Signed-off-by: NRémy Coutable <remy@rymai.me>

This change adds three new instrumentations, driven through rails
notifications: render_template.action_view,
render_collection.action_view and render_partial.action_view.

These can help developers understand why renders are taking a long
time which may in turn help them to improve their performance.

http_max_redirects was introduced in 4.2.2, so upgrade kubeclient.

The monkey-patch was global so we will have to check that all instances
of Kubeclient::Client are handled.

Spec all methods of KubeClient

This should provide better confidence that we are indeed disallowing
redirection in all cases

Signed-off-by: NRémy Coutable <remy@rymai.me>

This change will publish distributed tracing spans related to
SQL ActiveRecord queries. These queries are unbound, so will still
contain parameter substitution strings in place of actual parameter
values.

This ensures that the SQL strings do not need to be scrubbed, since the
values are not included in the SQL.

More details of rails instrumentation can be found here:
https://guides.rubyonrails.org/active_support_instrumentation.html

Signed-off-by: NRémy Coutable <remy@rymai.me>

This change allows the GitLab rails and sidekiq components to receive
tracing spans from upstream services such as Workhorse and pass these
spans on to downstream services including Gitaly and Sidekiq.

This change will also emit traces for incoming and outgoing requests
using the propagated trace information. This will allow operators and
engineers to view traces across the Workhorse, GitLab Rails, Sidekiq and
Gitaly components.

Additional intra-service instrumentation will be added in future
changes.

This change will instantiate an OpenTracing tracer and configure it
as the global tracer when the GITLAB_TRACING environment variable is
configured. GITLAB_TRACING takes a "connection string"-like value,
encapsulating the driver (eg jaeger, etc) and options for the driver.

Since each service, whether it's written in Ruby or Golang, uses the
same connection-string, it should be very easy to configure all
services in a cluster, or even a single development machine to be
setup to use tracing.

Note that this change does not include instrumentation or propagation
changes as this is a way of breaking a previous larger change into
components. The instrumentation and propagation changes will follow
in separate changes.

GitLab::Sentry has a program_context method to determine whether a
Sentry exception occurred in Sidekiq or rails. Since we will need
similar functionality for distributed tracing, this change extracts the
program_context method into GitLab.process_name for more general
consumption.

These are data columns that store runtime configuration
of build needed to execute it on runner and within pipeline.

The definition of this data is that once used, and when no longer
needed (due to retry capability) they can be freely removed.

They use `jsonb` on PostgreSQL, and `text` on MySQL (due to lacking
support for json datatype on old enough version).

Fix deprecation: returning false in Active Record and Active Model callbacks will not implicitly halt a callback chain

ActiveRecord supports `:order` natively, but it is skipped because of
our specific patch to support opclasses.

Relevant AR code:
https://github.com/rails/rails/blob/5-0-stable/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb#L1167

Full list of changes:
https://github.com/carrierwaveuploader/carrierwave/blob/master/CHANGELOG.md

Because this could potentially load a model and we shouldn't
load models before all the patches we have in places.

Metrics tries to initialize the `EventsFinder` to instrumnt it. The `EventsFinder` tries to load the `Event` model, which in turn loads the `User` model.

Loading the `User` model requires Devise to be initialized. So to avoid problems around this, we load devise before loading metrics.

Even in AWS S3 compatibility mode, Google now appears to reject requests
that includes this header with this error:

```
Requests cannot specify both x-amz and x-goog headers
```

This has been submitted upstream via
https://github.com/carrierwaveuploader/carrierwave/pull/2356.

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/53846.

The use of `table_exists?` in the opclasses support initializer triggers
a deprecation warning. Using `data_source_exists?` removes this
deprecation.

The Correlation ID is taken or generated from received X-Request-ID.
Then it is being passed to all executed services (sidekiq workers
or gitaly calls).

The Correlation ID is logged in all structured logs as `correlation_id`.

The GitLab Development Kit initialization failed because the Sidekiq
initializer was attempting to look up a feature flag when the `features`
table hadn't been created yet.

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/54718

Adds gitlab.impersonation_enabled config option defaulting to true to
keep the current default behaviour.

Only the act of impersonation is modified, impersonation token
management is not affected.

[master] Resolve: "Provide email notification when a user changes their email address"

See merge request gitlab/gitlabhq!2587

[master] Resolve "Reflected XSS in OAuth Authorize window due to redirect_uri allowing arbitrary protocols"

See merge request gitlab/gitlabhq!2572

[master] Resolve "Personal access token with only `read_user` scope can be used to authenticate any web request"

See merge request gitlab/gitlabhq!2583

If the EncryptColumns background migration runs in a sidekiq with a
stale view of the database schema, or when the purported destination
columns don't actually exist, data loss can result. Attempt to work
around these issues by reloading schema information before running
the migration, and raising errors if the model reports that any of its
source or destination columns are missing.

See
https://github.com/abonas/kubeclient/blob/v4.0.0/lib/kubeclient/common.rb#L395

* similar to rails 5 it assures that index length is set for blob
  columns also in rails 4
* it also ignores multiple definitions of indexes for mysql, for some
  tables we define multiple indexes on the same set of columns, but with
  different parameters (opclasses, where), these are not supported by
  mysql adapter so the second definition of index is skipped