METRON-2148: Stellar REST POST function

[merrimanr]

Contributor Comments

This PR adds a REST_POST Stellar function with syntax and options similar to the existing REST_GET function for performing REST POST requests. A Stellar map can now be passed into the function and added to the request as query parameters (this feature was added to REST_GET as well). Separate global configs were added for REST_GET and REST_POST in addition to the existing global config for REST functions. For REST_POST requests, there is also an option enforce.json that ensures POST data is well-formed JSON.

Changes Included

• REST_POST Stellar function was added to RestFunctions class.
• RestFunctions class was refactored by moving common code used by REST_GET and REST_POST to their own methods. Now code specific to either functions mostly consists of argument parsing and request building.
• Unit and integration tests were moved to separate tests. The RestFunctions class should be 100% covered.
• Documentation added for the new REST_POST function and additional options added to both.

Testing

This has been tested in full dev. Since there were significant changes to RestFunctions I regression tested using the test instructions in original Stellar Rest PR. Note a regression was introduced when using the REST_GET function in the enrichment topology (class version error). This is being addressed here.

In addition to this I also followed these instructions:

1. Assuming full dev has already been spun up during regression testing described above, start the Stellar shell with /usr/metron/0.7.2/bin/stellar --zookeeper node1:2181.

2. Defined a variable to hold POST data:

[Stellar]>>> data := {'key':'value'}
{key=value}

3. Send a POST request to a test service (httpbin.org in this example):

[Stellar]>>> REST_POST('http://httpbin.org/post', data)
{args={}, data={"key":"value"}, files={}, form={}, headers={Accept=application/json, Accept-Encoding=gzip,deflate, Content-Length=15, Content-Type=application/json, Host=httpbin.org, User-Agent=Apache-HttpClient/4.3.2 (java 1.5)}, json={key=value}, origin=136.49.31.47, 136.49.31.47, url=https://httpbin.org/post}

The request should succeed with the correct POST data in the response.

4. Define a variable to hold query parameters:

[Stellar]>>> params := {'param1': 'value1', 'param2': 'value2'}
{param1=value1, param2=value2}

5. Send a POST request, passing in the query parameter variable:

[Stellar]>>> REST_POST('http://httpbin.org/post', data, {}, params)
{args={param1=value1, param2=value2}, data={"key":"value"}, files={}, form={}, headers={Accept=application/json, Accept-Encoding=gzip,deflate, Content-Length=15, Content-Type=application/json, Host=httpbin.org, User-Agent=Apache-HttpClient/4.3.2 (java 1.5)}, json={key=value}, origin=136.49.31.47, 136.49.31.47, url=https://httpbin.org/post?param1=value1&param2=value2}

The args and url attributes in the response should contain the query parameters.

6. Test configuration priority by changing the empty response override in various configs. First enable 404 responses and set an override:

%define stellar.rest.settings := {'response.codes.allowed': [200, 404],  'empty.content.override': {}}
[Stellar]>>> REST_POST('http://httpbin.org/status/404', data)
{}

The response should match the override value set in the config.

7. Configure the override for all REST functions:

[Stellar]>>> REST_POST('http://httpbin.org/status/404', data)
global rest config

The response should match the global override value set in the config.

8. Configure the override for REST_POST functions:

[Stellar]>>> %define stellar.rest.post.settings := {'empty.content.override': 'rest post config'}
{empty.content.override=rest post config}
[Stellar]>>> REST_POST('http://httpbin.org/status/404', data)
rest post config

The response should match the rest post override value set in the config.

9 Configure the override in a variable that will be passed to the function:

[Stellar]>>> config := {'empty.content.override': 'function config'}
{empty.content.override=function config}
[Stellar]>>> REST_POST('http://httpbin.org/status/404', data, config)
function config

The response should match the override in the config passed to the function.

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[ottobackwards]

This is cool, but wouldn't https support be needed for real world application?

[ottobackwards]

I understand that if GET doesn't have it, then we've already decided to put that off, but do we have a plan?

[merrimanr]

I will do some research into adding SSL support, maybe it's a minimal amount of extra code. I would prefer to add that incrementally in a separate PR since code reviews seem to go faster when split into smaller units of work. I think REST POST support without SSL is an improvement on it's own.

[ottobackwards]

Having worked with the nifi SSL Controller Service, it isn't a small thing. but it is important. I'm fine with doing it later, but please create an investigate jira or something to link to this, so if someone wants to they can pick it up

[mmiklavc]

@merrimanr - did we ever get a Jira for the follow-on @ottobackwards mentioned? Can you link it back here in the comments as well as link it with the Jira for this PR (ie add a "relates-to" relationship to this Jira and the one for REST_GET)?

[merrimanr]

@ottobackwards here is the SSL Jira: https://issues.apache.org/jira/browse/METRON-2165. Feel free to add any requirements you want.

[mmiklavc]

Only one potential issue stands out to me here, nice work @merrimanr.

[mmiklavc]

Why do we need to manage timeouts on our end? e.g. https://www.baeldung.com/httpclient-timeout

[merrimanr]

From the link you reference:

HttpClient doesn’t have any configuration that allows us to set an overall timeout for a request; it does, however, provide abort functionality for requests, so we can leverage that mechanism to implement a simple timeout mechanism:

[mmiklavc]

+1 by inspection, thanks @merrimanr!