Catalog API: Could not read location from Gitlab repo ($text placeholder)

Expected Behaviour

In my org we have OpenAPI definitions (swagger.yaml), hosted in a private GitLab repository, accessible only by authenticated users.

API definitions are using raw GitLab URLs, with $text placeholder:

apiVersion: backstage.io/v1alpha1
kind: API
metadata:
  name: service-name
  description:  |
    Service Description
spec:
  type: openapi
  owner: project-owner
  lifecycle: production
  system: production
  definition:
    $text: https://gitlab.host.tld/org/group-name/subgroup-name/service-name/raw/master/swagger.yaml

GitLab discovery is enabled and correctly working for catalog-info.yaml files ingestion.

I would then expect also swagger.yaml files to be correctly read from the given definitions.

Actual Behaviour

Unfortunately, an error is occurring while creating the API catalog entities. It seems $text placeholder doesn’t work with the above provided raw URLs.

Steps to Reproduce

1. Provide a swagger.yml file on a private repos (self-hosted GitLab installation).
2. Create an API resource on catalog-info.yaml using $text placeholder.
3. Register the component by using backstage UI.

Context

{"error":{"name":"Error","message":"InputError: Processor PlaceholderProcessor threw an error while preprocessing; caused by Error: Placeholder $text could not read location https://gitlab.host.tld/org/group-name/subgroup-name/service-name/raw/master/swagger.yaml, Error: Incorrect url: https://gitlab.host.tld/org/group-name/subgroup-name/service-name/raw/master/swagger.yaml, Error: Wrong GitLab URL","level":"error","service":"backstage"},"request":{"method":"POST","url":"/locations?dryRun=true"},"response":{"statusCode":500}}

An attempt has also been made by using regular “blob” urls.

Your Environment

Gitlab discovery is correctly configured and working for catalog entities creation.

Adding the gitlab instance hostname to backend.reading.allow config setting (as documented here https://backstage.io/docs/features/software-catalog/descriptor-format#kind-api) didn’t work as expected.

OS:   Darwin 21.2.0 - darwin/x64
node: v16.4.0
yarn: 1.22.15
cli:  0.11.0 (installed)

Dependencies:
  @backstage/app-defaults                                  0.1.4
  @backstage/backend-common                                0.10.3
  @backstage/backend-tasks                                 0.1.3
  @backstage/catalog-client                                0.5.4
  @backstage/catalog-model                                 0.9.9
  @backstage/cli-common                                    0.1.6
  @backstage/cli                                           0.11.0
  @backstage/config-loader                                 0.9.2
  @backstage/config                                        0.1.12
  @backstage/core-app-api                                  0.4.0
  @backstage/core-components                               0.8.4
  @backstage/core-plugin-api                               0.5.0
  @backstage/dev-utils                                     0.2.17
  @backstage/errors                                        0.2.0
  @backstage/integration-react                             0.1.18
  @backstage/integration                                   0.7.1
  @backstage/plugin-api-docs                               0.6.22
  @backstage/plugin-app-backend                            0.3.21
  @backstage/plugin-auth-backend                           0.6.2
  @backstage/plugin-catalog-backend                        0.20.0
  @backstage/plugin-catalog-common                         0.1.0
  @backstage/plugin-catalog-import                         0.7.9
  @backstage/plugin-catalog-react                          0.6.11
  @backstage/plugin-catalog                                0.7.8
  @backstage/plugin-github-actions                         0.4.31
  @backstage/plugin-org                                    0.3.34
  @backstage/plugin-permission-common                      0.3.1
  @backstage/plugin-permission-node                        0.3.0
  @backstage/plugin-permission-react                       0.2.2
  @backstage/plugin-proxy-backend                          0.2.15
  @backstage/plugin-scaffolder-backend-module-cookiecutter 0.1.8
  @backstage/plugin-scaffolder-backend                     0.15.20
  @backstage/plugin-scaffolder-common                      0.1.2
  @backstage/plugin-scaffolder                             0.11.18
  @backstage/plugin-search-backend-node                    0.4.4
  @backstage/plugin-search-backend                         0.3.0
  @backstage/plugin-search                                 0.5.5
  @backstage/plugin-sentry                                 0.3.33
  @backstage/plugin-tech-radar                             0.5.2
  @backstage/plugin-techdocs-backend                       0.12.3
  @backstage/plugin-techdocs                               0.12.14
  @backstage/plugin-user-settings                          0.3.16
  @backstage/search-common                                 0.2.1
  @backstage/techdocs-common                               0.11.3
  @backstage/test-utils                                    0.2.2
  @backstage/theme                                         0.2.14
  @backstage/types                                         0.1.1
  @backstage/version-bridge                                0.1.1
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