diff --git a/llama_stack/distribution/resolver.py b/llama_stack/distribution/resolver.py
index 69a096e97..3abcc3772 100644
--- a/llama_stack/distribution/resolver.py
+++ b/llama_stack/distribution/resolver.py
@@ -127,6 +127,10 @@ async def resolve_impls(
 
         specs = {}
         for provider in providers:
+            if not provider.provider_id or provider.provider_id == "__disabled__":
+                log.warning(f"Provider `{provider.provider_type}` for API `{api}` is disabled")
+                continue
+
             if provider.provider_type not in provider_registry[api]:
                 raise ValueError(f"Provider `{provider.provider_type}` is not available for API `{api}`")
 
diff --git a/llama_stack/distribution/stack.py b/llama_stack/distribution/stack.py
index 1328c88ef..8f895e170 100644
--- a/llama_stack/distribution/stack.py
+++ b/llama_stack/distribution/stack.py
@@ -155,18 +155,34 @@ def replace_env_vars(config: Any, path: str = "") -> Any:
         return result
 
     elif isinstance(config, str):
-        pattern = r"\${env\.([A-Z0-9_]+)(?::([^}]*))?}"
+        # Updated pattern to support both default values (:) and conditional values (+)
+        pattern = r"\${env\.([A-Z0-9_]+)(?:([:\+])([^}]*))?}"
 
         def get_env_var(match):
             env_var = match.group(1)
-            default_val = match.group(2)
+            operator = match.group(2)  # ':' for default, '+' for conditional
+            value_expr = match.group(3)
 
-            value = os.environ.get(env_var)
-            if not value:
-                if default_val is None:
-                    raise EnvVarError(env_var, path)
+            env_value = os.environ.get(env_var)
+
+            if operator == ":":  # Default value syntax: ${env.FOO:default}
+                if not env_value:
+                    if value_expr is None:
+                        raise EnvVarError(env_var, path)
+                    else:
+                        value = value_expr
                 else:
-                    value = default_val
+                    value = env_value
+            elif operator == "+":  # Conditional value syntax: ${env.FOO+value_if_set}
+                if env_value:
+                    value = value_expr
+                else:
+                    # If env var is not set, return empty string for the conditional case
+                    value = ""
+            else:  # No operator case: ${env.FOO}
+                if not env_value:
+                    raise EnvVarError(env_var, path)
+                value = env_value
 
             # expand "~" from the values
             return os.path.expanduser(value)
diff --git a/llama_stack/providers/inline/vector_io/faiss/config.py b/llama_stack/providers/inline/vector_io/faiss/config.py
index 9eae9ed67..fa6e5bede 100644
--- a/llama_stack/providers/inline/vector_io/faiss/config.py
+++ b/llama_stack/providers/inline/vector_io/faiss/config.py
@@ -20,7 +20,7 @@ class FaissVectorIOConfig(BaseModel):
     kvstore: KVStoreConfig
 
     @classmethod
-    def sample_run_config(cls, __distro_dir__: str) -> Dict[str, Any]:
+    def sample_run_config(cls, __distro_dir__: str, **kwargs: Any) -> Dict[str, Any]:
         return {
             "kvstore": SqliteKVStoreConfig.sample_run_config(
                 __distro_dir__=__distro_dir__,
diff --git a/llama_stack/providers/remote/vector_io/chroma/config.py b/llama_stack/providers/remote/vector_io/chroma/config.py
index cbbfa9de3..3e2463252 100644
--- a/llama_stack/providers/remote/vector_io/chroma/config.py
+++ b/llama_stack/providers/remote/vector_io/chroma/config.py
@@ -13,5 +13,5 @@ class ChromaVectorIOConfig(BaseModel):
     url: str
 
     @classmethod
-    def sample_config(cls) -> Dict[str, Any]:
-        return {"url": "{env.CHROMADB_URL}"}
+    def sample_run_config(cls, url: str = "${env.CHROMADB_URL}", **kwargs: Any) -> Dict[str, Any]:
+        return {"url": url}
diff --git a/llama_stack/providers/remote/vector_io/pgvector/config.py b/llama_stack/providers/remote/vector_io/pgvector/config.py
index 7811de1ca..e9eb0f12d 100644
--- a/llama_stack/providers/remote/vector_io/pgvector/config.py
+++ b/llama_stack/providers/remote/vector_io/pgvector/config.py
@@ -4,6 +4,8 @@
 # This source code is licensed under the terms described in the LICENSE file in
 # the root directory of this source tree.
 
+from typing import Any, Dict
+
 from pydantic import BaseModel, Field
 
 from llama_stack.schema_utils import json_schema_type
@@ -16,3 +18,15 @@ class PGVectorVectorIOConfig(BaseModel):
     db: str = Field(default="postgres")
     user: str = Field(default="postgres")
     password: str = Field(default="mysecretpassword")
+
+    @classmethod
+    def sample_run_config(
+        cls,
+        host: str = "${env.PGVECTOR_HOST:localhost}",
+        port: int = "${env.PGVECTOR_PORT:5432}",
+        db: str = "${env.PGVECTOR_DB}",
+        user: str = "${env.PGVECTOR_USER}",
+        password: str = "${env.PGVECTOR_PASSWORD}",
+        **kwargs: Any,
+    ) -> Dict[str, Any]:
+        return {"host": host, "port": port, "db": db, "user": user, "password": password}
diff --git a/llama_stack/templates/dev/dev.py b/llama_stack/templates/dev/dev.py
index 694913119..e8aa31a7e 100644
--- a/llama_stack/templates/dev/dev.py
+++ b/llama_stack/templates/dev/dev.py
@@ -27,6 +27,8 @@ from llama_stack.providers.remote.inference.groq.config import GroqConfig
 from llama_stack.providers.remote.inference.groq.models import MODEL_ENTRIES as GROQ_MODEL_ENTRIES
 from llama_stack.providers.remote.inference.openai.config import OpenAIConfig
 from llama_stack.providers.remote.inference.openai.models import MODEL_ENTRIES as OPENAI_MODEL_ENTRIES
+from llama_stack.providers.remote.vector_io.chroma.config import ChromaVectorIOConfig
+from llama_stack.providers.remote.vector_io.pgvector.config import PGVectorVectorIOConfig
 from llama_stack.templates.template import DistributionTemplate, RunConfigSettings, get_model_registry
 
 
@@ -94,11 +96,27 @@ def get_distribution_template() -> DistributionTemplate:
     }
     name = "dev"
 
-    vector_io_provider = Provider(
-        provider_id="sqlite-vec",
-        provider_type="inline::sqlite-vec",
-        config=SQLiteVectorIOConfig.sample_run_config(f"distributions/{name}"),
-    )
+    vector_io_providers = [
+        Provider(
+            provider_id="sqlite-vec",
+            provider_type="inline::sqlite-vec",
+            config=SQLiteVectorIOConfig.sample_run_config(f"distributions/{name}"),
+        ),
+        Provider(
+            provider_id="${env.ENABLE_CHROMADB+chromadb}",
+            provider_type="remote::chromadb",
+            config=ChromaVectorIOConfig.sample_run_config(url="${env.CHROMADB_URL:}"),
+        ),
+        Provider(
+            provider_id="${env.ENABLE_PGVECTOR+pgvector}",
+            provider_type="remote::pgvector",
+            config=PGVectorVectorIOConfig.sample_run_config(
+                db="${env.PGVECTOR_DB:}",
+                user="${env.PGVECTOR_USER:}",
+                password="${env.PGVECTOR_PASSWORD:}",
+            ),
+        ),
+    ]
     embedding_provider = Provider(
         provider_id="sentence-transformers",
         provider_type="inline::sentence-transformers",
@@ -141,7 +159,7 @@ def get_distribution_template() -> DistributionTemplate:
             "run.yaml": RunConfigSettings(
                 provider_overrides={
                     "inference": inference_providers + [embedding_provider],
-                    "vector_io": [vector_io_provider],
+                    "vector_io": vector_io_providers,
                 },
                 default_models=default_models + [embedding_model],
                 default_tool_groups=default_tool_groups,
diff --git a/llama_stack/templates/dev/run.yaml b/llama_stack/templates/dev/run.yaml
index f1d72d572..71fbcb353 100644
--- a/llama_stack/templates/dev/run.yaml
+++ b/llama_stack/templates/dev/run.yaml
@@ -42,6 +42,18 @@ providers:
     provider_type: inline::sqlite-vec
     config:
       db_path: ${env.SQLITE_STORE_DIR:~/.llama/distributions/dev}/sqlite_vec.db
+  - provider_id: ${env.ENABLE_CHROMADB+chromadb}
+    provider_type: remote::chromadb
+    config:
+      url: ${env.CHROMADB_URL:}
+  - provider_id: ${env.ENABLE_PGVECTOR+pgvector}
+    provider_type: remote::pgvector
+    config:
+      host: ${env.PGVECTOR_HOST:localhost}
+      port: ${env.PGVECTOR_PORT:5432}
+      db: ${env.PGVECTOR_DB:}
+      user: ${env.PGVECTOR_USER:}
+      password: ${env.PGVECTOR_PASSWORD:}
   safety:
   - provider_id: llama-guard
     provider_type: inline::llama-guard
diff --git a/llama_stack/templates/sambanova/run.yaml b/llama_stack/templates/sambanova/run.yaml
index 124d11baf..cfa0cc194 100644
--- a/llama_stack/templates/sambanova/run.yaml
+++ b/llama_stack/templates/sambanova/run.yaml
@@ -22,12 +22,18 @@ providers:
         type: sqlite
         namespace: null
         db_path: ${env.SQLITE_STORE_DIR:~/.llama/distributions/sambanova}/faiss_store.db
-  - provider_id: chromadb
+  - provider_id: ${env.ENABLE_CHROMADB+chromadb}
     provider_type: remote::chromadb
-    config: {}
-  - provider_id: pgvector
+    config:
+      url: ${env.CHROMADB_URL:}
+  - provider_id: ${env.ENABLE_PGVECTOR+pgvector}
     provider_type: remote::pgvector
-    config: {}
+    config:
+      host: ${env.PGVECTOR_HOST:localhost}
+      port: ${env.PGVECTOR_PORT:5432}
+      db: ${env.PGVECTOR_DB:}
+      user: ${env.PGVECTOR_USER:}
+      password: ${env.PGVECTOR_PASSWORD:}
   safety:
   - provider_id: llama-guard
     provider_type: inline::llama-guard
diff --git a/llama_stack/templates/sambanova/sambanova.py b/llama_stack/templates/sambanova/sambanova.py
index 0a0b6bd7e..08c3a54cc 100644
--- a/llama_stack/templates/sambanova/sambanova.py
+++ b/llama_stack/templates/sambanova/sambanova.py
@@ -11,8 +11,11 @@ from llama_stack.distribution.datatypes import (
     ShieldInput,
     ToolGroupInput,
 )
+from llama_stack.providers.inline.vector_io.faiss.config import FaissVectorIOConfig
 from llama_stack.providers.remote.inference.sambanova import SambaNovaImplConfig
 from llama_stack.providers.remote.inference.sambanova.models import MODEL_ENTRIES
+from llama_stack.providers.remote.vector_io.chroma.config import ChromaVectorIOConfig
+from llama_stack.providers.remote.vector_io.pgvector.config import PGVectorVectorIOConfig
 from llama_stack.templates.template import DistributionTemplate, RunConfigSettings, get_model_registry
 
 
@@ -38,6 +41,30 @@ def get_distribution_template() -> DistributionTemplate:
         config=SambaNovaImplConfig.sample_run_config(),
     )
 
+    vector_io_providers = [
+        Provider(
+            provider_id="faiss",
+            provider_type="inline::faiss",
+            config=FaissVectorIOConfig.sample_run_config(
+                __distro_dir__=f"distributions/{name}",
+            ),
+        ),
+        Provider(
+            provider_id="${env.ENABLE_CHROMADB+chromadb}",
+            provider_type="remote::chromadb",
+            config=ChromaVectorIOConfig.sample_run_config(url="${env.CHROMADB_URL:}"),
+        ),
+        Provider(
+            provider_id="${env.ENABLE_PGVECTOR+pgvector}",
+            provider_type="remote::pgvector",
+            config=PGVectorVectorIOConfig.sample_run_config(
+                db="${env.PGVECTOR_DB:}",
+                user="${env.PGVECTOR_USER:}",
+                password="${env.PGVECTOR_PASSWORD:}",
+            ),
+        ),
+    ]
+
     available_models = {
         name: MODEL_ENTRIES,
     }
@@ -69,6 +96,7 @@ def get_distribution_template() -> DistributionTemplate:
             "run.yaml": RunConfigSettings(
                 provider_overrides={
                     "inference": [inference_provider],
+                    "vector_io": vector_io_providers,
                 },
                 default_models=default_models,
                 default_shields=[ShieldInput(shield_id="meta-llama/Llama-Guard-3-8B")],
diff --git a/tests/test_replace_env_vars.py b/tests/test_replace_env_vars.py
new file mode 100644
index 000000000..7fcbbfde9
--- /dev/null
+++ b/tests/test_replace_env_vars.py
@@ -0,0 +1,66 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the terms described in the LICENSE file in
+# the root directory of this source tree.
+
+import os
+import unittest
+
+from llama_stack.distribution.stack import replace_env_vars
+
+
+class TestReplaceEnvVars(unittest.TestCase):
+    def setUp(self):
+        # Clear any existing environment variables we'll use in tests
+        for var in ["TEST_VAR", "EMPTY_VAR", "ZERO_VAR"]:
+            if var in os.environ:
+                del os.environ[var]
+
+        # Set up test environment variables
+        os.environ["TEST_VAR"] = "test_value"
+        os.environ["EMPTY_VAR"] = ""
+        os.environ["ZERO_VAR"] = "0"
+
+    def test_simple_replacement(self):
+        self.assertEqual(replace_env_vars("${env.TEST_VAR}"), "test_value")
+
+    def test_default_value_when_not_set(self):
+        self.assertEqual(replace_env_vars("${env.NOT_SET:default}"), "default")
+
+    def test_default_value_when_set(self):
+        self.assertEqual(replace_env_vars("${env.TEST_VAR:default}"), "test_value")
+
+    def test_default_value_when_empty(self):
+        self.assertEqual(replace_env_vars("${env.EMPTY_VAR:default}"), "default")
+
+    def test_conditional_value_when_set(self):
+        self.assertEqual(replace_env_vars("${env.TEST_VAR+conditional}"), "conditional")
+
+    def test_conditional_value_when_not_set(self):
+        self.assertEqual(replace_env_vars("${env.NOT_SET+conditional}"), "")
+
+    def test_conditional_value_when_empty(self):
+        self.assertEqual(replace_env_vars("${env.EMPTY_VAR+conditional}"), "")
+
+    def test_conditional_value_with_zero(self):
+        self.assertEqual(replace_env_vars("${env.ZERO_VAR+conditional}"), "conditional")
+
+    def test_mixed_syntax(self):
+        self.assertEqual(replace_env_vars("${env.TEST_VAR:default} and ${env.NOT_SET+conditional}"), "test_value and ")
+        self.assertEqual(
+            replace_env_vars("${env.NOT_SET:default} and ${env.TEST_VAR+conditional}"), "default and conditional"
+        )
+
+    def test_nested_structures(self):
+        data = {
+            "key1": "${env.TEST_VAR:default}",
+            "key2": ["${env.NOT_SET:default}", "${env.TEST_VAR+conditional}"],
+            "key3": {"nested": "${env.NOT_SET+conditional}"},
+        }
+        expected = {"key1": "test_value", "key2": ["default", "conditional"], "key3": {"nested": ""}}
+        self.assertEqual(replace_env_vars(data), expected)
+
+
+if __name__ == "__main__":
+    unittest.main()