Currently, the symptom, diagnoses and action tables do not include logical entries for when symptoms, diagnoses and actions are not generated by the current policy invocation. This make it difficult to filter the tables using real time or checkpoints and ensure correctness.

Adds a standalone Dhalion process that initiates the Dhalion configurations from a user-provided yaml file and invokes the policy executor.

Add a link to the usage documentation in the README

CVE-2017-18640

Recommended upgrade version：
1.26

The following error is observed when one of the parameters is Instant.MIN

Caused by: java.lang.ArithmeticException: long overflow
    at java.lang.Math.multiplyExact(Math.java:892)
    at java.time.Instant.toEpochMilli(Instant.java:1237)
    at com.microsoft.dhalion.core.TableUtils.filterTime(TableUtils.java:42)
    at com.microsoft.dhalion.core.OutcomeTable.filterTime(OutcomeTable.java:110)
    at com.microsoft.dhalion.core.SymptomsTable.between(SymptomsTable.java:109)

At present, metrics provider doesn't cache results. We should expose a metrics provider interface which adds support for caching and makes actual api calls only when it is required.

Problem
HealthManager class creates the injector instance and tries to create the metrics provider class using this. What this means is that the metrics provider constructor must itself depend on a lot of concrete dependencies.

1. This makes testing difficult.
2. We cannot use annotation binding in our classes.
   There are probably more such disadvantages.

Example
Consider the following definition.

@Inject
public BasicPolicy(Config sysConfig, Dependency1 dep1){

Here Dependency1 must be a concrete class (with its own inject annotations) for health manager to properly create its instance. There could be a workaround by having it as Dependency1Factory however this is again concrete and defeats the purpose of DI.

Ask
Provide a mechanism to register user defined modules in the HealthManager. For example. an IPolicyBindings with getBindings() getModules() and then that can be applied to the injector by the HealthManager class before attempting to create the metrics provider instance.

see apache/incubator-heron#2927

Incorporate configuration builder generic configuration classes that will be populated based on user-provided yaml files.

Dhalion implementations often require max, min, average, etc, grouped by components. For e.g. component trend computation.

We have seen many invocations of sort-by-time method followed by last method. This could be replaced by a utility method, say latest, to simplify the usage.

The users should be able to query the tables using either the epoch notion or the actual time.

Right now, in Dhalion, we can provide only single metrics provider. This becomes limiting when we want to implement policy for Spark which will require metrics of both Yarn as well as Spark.

There are important files that Microsoft projects should all have that are not present in this repository. A pull request has been opened to add the missing file(s). When the pr is merged this issue will be closed automatically.

Microsoft teams can learn more about this effort and share feedback within the open source guidance available internally.

Merge this pull request

Dhalion can be used for offline analysis using archived metrics. In such cases, the policy execution checkpoint should refer to a time in the past, the time at which the metrics were collected. So instead of using the current time as default checkpoint, let the policy itself provide a checkpoint.