Controller: Retain default backend service information.
What this PR does / why we need it:
This is a copy of accidentally closed PR !12160 (closed)
When the default backend is used as upstream, the information about its service is lost. As a consequence, if the default backend is an ExternalName service, it is used as a non-ExternalName service in the Lua part.
Types of changes
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Bug fix (non-breaking change which fixes an issue) -
New feature (non-breaking change which adds functionality) -
CVE Report (Scanner found CVE and adding report) -
Breaking change (fix or feature that would cause existing functionality to change) -
Documentation only
Which issue/s this PR fixes
fixes #12158 (closed) fixes #12173
How Has This Been Tested?
The test case is described in #12158 (closed).
Checklist:
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My change requires a change to the documentation. -
I have updated the documentation accordingly. -
I've read the CONTRIBUTION guide -
I have added unit and/or e2e tests to cover my changes. -
All new and existing tests passed.