes and service name are case-insensitive
+            otel_value = otel_value.lower()
+
+        mapped_value = otel_config_validator(otel_value)
+        if mapped_value:
+            os.environ[dd_env] = mapped_value
+            log.debug(
+                "OpenTelemetry configuration %s has been remapped to ddtrace configuration %s=%s",
+                otel_env,
+                dd_env,
+                mapped_value,
+            )

ddtrace/settings/config.py

@@ -34,6 +34,7 @@
 from ..internal.utils.formats import asbool
 from ..internal.utils.formats import parse_tags_str
 from ..pin import Pin
+from ._otel_remapper import otel_remapping as _otel_remapping
 from .http import HttpConfig
 from .integration import IntegrationConfig
 
@@ -380,10 +381,12 @@ def is_error_code(self, status_code):
             return False
 
     def __init__(self):
+        # Must map Otel configurations to Datadog configurations before creating the config object.
+        _otel_remapping()
         # Must come before _integration_configs due to __setattr__
         self._config = _default_config()
 
-        # use a dict as underlying storing mechanism for integration configs
+        # Use a dict as underlying storing mechanism for integration configs
         self._integration_configs = {}
 
         self._debug_mode = asbool(os.getenv("DD_TRACE_DEBUG", default=False))

releasenotes/notes/otel-env-var-support-for-dd-trace-py-d4378445a1405bab.yaml

@@ -0,0 +1,15 @@
+---
+features:
+  - |
+    tracing: Ensures the following OpenTelemetry environment variables are mapped to an equivalent Datadog configuration (datadog environment variables taking precedence in cases where both are configured)::
+      
+        OTEL_SERVICE_NAME -> DD_SERVICE
+        OTEL_LOG_LEVEL -> DD_TRACE_DEBUG
+        OTEL_PROPAGATORS -> DD_TRACE_PROPAGATION_STYLE
+        OTEL_TRACES_SAMPLER -> DD_TRACE_SAMPLE_RATE
+        OTEL_TRACES_EXPORTER -> DD_TRACE_ENABLED
+        OTEL_METRICS_EXPORTER -> DD_RUNTIME_METRICS_ENABLED
+        OTEL_LOGS_EXPORTER -> none
+        OTEL_RESOURCE_ATTRIBUTES -> DD_TAGS
+        OTEL_SDK_DISABLED -> DD_TRACE_OTEL_ENABLED
+