[VS Code] Read gitlab token from a file to configure the extension

MR: feat: read PAT from file (!1622 - merged)

Context

We are looking to integrate GitLab Workflow extension out of the box when creating a workspace as part of Integrate Duo Chat and Code Suggestions into a ... (&12780 - closed) . When a workspace is created, a new PAT is generated. We plan to add api scope into this token so that it can be used directly to configure the extension. However, this token is stored in a file in a workspace and not as an environment variable. There are reasons why we prefer to have the token in a file over an environment variable.

Solution

Support reading a token from a file instead of reading the token from an environment variable.

We introduce a new environment variable called GITLAB_WORKFLOW_TOKEN_FILE. This environment variable contains the path to a file whose only content is the token text in UTF-8.

Current use of env variables:

GITLAB_WORKFLOW_INSTANCE_URL=https://gitlab.com GITLAB_WORKFLOW_TOKEN="glab-actual-token" code .

Newly supported option:

GITLAB_WORKFLOW_INSTANCE_URL=https://gitlab.com GITLAB_WORKFLOW_TOKEN_FILE=~/.shared-gitlab-token code .

and the ~/.shared-gitlab-token file would be this:

glab-actual-token-on-line-1

If both GITLAB_WORKFLOW_TOKEN and GITLAB_WORKFLOW_TOKEN_FILE env variables are present, GITLAB_WORKFLOW_TOKEN has priority (GITLAB_WORKFLOW_TOKEN_FILE will be ignored).

Technical details

• We now read the authentication environment variables here https://gitlab.com/gitlab-org/gitlab-vscode-extension/blob/7f4a3eb0168693c9671c595bf9725e4ec66eeca3/src/desktop/accounts/account_service.ts#L49-58
• Since reading environment variables is sync operation and reading file is async, we need to find a good spot when to read the file. Maybe we could use the init method that is called when the account service is created https://gitlab.com/gitlab-org/gitlab-vscode-extension/blob/7f4a3eb0168693c9671c595bf9725e4ec66eeca3/src/desktop/accounts/account_service.ts#L88-98.
• the precedence should take environment variables (GITLAB_WORKFLOW_INSTANCE_URL, GITLAB_WORKFLOW_TOKEN) first to prevent breaking the existing setup
• if the loading credentials from GITLAB_WORKFLOW_CREDENTIALS_FILE fails, we log the error but otherwise ignore it
• the new logic should be tested