External constants support (#163)

(cherry picked from commit 096780a)

Author: 1vn

docs/applications/advanced/external-models.md

@@ -23,7 +23,7 @@ $ aws s3 cp model.zip s3://your-bucket/model.zip
 - kind: api
   name: my-api
   external_model:
-    path: s3://your-bucket/model.zip
+    path: s3://my-bucket/model.zip
     region: us-west-2
   compute:
     replicas: 5

docs/applications/resources/apis.md

@@ -9,8 +9,8 @@ Serve models at scale and use them to build smarter applications.
   name: <string>  # API name (required)
   model: <string>  # reference to a Cortex model (this or external_model must be specified)
   external_model:  # (this or model must be specified)
-    path: <string>  # path to a zipped model dir
-    region: <string> # S3 region (default: us-west-2)
+    path: <string>  # path to a zipped model dir (e.g. s3://my-bucket/model.zip)
+    region: <string>  # S3 region (default: us-west-2)
   compute:
     replicas: <int>  # number of replicas to launch (default: 1)
     cpu: <string>  # CPU request (default: Null)

docs/applications/resources/constants.md

@@ -8,7 +8,11 @@ Constants represent literal values which can be used in other Cortex resources.
 - kind: constant
   name: <string>  # constant name (required)
   type: <output_type>  # the type of the constant (optional, will be inferred from value if not specified)
-  value: <output_value>  # a literal value (required)
+  value: <output_value>  # a literal value (this or external_model must be specified)
+  external_model:  # (this or value must be specified)
+    path: <string>  # path to a JSON object (e.g. s3://my-bucket/constant.json)
+    region: <string>  # S3 region (default: us-west-2)
+
 ```
 
 See [Data Types](data-types.md) for details about output types and values.

docs/applications/resources/environments.md

@@ -26,7 +26,7 @@ Transfer data at scale from data warehouses like S3 into the Cortex environment.
 data:
   type: csv  # file type (required)
   path: s3a://<bucket_name>/<file_name>  # S3 is currently supported (required)
-  region: us-west-2 # S3 region (default: us-west-2)
+  region: us-west-2  # S3 region (default: us-west-2)
   drop_null: <bool>  # drop any rows that contain at least 1 null value (default: false)
   csv_config: <csv_config>  # optional configuration that can be provided
   schema:
@@ -65,7 +65,7 @@ csv_config:
 data:
   type: parquet  # file type (required)
   path: s3a://<bucket_name>/<file_name>  # S3 is currently supported (required)
-  region: us-west-2 # S3 region (default: us-west-2)
+  region: us-west-2  # S3 region (default: us-west-2)
   drop_null: <bool>  # drop any rows that contain at least 1 null value (default: false)
   schema:
     - parquet_column_name: <string>  # name of the column in the parquet file (required)

pkg/operator/api/userconfig/apis.go

@@ -119,7 +119,7 @@ func (api *API) Validate() error {
 		}
 
 		if ok, err := aws.IsS3FileExternal(bucket, key, api.ExternalModel.Region); err != nil || !ok {
-			return errors.Wrap(ErrorExternalModelNotFound(api.ExternalModel.Path), Identify(api), ExternalModelKey, PathKey)
+			return errors.Wrap(ErrorExternalNotFound(api.ExternalModel.Path), Identify(api), ExternalModelKey, PathKey)
 		}
 	}
 

pkg/operator/api/userconfig/config_key.go

@@ -27,6 +27,7 @@ const (
 	PathKey       = "path"
 	OutputTypeKey = "output_type"
 	TagsKey       = "tags"
+	ExternalKey   = "external"
 
 	// input schema options
 	OptionalOptKey = "_optional"

pkg/operator/api/userconfig/constants.go

@@ -17,6 +17,7 @@ limitations under the License.
 package userconfig
 
 import (
+	"github.com/cortexlabs/cortex/pkg/lib/aws"
 	cr "github.com/cortexlabs/cortex/pkg/lib/configreader"
 	"github.com/cortexlabs/cortex/pkg/lib/errors"
 	"github.com/cortexlabs/cortex/pkg/operator/api/resource"
@@ -26,9 +27,10 @@ type Constants []*Constant
 
 type Constant struct {
 	ResourceFields
-	Type  OutputSchema `json:"type" yaml:"type"`
-	Value interface{}  `json:"value" yaml:"value"`
-	Tags  Tags         `json:"tags" yaml:"tags"`
+	Type     OutputSchema      `json:"type" yaml:"type"`
+	Value    interface{}       `json:"value" yaml:"value"`
+	Tags     Tags              `json:"tags" yaml:"tags"`
+	External *ExternalConstant `json:"external" yaml:"external"`
 }
 
 var constantValidation = &cr.StructValidation{
@@ -50,14 +52,43 @@ var constantValidation = &cr.StructValidation{
 		{
 			StructField: "Value",
 			InterfaceValidation: &cr.InterfaceValidation{
-				Required: true,
+				Required: false,
 			},
 		},
+		{
+			StructField:      "External",
+			StructValidation: externalModelFieldValidation,
+		},
 		tagsFieldValidation,
 		typeFieldValidation,
 	},
 }
 
+type ExternalConstant struct {
+	Path   string `json:"path" yaml:"path"`
+	Region string `json:"region" yaml:"region"`
+}
+
+var externalConstantFieldValidation = &cr.StructValidation{
+	DefaultNil: true,
+	StructFieldValidations: []*cr.StructFieldValidation{
+		{
+			StructField: "Path",
+			StringValidation: &cr.StringValidation{
+				Validator: cr.GetS3PathValidator(),
+				Required:  true,
+			},
+		},
+		{
+			StructField: "Region",
+			StringValidation: &cr.StringValidation{
+				Default:       aws.DefaultS3Region,
+				AllowedValues: aws.S3Regions.Slice(),
+			},
+		},
+	},
+}
+
 func (constants Constants) Validate() error {
 	for _, constant := range constants {
 		if err := constant.Validate(); err != nil {
@@ -79,6 +110,25 @@ func (constants Constants) Validate() error {
 }
 
 func (constant *Constant) Validate() error {
+	if constant.External == nil && constant.Value == nil {
+		return errors.Wrap(ErrorSpecifyOnlyOneMissing(ValueKey, ExternalKey), Identify(constant))
+	}
+
+	if constant.External != nil && constant.Value != nil {
+		return errors.Wrap(ErrorSpecifyOnlyOne(ValueKey, ExternalKey), Identify(constant))
+	}
+
+	if constant.External != nil {
+		bucket, key, err := aws.SplitS3Path(constant.External.Path)
+		if err != nil {
+			return errors.Wrap(err, Identify(constant), ExternalKey, PathKey)
+		}
+
+		if ok, err := aws.IsS3FileExternal(bucket, key, constant.External.Region); err != nil || !ok {
+			return errors.Wrap(ErrorExternalNotFound(constant.External.Path), Identify(constant), ExternalKey, PathKey)
+		}
+	}
+
 	if constant.Type != nil {
 		castedValue, err := CastOutputValue(constant.Value, constant.Type)
 		if err != nil {

pkg/operator/api/userconfig/errors.go

@@ -75,7 +75,7 @@ const (
 	ErrEnvSchemaMismatch
 	ErrExtraResourcesWithExternalAPIs
 	ErrImplDoesNotExist
-	ErrExternalModelNotFound
+	ErrExternalNotFound
 )
 
 var errorKinds = []string{
@@ -125,10 +125,10 @@ var errorKinds = []string{
 	"err_env_schema_mismatch",
 	"err_extra_resources_with_external_a_p_is",
 	"err_impl_does_not_exist",
-	"err_external_model_not_found",
+	"err_external_not_found",
 }
 
-var _ = [1]int{}[int(ErrExternalModelNotFound)-(len(errorKinds)-1)] // Ensure list length matches
+var _ = [1]int{}[int(ErrExternalNotFound)-(len(errorKinds)-1)] // Ensure list length matches
 
 func (t ErrorKind) String() string {
 	return errorKinds[t]
@@ -578,9 +578,9 @@ func ErrorImplDoesNotExist(path string) error {
 	}
 }
 
-func ErrorExternalModelNotFound(path string) error {
+func ErrorExternalNotFound(path string) error {
 	return Error{
-		Kind:    ErrExternalModelNotFound,
+		Kind:    ErrExternalNotFound,
 		message: fmt.Sprintf("%s: file not found or inaccessible", path),
 	}
 }

pkg/workloads/lib/context.py

@@ -441,7 +441,12 @@ def populate_values(self, input, input_schema, preserve_column_refs):
         if util.is_resource_ref(input):
             res_name = util.get_resource_ref(input)
             if res_name in self.constants:
-                const_val = self.constants[res_name]["value"]
+                if self.constants[res_name]["value"]:
+                    const_val = self.constants[res_name]["value"]
+                elif self.constants[res_name]["external"]:
+                    const_val = self.storage.get_json_external(
+                        self.constants[res_name]["external"]["path"]
+                    )
                 try:
                     return self.populate_values(const_val, input_schema, preserve_column_refs)
                 except CortexException as e:

pkg/workloads/lib/storage/s3.py

@@ -114,9 +114,12 @@ def _get_matching_s3_keys_generator(self, prefix="", suffix=""):
     def _upload_string_to_s3(self, string, key):
         self.s3.put_object(Bucket=self.bucket, Key=key, Body=string)
 
-    def _read_bytes_from_s3(self, key, allow_missing=False):
+    def _read_bytes_from_s3(self, key, allow_missing=False, ext_bucket=None):
         try:
-            byte_array = self.s3.get_object(Bucket=self.bucket, Key=key)["Body"].read()
+            bucket = self.bucket
+            if ext_bucket is not None:
+                bucket = ext_bucket
+            byte_array = self.s3.get_object(Bucket=bucket, Key=key)["Body"].read()
         except self.s3.exceptions.NoSuchKey as e:
             if allow_missing:
                 return None
@@ -190,3 +193,13 @@ def download_file_external(self, s3_path, local_path):
             return local_path
         except Exception as e:
             raise CortexException("bucket " + bucket, "key " + key) from e
+
+    def get_json_external(self, s3_path):
+        try:
+            bucket, key = self.deconstruct_s3_path(s3_path)
+            obj = self._read_bytes_from_s3(key, ext_bucket=bucket)
+            if obj is None:
+                return None
+            return json.loads(obj.decode("utf-8"))
+        except Exception as e:
+            raise CortexException("bucket " + bucket, "key " + key) from e