Restore deprecated environment variable for backward compatibility (#292

)

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**What this PR does / why we need it**:

`MODEL_NAME` & `prometheus_multiproc_dir` env var was removed in this PR
#276 . However, we'll restore it for
now to give time to user for migrating to the new environment variable
(CARAML_MODEL_FULLNAME).

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the problem you're trying to solve. --->

**Which issue(s) this PR fixes**:
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Fixes #

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**Checklist**

- [x] Added unit test, integration, and/or e2e tests
- [x] Tested locally
- [ ] Updated documentation
- [ ] Update Swagger spec if the PR introduce API changes
- [ ] Regenerated Golang and Python client if the PR introduce API
changes

Signed-off-by: Pradithya Aria <[email protected]>

api/cluster/resource/templater.go

@@ -44,6 +44,7 @@ const (
 	envTransformerModelName  = "MERLIN_TRANSFORMER_MODEL_NAME"
 	envTransformerPredictURL = "MERLIN_TRANSFORMER_MODEL_PREDICT_URL"
 
+	envPyFuncModelName           = "MODEL_NAME"
 	envPredictorPort             = "MERLIN_PREDICTOR_PORT"
 	envPredictorModelName        = "MERLIN_MODEL_NAME"
 	envPredictorArtifactLocation = "MERLIN_ARTIFACT_LOCATION"
@@ -579,6 +580,10 @@ func createCustomPredictorSpec(modelService *models.Service, resources corev1.Re
 // createPyFuncDefaultEnvVars return default env vars for Pyfunc model.
 func createPyFuncDefaultEnvVars(svc *models.Service) models.EnvVars {
 	envVars := models.EnvVars{
+		models.EnvVar{
+			Name:  envPyFuncModelName,
+			Value: models.CreateInferenceServiceName(svc.ModelName, svc.ModelVersion),
+		},
 		models.EnvVar{
 			Name:  envModelName,
 			Value: svc.ModelName,

api/cluster/resource/templater_test.go

@@ -3377,6 +3377,10 @@ func getLimit(quantity resource.Quantity) resource.Quantity {
 
 func createPyFuncDefaultEnvVarsWithProtocol(svc *models.Service, protocolValue protocol.Protocol) models.EnvVars {
 	envVars := models.EnvVars{
+		models.EnvVar{
+			Name:  envPyFuncModelName,
+			Value: models.CreateInferenceServiceName(svc.ModelName, svc.ModelVersion),
+		},
 		models.EnvVar{
 			Name:  envModelName,
 			Value: svc.ModelName,

python/pyfunc-server/base.Dockerfile

@@ -23,4 +23,6 @@ RUN conda env create -f /pyfunc-server/environment.yaml && \
     rm -rf /root/.cache
 
 RUN mkdir /prom_dir
-ENV PROMETHEUS_MULTIPROC_DIR=/prom_dir
+ENV PROMETHEUS_MULTIPROC_DIR=/prom_dir
+# For backward compatibility
+ENV prometheus_multiproc_dir=/prom_dir