fix: allow default empty vars for conditionals (#2570)

# What does this PR do?

We were not using conditionals correctly, conditionals can only be used
when the env variable is set, so `${env.ENVIRONMENT:+}` would return
None is ENVIRONMENT is not set.

If you want to create a conditional value, you need to do
`${env.ENVIRONMENT:=}`, this will pick the value of ENVIRONMENT if set,
otherwise will return None.

Closes: https://github.com/meta-llama/llama-stack/issues/2564

Signed-off-by: Sébastien Han <seb@redhat.com>

docs/source/distributions/configuration.md

@@ -125,7 +125,7 @@ config:
 ```
 
 If the environment variable is not set, the default value `http://localhost:11434` will be used.
-Empty defaults are not allowed so `url: ${env.OLLAMA_URL:=}` will raise an error if the environment variable is not set.
+Empty defaults are allowed so `url: ${env.OLLAMA_URL:=}` will be set to `None` if the environment variable is not set.
 
 #### Conditional Values
 
@@ -139,8 +139,10 @@ config:
 
 If the environment variable is set, the value after `:+` will be used. If it's not set, the field
 will be omitted with a `None` value.
-So `${env.ENVIRONMENT:+}` is supported, it means that the field will be omitted if the environment
-variable is not set. It can be used to make a field optional and then enabled at runtime when desired.
+
+Do not use conditional values (`${env.OLLAMA_URL:+}`) for empty defaults (`${env.OLLAMA_URL:=}`).
+This will be set to `None` if the environment variable is not set.
+Conditional must only be used when the environment variable is set.
 
 #### Examples
 

docs/source/providers/datasetio/remote_nvidia.md

@@ -16,7 +16,7 @@ NVIDIA's dataset I/O provider for accessing datasets from NVIDIA's data platform
 ## Sample Configuration
 
 ```yaml
-api_key: ${env.NVIDIA_API_KEY:+}
+api_key: ${env.NVIDIA_API_KEY:=}
 dataset_namespace: ${env.NVIDIA_DATASET_NAMESPACE:=default}
 project_id: ${env.NVIDIA_PROJECT_ID:=test-project}
 datasets_url: ${env.NVIDIA_DATASETS_URL:=http://nemo.test}

docs/source/providers/inference/remote_nvidia.md

@@ -17,7 +17,7 @@ NVIDIA inference provider for accessing NVIDIA NIM models and AI services.
 
 ```yaml
 url: ${env.NVIDIA_BASE_URL:=https://integrate.api.nvidia.com}
-api_key: ${env.NVIDIA_API_KEY:+}
+api_key: ${env.NVIDIA_API_KEY:=}
 append_api_version: ${env.NVIDIA_APPEND_API_VERSION:=True}
 
 ```

docs/source/providers/inference/remote_runpod.md

@@ -14,8 +14,8 @@ RunPod inference provider for running models on RunPod's cloud GPU platform.
 ## Sample Configuration
 
 ```yaml
-url: ${env.RUNPOD_URL:+}
-api_token: ${env.RUNPOD_API_TOKEN:+}
+url: ${env.RUNPOD_URL:=}
+api_token: ${env.RUNPOD_API_TOKEN:=}
 
 ```
 

docs/source/providers/inference/remote_together.md

@@ -15,7 +15,7 @@ Together AI inference provider for open-source models and collaborative AI devel
 
 ```yaml
 url: https://api.together.xyz/v1
-api_key: ${env.TOGETHER_API_KEY:+}
+api_key: ${env.TOGETHER_API_KEY:=}
 
 ```
 

docs/source/providers/inference/remote_watsonx.md

@@ -17,8 +17,8 @@ IBM WatsonX inference provider for accessing AI models on IBM's WatsonX platform
 
 ```yaml
 url: ${env.WATSONX_BASE_URL:=https://us-south.ml.cloud.ibm.com}
-api_key: ${env.WATSONX_API_KEY:+}
-project_id: ${env.WATSONX_PROJECT_ID:+}
+api_key: ${env.WATSONX_API_KEY:=}
+project_id: ${env.WATSONX_PROJECT_ID:=}
 
 ```
 

docs/source/providers/post_training/remote_nvidia.md

@@ -19,7 +19,7 @@ NVIDIA's post-training provider for fine-tuning models on NVIDIA's platform.
 ## Sample Configuration
 
 ```yaml
-api_key: ${env.NVIDIA_API_KEY:+}
+api_key: ${env.NVIDIA_API_KEY:=}
 dataset_namespace: ${env.NVIDIA_DATASET_NAMESPACE:=default}
 project_id: ${env.NVIDIA_PROJECT_ID:=test-project}
 customizer_url: ${env.NVIDIA_CUSTOMIZER_URL:=http://nemo.test}

docs/source/providers/scoring/inline_braintrust.md

@@ -13,7 +13,7 @@ Braintrust scoring provider for evaluation and scoring using the Braintrust plat
 ## Sample Configuration
 
 ```yaml
-openai_api_key: ${env.OPENAI_API_KEY:+}
+openai_api_key: ${env.OPENAI_API_KEY:=}
 
 ```
 

docs/source/providers/tool_runtime/remote_brave-search.md

@@ -14,7 +14,7 @@ Brave Search tool for web search capabilities with privacy-focused results.
 ## Sample Configuration
 
 ```yaml
-api_key: ${env.BRAVE_SEARCH_API_KEY:+}
+api_key: ${env.BRAVE_SEARCH_API_KEY:=}
 max_results: 3
 
 ```

docs/source/providers/tool_runtime/remote_tavily-search.md

@@ -14,7 +14,7 @@ Tavily Search tool for AI-optimized web search with structured results.
 ## Sample Configuration
 
 ```yaml
-api_key: ${env.TAVILY_SEARCH_API_KEY:+}
+api_key: ${env.TAVILY_SEARCH_API_KEY:=}
 max_results: 3
 
 ```

docs/source/providers/tool_runtime/remote_wolfram-alpha.md

@@ -13,7 +13,7 @@ Wolfram Alpha tool for computational knowledge and mathematical calculations.
 ## Sample Configuration
 
 ```yaml
-api_key: ${env.WOLFRAM_ALPHA_API_KEY:+}
+api_key: ${env.WOLFRAM_ALPHA_API_KEY:=}
 
 ```