Prometheus - custom metrics support + other improvements (#7489)

* fix(prometheus.py): refactor litellm_input_tokens_metric to use label factory

makes adding new metrics easier

* feat(prometheus.py): add 'request_model' to 'litellm_input_tokens_metric'

* refactor(prometheus.py): refactor 'litellm_output_tokens_metric' to use label factory

makes adding new metrics easier

* feat(prometheus.py): emit requested model in 'litellm_output_tokens_metric'

* feat(prometheus.py): support tracking success events with custom metrics

* refactor(prometheus.py): refactor '_set_latency_metrics' to just use the initially created enum values dictionary

reduces scope for missing values

* feat(prometheus.py): refactor all tags to support custom metadata tags

enables metadata tags to be used across for e2e tracking

* fix(prometheus.py): fix requested model on success event enum_values

* test: fix test

* test: fix test

* test: handle filenotfound error

* docs(prometheus.md): add new values to prometheus

* docs(prometheus.md): document adding custom metrics on prometheus

* bump: version 1.56.5 → 1.56.6

docs/my-website/docs/proxy/prometheus.md

@@ -64,9 +64,9 @@ Use this for for tracking per [user, key, team, etc.](virtual_keys)
 | Metric Name          | Description                          |
 |----------------------|--------------------------------------|
 | `litellm_spend_metric`                | Total Spend, per `"user", "key", "model", "team", "end-user"`                 |
-| `litellm_total_tokens`         | input + output tokens per `"user", "key", "model", "team", "end-user"`     |
-| `litellm_input_tokens`         | input tokens per `"user", "key", "model", "team", "end-user"`              |
-| `litellm_output_tokens`        | output tokens per `"user", "key", "model", "team", "end-user"`             |
+| `litellm_total_tokens`         | input + output tokens per `"end_user", "hashed_api_key", "api_key_alias", "requested_model", "team", "team_alias", "user", "model"`     |
+| `litellm_input_tokens`         | input tokens per `"end_user", "hashed_api_key", "api_key_alias", "requested_model", "team", "team_alias", "user", "model"`     |
+| `litellm_output_tokens`        | output tokens per `"end_user", "hashed_api_key", "api_key_alias", "requested_model", "team", "team_alias", "user", "model"`             |
 
 ## Proxy Level Tracking Metrics
 
@@ -134,8 +134,8 @@ Use this for LLM API Error monitoring and tracking remaining rate limits and tok
 
 | Metric Name          | Description                          |
 |----------------------|--------------------------------------|
-| `litellm_request_total_latency_metric`             | Total latency (seconds) for a request to LiteLLM Proxy Server - tracked for labels `model`, `hashed_api_key`, `api_key_alias`, `team`, `team_alias` |
-| `litellm_llm_api_latency_metric`             | Latency (seconds) for just the LLM API call - tracked for labels `model`, `hashed_api_key`, `api_key_alias`, `team`, `team_alias` |
+| `litellm_request_total_latency_metric`             | Total latency (seconds) for a request to LiteLLM Proxy Server - tracked for labels "end_user", "hashed_api_key", "api_key_alias", "requested_model", "team", "team_alias", "user", "model" |
+| `litellm_llm_api_latency_metric`  | Latency (seconds) for just the LLM API call - tracked for labels "model", "hashed_api_key", "api_key_alias", "team", "team_alias", "requested_model", "end_user", "user" |
 | `litellm_llm_api_time_to_first_token_metric`             | Time to first token for LLM API call - tracked for labels `model`, `hashed_api_key`, `api_key_alias`, `team`, `team_alias` [Note: only emitted for streaming requests] |
 
 ## Virtual Key - Budget, Rate Limit Metrics
@@ -149,6 +149,55 @@ Metrics used to track LiteLLM Proxy Budgeting and Rate limiting logic
 | `litellm_remaining_api_key_requests_for_model`                | Remaining Requests for a LiteLLM virtual API key, only if a model-specific rate limit (rpm) has been set for that virtual key. Labels: `"hashed_api_key", "api_key_alias", "model"`|
 | `litellm_remaining_api_key_tokens_for_model`                | Remaining Tokens for a LiteLLM virtual API key, only if a model-specific token limit (tpm) has been set for that virtual key. Labels: `"hashed_api_key", "api_key_alias", "model"`|
 
+## [BETA] Custom Metrics
+
+Track custom metrics on prometheus on all events mentioned above. 
+
+1. Define the custom metrics in the `config.yaml`
+
+```yaml
+model_list:
+  - model_name: openai/gpt-3.5-turbo
+    litellm_params:
+      model: openai/gpt-3.5-turbo
+      api_key: os.environ/OPENAI_API_KEY
+
+litellm_settings:
+  callbacks: ["prometheus"]
+  custom_prometheus_metadata_labels: ["metadata.foo", "metadata.bar"]
+```
+
+2. Make a request with the custom metadata labels
+
+```bash
+curl -L -X POST 'http://0.0.0.0:4000/v1/chat/completions' \
+-H 'Content-Type: application/json' \
+-H 'Authorization: Bearer <LITELLM_API_KEY>' \
+-d '{
+    "model": "openai/gpt-3.5-turbo",
+    "messages": [
+      {
+        "role": "user",
+        "content": [
+          {
+            "type": "text",
+            "text": "What'\''s in this image?"
+          }
+        ]
+      }
+    ],
+    "max_tokens": 300,
+    "metadata": {
+        "foo": "hello world"
+    }
+}'
+```
+
+3. Check your `/metrics` endpoint for the custom metrics  
+
+```
+... "tag": "hello world" ...
+```
 
 
 ## Monitor System Health
@@ -170,6 +219,7 @@ litellm_settings:
 | `litellm_redis_fails`         | Number of failed redis calls    |
 | `litellm_self_latency`         | Histogram latency for successful litellm api call    |
 
+
 ## **🔥 LiteLLM Maintained Grafana Dashboards **
 
 Link to Grafana Dashboards maintained by LiteLLM
@@ -194,6 +244,7 @@ Here is a screenshot of the metrics you can monitor with the LiteLLM Grafana Das
 | `litellm_requests_metric`             | **deprecated** use `litellm_proxy_total_requests_metric` |
 
 
+
 ## FAQ 
 
 ### What are `_created` vs. `_total` metrics?

litellm/__init__.py

@@ -308,6 +308,7 @@ tag_budget_config: Optional[Dict[str, BudgetConfig]] = None
 max_end_user_budget: Optional[float] = None
 disable_end_user_cost_tracking: Optional[bool] = None
 disable_end_user_cost_tracking_prometheus_only: Optional[bool] = None
+custom_prometheus_metadata_labels: Optional[List[str]] = None
 #### REQUEST PRIORITIZATION ####
 priority_reservation: Optional[Dict[str, float]] = None
 #### RELIABILITY ####

litellm/integrations/prometheus.py

@@ -5,6 +5,7 @@ import sys
 from datetime import datetime, timedelta
 from typing import List, Optional, cast
 
+import litellm
 from litellm._logging import print_verbose, verbose_logger
 from litellm.integrations.custom_logger import CustomLogger
 from litellm.proxy._types import UserAPIKeyAuth
@@ -139,15 +140,7 @@ class PrometheusLogger(CustomLogger):
             self.litellm_input_tokens_metric = Counter(
                 "litellm_input_tokens",
                 "Total number of input tokens from LLM requests",
-                labelnames=[
-                    "end_user",
-                    "hashed_api_key",
-                    "api_key_alias",
-                    "model",
-                    "team",
-                    "team_alias",
-                    "user",
-                ],
+                labelnames=PrometheusMetricLabels.litellm_input_tokens_metric.value,
             )
 
             # Counter for input tokens by tag
@@ -162,15 +155,7 @@ class PrometheusLogger(CustomLogger):
             self.litellm_output_tokens_metric = Counter(
                 "litellm_output_tokens",
                 "Total number of output tokens from LLM requests",
-                labelnames=[
-                    "end_user",
-                    "hashed_api_key",
-                    "api_key_alias",
-                    "model",
-                    "team",
-                    "team_alias",
-                    "user",
-                ],
+                labelnames=PrometheusMetricLabels.litellm_output_tokens_metric.value,
             )
 
             # Counter for output tokens by tag
@@ -408,6 +393,17 @@ class PrometheusLogger(CustomLogger):
         output_tokens = standard_logging_payload["completion_tokens"]
         tokens_used = standard_logging_payload["total_tokens"]
         response_cost = standard_logging_payload["response_cost"]
+        _requester_metadata = standard_logging_payload["metadata"].get(
+            "requester_metadata"
+        )
+        if standard_logging_payload is not None and isinstance(
+            standard_logging_payload, dict
+        ):
+            _tags = get_tags_from_standard_logging_payload(
+                cast(StandardLoggingPayload, standard_logging_payload)
+            )
+        else:
+            _tags = []
 
         print_verbose(
             f"inside track_prometheus_metrics, model {model}, response_cost {response_cost}, tokens_used {tokens_used}, end_user_id {end_user_id}, user_api_key {user_api_key}"
@@ -417,11 +413,19 @@ class PrometheusLogger(CustomLogger):
             end_user=end_user_id,
             hashed_api_key=user_api_key,
             api_key_alias=user_api_key_alias,
-            requested_model=model,
+            requested_model=standard_logging_payload["model_group"],
             team=user_api_team,
             team_alias=user_api_team_alias,
             user=user_id,
             status_code="200",
+            model=model,
+            litellm_model_name=model,
+            tags=_tags,
+            model_id=standard_logging_payload["model_id"],
+            api_base=standard_logging_payload["api_base"],
+            api_provider=standard_logging_payload["custom_llm_provider"],
+            exception_status=None,
+            exception_class=None,
         )
 
         if (
@@ -459,6 +463,7 @@ class PrometheusLogger(CustomLogger):
             user_api_team=user_api_team,
             user_api_team_alias=user_api_team_alias,
             user_id=user_id,
+            enum_values=enum_values,
         )
 
         # remaining budget metrics
@@ -490,6 +495,7 @@ class PrometheusLogger(CustomLogger):
             # 1. We just checked if isinstance(standard_logging_payload, dict). Pyright complains.
             # 2. Pyright does not allow us to run isinstance(standard_logging_payload, StandardLoggingPayload) <- this would be ideal
             standard_logging_payload=standard_logging_payload,  # type: ignore
+            enum_values=enum_values,
         )
 
         # set x-ratelimit headers
@@ -524,6 +530,7 @@ class PrometheusLogger(CustomLogger):
         user_api_team: Optional[str],
         user_api_team_alias: Optional[str],
         user_id: Optional[str],
+        enum_values: UserAPIKeyLabelValues,
     ):
         # token metrics
         self.litellm_tokens_metric.labels(
@@ -536,7 +543,10 @@ class PrometheusLogger(CustomLogger):
             user_id,
         ).inc(standard_logging_payload["total_tokens"])
 
-        _tags = standard_logging_payload["request_tags"]
+        if standard_logging_payload is not None and isinstance(
+            standard_logging_payload, dict
+        ):
+            _tags = get_tags_from_standard_logging_payload(standard_logging_payload)
             for tag in _tags:
                 self.litellm_tokens_by_tag_metric.labels(
                     **{
@@ -544,15 +554,13 @@ class PrometheusLogger(CustomLogger):
                     }
                 ).inc(standard_logging_payload["total_tokens"])
 
-        self.litellm_input_tokens_metric.labels(
-            end_user_id,
-            user_api_key,
-            user_api_key_alias,
-            model,
-            user_api_team,
-            user_api_team_alias,
-            user_id,
-        ).inc(standard_logging_payload["prompt_tokens"])
+        _labels = prometheus_label_factory(
+            supported_enum_labels=PrometheusMetricLabels.litellm_input_tokens_metric.value,
+            enum_values=enum_values,
+        )
+        self.litellm_input_tokens_metric.labels(**_labels).inc(
+            standard_logging_payload["prompt_tokens"]
+        )
 
         for tag in _tags:
             self.litellm_input_tokens_by_tag_metric.labels(
@@ -561,15 +569,14 @@ class PrometheusLogger(CustomLogger):
                 }
             ).inc(standard_logging_payload["prompt_tokens"])
 
-        self.litellm_output_tokens_metric.labels(
-            end_user_id,
-            user_api_key,
-            user_api_key_alias,
-            model,
-            user_api_team,
-            user_api_team_alias,
-            user_id,
-        ).inc(standard_logging_payload["completion_tokens"])
+        _labels = prometheus_label_factory(
+            supported_enum_labels=PrometheusMetricLabels.litellm_output_tokens_metric.value,
+            enum_values=enum_values,
+        )
+
+        self.litellm_output_tokens_metric.labels(**_labels).inc(
+            standard_logging_payload["completion_tokens"]
+        )
 
         for tag in _tags:
             self.litellm_output_tokens_by_tag_metric.labels(
@@ -685,6 +692,7 @@ class PrometheusLogger(CustomLogger):
         user_api_team: Optional[str],
         user_api_team_alias: Optional[str],
         standard_logging_payload: StandardLoggingPayload,
+        enum_values: UserAPIKeyLabelValues,
     ):
         # latency metrics
         model_parameters: dict = standard_logging_payload["model_parameters"]
@@ -694,24 +702,6 @@ class PrometheusLogger(CustomLogger):
 
         completion_start_time = kwargs.get("completion_start_time", None)
 
-        enum_values = UserAPIKeyLabelValues(
-            end_user=standard_logging_payload["metadata"]["user_api_key_end_user_id"],
-            user=standard_logging_payload["metadata"]["user_api_key_user_id"],
-            hashed_api_key=user_api_key,
-            api_key_alias=user_api_key_alias,
-            team=user_api_team,
-            team_alias=user_api_team_alias,
-            requested_model=standard_logging_payload["model_group"],
-            model=model,
-            litellm_model_name=standard_logging_payload["model_group"],
-            tags=standard_logging_payload["request_tags"],
-            model_id=standard_logging_payload["model_id"],
-            api_base=standard_logging_payload["api_base"],
-            api_provider=standard_logging_payload["custom_llm_provider"],
-            exception_status=None,
-            exception_class=None,
-        )
-
         if (
             completion_start_time is not None
             and isinstance(completion_start_time, datetime)
@@ -841,6 +831,12 @@ class PrometheusLogger(CustomLogger):
         """
         try:
             _tags = cast(List[str], request_data.get("tags") or [])
+            request_metadata = request_data.get("metadata", {})
+            metadata_tags: Optional[List[str]] = None
+            if request_metadata is not None and isinstance(request_metadata, dict):
+                metadata_tags = get_tag_from_metadata(metadata=request_metadata)
+            if metadata_tags is not None:
+                _tags.extend(metadata_tags)
             enum_values = UserAPIKeyLabelValues(
                 end_user=user_api_key_dict.end_user_id,
                 user=user_api_key_dict.user_id,
@@ -980,7 +976,12 @@ class PrometheusLogger(CustomLogger):
             ).inc()
 
             # tag based tracking
-            _tags = standard_logging_payload["request_tags"]
+            if standard_logging_payload is not None and isinstance(
+                standard_logging_payload, dict
+            ):
+                _tags = get_tags_from_standard_logging_payload(
+                    cast(StandardLoggingPayload, standard_logging_payload)
+                )
                 for tag in _tags:
                     self.litellm_deployment_failure_by_tag_responses.labels(
                         **{
@@ -1201,6 +1202,7 @@ class PrometheusLogger(CustomLogger):
         )
         _new_model = kwargs.get("model")
         _tags = cast(List[str], kwargs.get("tags") or [])
+
         enum_values = UserAPIKeyLabelValues(
             requested_model=original_model_group,
             fallback_model=_new_model,
@@ -1392,3 +1394,45 @@ def prometheus_label_factory(
         )
 
     return filtered_labels
+
+
+def get_tags_from_standard_logging_payload(
+    standard_logging_payload: StandardLoggingPayload,
+) -> List[str]:
+    _tags = standard_logging_payload["request_tags"]
+    _requester_metadata = standard_logging_payload["metadata"].get("requester_metadata")
+    metadata_tags: Optional[List[str]] = None
+    if _requester_metadata is not None:
+        metadata_tags = get_tag_from_metadata(metadata=_requester_metadata)
+    if metadata_tags is not None:
+        _tags.extend(metadata_tags)
+
+    return _tags
+
+
+def get_tag_from_metadata(metadata: dict) -> Optional[List[str]]:
+    """
+    Get tag from metadata
+    """
+    keys = litellm.custom_prometheus_metadata_labels
+    if keys is None or len(keys) == 0:
+        return None
+
+    result: List[str] = []
+
+    for key in keys:
+        # Split the dot notation key into parts
+        key = key.replace("metadata.", "", 1) if key.startswith("metadata.") else key
+
+        keys_parts = key.split(".")
+        # Traverse through the dictionary using the parts
+        value = metadata
+        for part in keys_parts:
+            value = value.get(part, None)  # Get the value, return None if not found
+            if value is None:
+                break
+
+        if value is not None and isinstance(value, str):
+            result.append(value)
+
+    return result

litellm/types/integrations/prometheus.py

@@ -164,6 +164,28 @@ class PrometheusMetricLabels(Enum):
         UserAPIKeyLabelNames.TAG.value,
     ]
 
+    litellm_input_tokens_metric = [
+        UserAPIKeyLabelNames.END_USER.value,
+        UserAPIKeyLabelNames.API_KEY_HASH.value,
+        UserAPIKeyLabelNames.API_KEY_ALIAS.value,
+        UserAPIKeyLabelNames.v1_LITELLM_MODEL_NAME.value,
+        UserAPIKeyLabelNames.TEAM.value,
+        UserAPIKeyLabelNames.TEAM_ALIAS.value,
+        UserAPIKeyLabelNames.USER.value,
+        UserAPIKeyLabelNames.REQUESTED_MODEL.value,
+    ]
+
+    litellm_output_tokens_metric = [
+        UserAPIKeyLabelNames.END_USER.value,
+        UserAPIKeyLabelNames.API_KEY_HASH.value,
+        UserAPIKeyLabelNames.API_KEY_ALIAS.value,
+        UserAPIKeyLabelNames.v1_LITELLM_MODEL_NAME.value,
+        UserAPIKeyLabelNames.TEAM.value,
+        UserAPIKeyLabelNames.TEAM_ALIAS.value,
+        UserAPIKeyLabelNames.USER.value,
+        UserAPIKeyLabelNames.REQUESTED_MODEL.value,
+    ]
+
     litellm_deployment_successful_fallbacks = [
         UserAPIKeyLabelNames.REQUESTED_MODEL.value,
         UserAPIKeyLabelNames.FALLBACK_MODEL.value,

tests/logging_callback_tests/test_prometheus_unit_tests.py

@@ -14,7 +14,11 @@ from prometheus_client import REGISTRY, CollectorRegistry
 import litellm
 from litellm import completion
 from litellm._logging import verbose_logger
-from litellm.integrations.prometheus import PrometheusLogger, UserAPIKeyLabelValues
+from litellm.integrations.prometheus import (
+    PrometheusLogger,
+    UserAPIKeyLabelValues,
+    get_tag_from_metadata,
+)
 from litellm.llms.custom_httpx.http_handler import AsyncHTTPHandler
 from litellm.types.utils import (
     StandardLoggingPayload,
@@ -190,6 +194,16 @@ def test_increment_token_metrics(prometheus_logger):
     standard_logging_payload["prompt_tokens"] = 50
     standard_logging_payload["completion_tokens"] = 50
 
+    enum_values = UserAPIKeyLabelValues(
+        litellm_model_name=standard_logging_payload["model"],
+        api_provider=standard_logging_payload["custom_llm_provider"],
+        hashed_api_key=standard_logging_payload["metadata"]["user_api_key_hash"],
+        api_key_alias=standard_logging_payload["metadata"]["user_api_key_alias"],
+        team=standard_logging_payload["metadata"]["user_api_key_team_id"],
+        team_alias=standard_logging_payload["metadata"]["user_api_key_team_alias"],
+        **standard_logging_payload,
+    )
+
     prometheus_logger._increment_token_metrics(
         standard_logging_payload,
         end_user_id="user1",
@@ -199,6 +213,7 @@ def test_increment_token_metrics(prometheus_logger):
         user_api_team="team1",
         user_api_team_alias="team_alias1",
         user_id="user1",
+        enum_values=enum_values,
     )
 
     prometheus_logger.litellm_tokens_metric.labels.assert_called_once_with(
@@ -207,14 +222,28 @@ def test_increment_token_metrics(prometheus_logger):
     prometheus_logger.litellm_tokens_metric.labels().inc.assert_called_once_with(100)
 
     prometheus_logger.litellm_input_tokens_metric.labels.assert_called_once_with(
-        "user1", "key1", "alias1", "gpt-3.5-turbo", "team1", "team_alias1", "user1"
+        end_user=None,
+        user=None,
+        hashed_api_key="test_hash",
+        api_key_alias="test_alias",
+        team="test_team",
+        team_alias="test_team_alias",
+        requested_model=None,
+        model="gpt-3.5-turbo",
     )
     prometheus_logger.litellm_input_tokens_metric.labels().inc.assert_called_once_with(
         50
     )
 
     prometheus_logger.litellm_output_tokens_metric.labels.assert_called_once_with(
-        "user1", "key1", "alias1", "gpt-3.5-turbo", "team1", "team_alias1", "user1"
+        end_user=None,
+        user=None,
+        hashed_api_key="test_hash",
+        api_key_alias="test_alias",
+        team="test_team",
+        team_alias="test_team_alias",
+        requested_model=None,
+        model="gpt-3.5-turbo",
     )
     prometheus_logger.litellm_output_tokens_metric.labels().inc.assert_called_once_with(
         50
@@ -274,6 +303,18 @@ def test_set_latency_metrics(prometheus_logger):
     prometheus_logger.litellm_llm_api_latency_metric = MagicMock()
     prometheus_logger.litellm_request_total_latency_metric = MagicMock()
 
+    enum_values = UserAPIKeyLabelValues(
+        litellm_model_name=standard_logging_payload["model"],
+        api_provider=standard_logging_payload["custom_llm_provider"],
+        hashed_api_key=standard_logging_payload["metadata"]["user_api_key_hash"],
+        api_key_alias=standard_logging_payload["metadata"]["user_api_key_alias"],
+        team=standard_logging_payload["metadata"]["user_api_key_team_id"],
+        team_alias=standard_logging_payload["metadata"]["user_api_key_team_alias"],
+        requested_model=standard_logging_payload["model_group"],
+        user=standard_logging_payload["metadata"]["user_api_key_user_id"],
+        **standard_logging_payload,
+    )
+
     now = datetime.now()
     kwargs = {
         "end_time": now,  # when the request ends
@@ -291,6 +332,7 @@ def test_set_latency_metrics(prometheus_logger):
         user_api_team="team1",
         user_api_team_alias="team_alias1",
         standard_logging_payload=standard_logging_payload,
+        enum_values=enum_values,
     )
 
     # completion_start_time - api_call_start_time
@@ -303,14 +345,14 @@ def test_set_latency_metrics(prometheus_logger):
 
     # end_time - api_call_start_time
     prometheus_logger.litellm_llm_api_latency_metric.labels.assert_called_once_with(
-        model="gpt-3.5-turbo",
-        hashed_api_key="key1",
-        api_key_alias="alias1",
-        team="team1",
-        team_alias="team_alias1",
+        end_user=None,
         user="test_user",
-        end_user="test_end_user",
+        hashed_api_key="test_hash",
+        api_key_alias="test_alias",
+        team="test_team",
+        team_alias="test_team_alias",
         requested_model="openai-gpt",
+        model="gpt-3.5-turbo",
     )
     prometheus_logger.litellm_llm_api_latency_metric.labels().observe.assert_called_once_with(
         1.5
@@ -318,13 +360,13 @@ def test_set_latency_metrics(prometheus_logger):
 
     # total latency for the request
     prometheus_logger.litellm_request_total_latency_metric.labels.assert_called_once_with(
-        end_user="test_end_user",
-        hashed_api_key="key1",
-        api_key_alias="alias1",
-        requested_model="openai-gpt",
-        team="team1",
-        team_alias="team_alias1",
+        end_user=None,
         user="test_user",
+        hashed_api_key="test_hash",
+        api_key_alias="test_alias",
+        team="test_team",
+        team_alias="test_team_alias",
+        requested_model="openai-gpt",
         model="gpt-3.5-turbo",
     )
     prometheus_logger.litellm_request_total_latency_metric.labels().observe.assert_called_once_with(
@@ -849,3 +891,11 @@ def test_prometheus_factory(monkeypatch, disable_end_user_tracking):
         assert returned_dict["end_user"] == None
     else:
         assert returned_dict["end_user"] == "test_end_user"
+
+
+def test_get_tag_from_metadata(monkeypatch):
+    monkeypatch.setattr(
+        "litellm.custom_prometheus_metadata_labels", ["metadata.foo", "metadata.bar"]
+    )
+    metadata = {"foo": "bar", "bar": "baz", "taz": "qux"}
+    assert get_tag_from_metadata(metadata) == ["bar", "baz"]