Implement new PAT API endpoint 'id'

What does this MR do and why?

Fixes #362239 (closed)

Adds a new endpoint to personal access token (PAT) API to get a single PAT by its id.

The api route is /personal_access_tokens/:id

🛠 with ❤ at Siemens

Examples

Admin PAT = y4m_EVDK2Mbg-RDSBZgN
User PAT = kG9Biwc4393jdhfekr7o

When accessing the own PAT

curl --header "PRIVATE-TOKEN: kG9Biwc4393jdhfekr7o" "https://gitlab.example.com/api/v4/personal_access_tokens/6

[
    {
        "id": 6,
        "name": "Test Token",
        "revoked": false,
        "created_at": "2022-01-01T14:31:47.729Z",
        "scopes": [
            "api"
        ],
        "user_id": 40,
        "last_used_at": "2022-05-18T17:58:37.550Z",
        "active": true,
        "expires_at": null
    }
]

When trying to access a foreign PAT as non-administrator

curl --header "PRIVATE-TOKEN: kG9Biwc4393jdhfekr7o" "https://gitlab.example.com/api/v4/personal_access_tokens/1

{ "message": "401 Unauthorized" }

When trying to access a foreign PAT as administrator

curl --header "PRIVATE-TOKEN: y4m_EVDK2Mbg-RDSBZgN" "https://gitlab.example.com/api/v4/personal_access_tokens/6

[
    {
        "id": 6,
        "name": "Test Token",
        "revoked": false,
        "created_at": "2022-01-01T14:31:47.729Z",
        "scopes": [
            "api"
        ],
        "user_id": 40,
        "last_used_at": "2022-05-18T17:58:37.550Z",
        "active": true,
        "expires_at": null
    }
]

When trying to access a PAT which does not exist either as administrator or non-administrator

curl --header "PRIVATE-TOKEN: y4m_EVDK2Mbg-RDSBZgN" "https://gitlab.example.com/api/v4/personal_access_tokens/1000

{ "message": "401 Unauthorized" }

How to set up and validate locally

1. Create a PAT token
2. Run the following command

curl --request GET --header "PRIVATE-TOKEN: <your_access_token>" https://gitlab.example.com/api/v4/personal_access_tokens/<id>

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.