Add backward compatibility for Conan v1 with revision '0'

Context

In Add backward compatibility for Conan v1 with re... (!218278 - merged) we already tried to add a backward compatibility for Conan v1. However, it led to issue with Conan v2 Conan 2 Error: object of type NoneType has no l... (#587177 - closed). And the changes were reverted in Revert "Merge branch '561028-conan-server-side-... (!222323 - merged).

After the investigation it was revealed that the response with default revision needs to have time field with value.

What does this MR do and why?

Add backward compatibility for Conan v1 with revision '0'

Support Conan v1 clients that use the default revision '0' when recipe revisions are disabled. This ensures the v2 API endpoints can serve packages uploaded via Conan v1.

Changes in details

• Modify /v2/conans/:package_name/:package_version/:username/:channel/latest to return default recipe revision "0" when no revisions exist. Example of response:

  {
    "revision": "0",
    "time": "2026-02-25T09:28:03.044Z"
  }

  The default recipe revision "0" will be used for subsequent API requests:

• Modify /v2/conans/:package_name/:package_version/:username/:channel/revisions/:recipe_revision/packages/:package_reference/latest to return default package revision "0" when no revisions exist. Example of response:

  {
    "revision": "0",
    "time": "2026-02-25T09:28:03.044Z"
  }

• Modify /v2/conans/:package_name/:package_version/:username/:channel/revisions/:recipe_revision/search to return references without revisions.
• Change the revision regexp to accept default revision "0".

References

Conan server side Rest API is no longer compati... (#561028)

Screenshots or screen recordings

No.

How to set up and validate locally

Prerequisites

Enabled the feature flag Feature.enable(:packages_conan_v1_revisions_backward_compatibility)

Conan v1

1. Install Conan v1 client

   $ brew install conan@1

2. Make sure that revisions are disabled in the config file

   $ vim ~/.conan/conan.conf
   
   [general]
   revisions_enabled = 0

3. Setup GitLab package registry https://docs.gitlab.com/user/packages/conan_1_repository/

   $ conan remote add local http://gdk.test:3000/api/v4/projects/<PROJECT_ID>/packages/conan False
   $ conan user <username> -r local -p <glpat>

4. Create and upload a test package

   $ mkdir strawberry && cd strawberry
   $ conan new strawberry/1.0.0 --template=cmake_lib
   $ conan create .
   $ conan upload strawberry/1.0.0 -r local --all

   Verify that the package was uploaded.

5. Clean cache

   $ rm -rf ~/.conan/data/strawberry

6. Make sure that revisions are enabled in the config file

   $ vim ~/.conan/conan.conf
   
   [general]
   revisions_enabled = 1

7. Prepare install

   $ cd ../ # go one level back
   $ vim conanfile.txt # create conanfile.txt with the following content:
   [requires]
   strawberry/1.0.0

8. Install package

   $ conan install . -r local

   The package will be installed using the v2 endpoints.

Conan v2

1. Install Conan v2 client

   $ brew install conan@2

2. Setup GitLab package registry

   $ conan remote add local http://gdk.test:3000/api/v4/projects/<PROJECT_ID>/packages/conan
   $ conan remote login local
   # Enter username and password (glpat)

3. Create and upload a test package

   $ mkdir test && cd test
   $ conan new basic -d name=test -d version=1.0.0
   $ conan create .
   $ conan upload test/1.0.0 -r local

   Verify that the package was uploaded.

4. Clean cache

   $ rm -rf ~/.conan2/p

5. Prepare install

   $ cd ../ # go one level back
   $ vim conanfile.txt # create conanfile.txt with the following content:
   [requires]
   test/1.0.0

6. Install package

   $ conan install . -r local

   The package should be successfully installed

MR acceptance checklist

Evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Related to #561028