https://gitlab.com/gitlab-org/gitlab-ce/issues/62971

Adds support to EnvironmentsController#metrics_dashboard
for the following params: group, title, y_label
These params are used to uniquely identify a panel on
the metrics dashboard.

Metrics are stored in several places, so this adds
utilities to find a specific panel from the database
or filesystem depending on the metric specified.

Also moves some shared utilities into separate classes,
notably default values and errors.

Sarah Yasonik authored 5 years ago and Thong Kuah committed 5 years ago

In preparation for embedding specific metrics in issues
https://gitlab.com/gitlab-org/gitlab-ce/issues/62971,
this commit moves the BaseService for metrics dashboards
to a new services subdirectory. This is purely for the sake
of organization and maintainability.

Adds permission checks to the metrics_dashboard endpoint. Users
with role of Reporter or above should have access to view the
metrics for a given project.

This commits adds support for metrics dashboards
for embedding. If the flag 'embedded' is provided
to the environments/id/metrics_dashboard endpoint,
the response will be suitable for embedding in
issues or other content.

This is a precursor for support for embedding
metrics in GFM.

Error classes associated with individual stages of
dashboard processing tend to have very long names.
As dashboard post-processing includes more steps,
we will likely need to handle more error cases.
Refactoring to have all errors inherit from a specific
base class will help accommodate this and keep the code
more readable.

Adds a new stage to dashboard processesing step for the
EnvironmentsController::metrics_dashboard endpoint.

Allows the front end to avoid generating the endpoint
unitutive string mutations.

Updates the EnvironmentController#metrics_dashboard endpoint
to support a "dashboard" param, which can be used to specify
the filepath of a dashboard configuration from a project
repository. Dashboard configurations are expected to be
stored in .gitlab/dashboards/.

Updates dashboard post-processing steps to exclude custom
metrics, which should only display on the system dashboard.