Send variables parameter as a Hash to the Prometheus proxy API

Merged Reuben Pereira requested to merge 218312-change-variables-parameter-format into master

What does this MR do?

Our Prometheus proxy GET API currently accepts the variables query parameter as an array. Unfortunately, we have observed that the order of elements in the array can be changed by components between the frontend and backend.

In the backend, an array like ['variable1', 'value1', 'variable2', 'value2'] is transformed into a Hash {'variable1' => 'value1', 'variable2' => 'value2'}.

To avoid the problems caused by inconsistent ordering of elements, we are now changing the format of the variables query parameter to a Hash.

Before After
variables[]=key1
variables[]=value1
variables[]=key2
variables[]=value2
variables[key1]=value1
variables[key2]=value2

Mentions: #219179 (closed)

The confidential issue where we did the research #218312

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Does this MR meet the acceptance criteria?

Conformity

Availability and Testing

Security

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  • Label as security and @ mention @gitlab-com/gl-security/appsec
  • The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
  • Security reports checked/validated by a reviewer from the AppSec team
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