[Test/sample] Fix the model version in kubeflow_tf_serving sample to avoid potential conflict.

[numerology]

When there is no new commit detected in a PR, PULL_PULL_SHA will be reused, causing conflict in the export model path.

This can be fixed by using timestamp as the version number. See #2047 for context.

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This change is 

[gaoning777]

Adding the randomization in the sample itself is not a good practice. It's supposed to be the sample test infra's work to pass in different model names due to cluster sharing among test retries.

Could we start with a placeholder implementation? since the model name as well as the input/output could potentially use this placeholder.

[gaoning777]

However, to unblock the team, we can merge this one now.
Could you create an issue?
/lgtm

[numerology]

Adding the randomization in the sample itself is not a good practice. It's supposed to be the sample test infra's work to pass in different model names due to cluster sharing among test retries.

Could we start with a placeholder implementation? since the model name as well as the input/output could potentially use this placeholder.

For the placeholder, I have two options in mind:

1. short term: we can dynamically replace some parameters to inject the notebook in sample test infra;
2. long term: switch to jsonnet for test config files.

Shall we begin with the first one to unblock things?

[gaoning777]

That sounds great. We can start with two placeholders: TIMESTAMP and COMMITTAG.
e.g.
test_name: kubeflow_tf_serving
notebook_params:
output: gs://ml-pipeline-test/${COMMITTAG}
project: ml-pipeline-test
experiment_name: kubeflow_tf_serving-test
model_name: model-${TIMESTAMP}

becomes
test_name: kubeflow_tf_serving
notebook_params:
output: gs://ml-pipeline-test/a86ee2dfbb20c67964130ec132c304bb3eaa010e
project: ml-pipeline-test
experiment_name: kubeflow_tf_serving-test
model_name: model-1568914870

[numerology]

That sounds great. We can start with two placeholders: TIMESTAMP and COMMITTAG.
e.g.
test_name: kubeflow_tf_serving
notebook_params:
output: gs://ml-pipeline-test/${COMMITTAG}
project: ml-pipeline-test
experiment_name: kubeflow_tf_serving-test
model_name: model-${TIMESTAMP}

becomes
test_name: kubeflow_tf_serving
notebook_params:
output: gs://ml-pipeline-test/a86ee2dfbb20c67964130ec132c304bb3eaa010e
project: ml-pipeline-test
experiment_name: kubeflow_tf_serving-test
model_name: model-1568914870

Sounds good, can you help me approve plz? Thanks.

[gaoning777]

/approve

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[gaoning777]

Please link the issue you created here to keep in track.

[numerology]

Please link the issue you created here to keep in track.

Triaging issue #2171