Add ability to use GH CLI Authentication (#66)

Author: choldgraf

docs/index.md

@@ -80,11 +80,36 @@ You can choose to *remove* some types of PRs from your changelog by passing the
 left-most column above.
 ```
 
-### Using a GitHub API token
+## Use a GitHub API token
 
 `github-activity` uses the GitHub API to pull information about a repository's activity.
-You will quickly hit your API limit unless you use a personal access token. Here are
-instructions to generate and use a GitHub access token for use with `github-activity`.
+You will quickly hit your API limit unless you use a personal access token.
+There are two ways that you can generate your own access token for use with `github-activity`, each is described below:
+
+### Create a token using the GitHub CLI
+
+You can use [the GitHub command line interface](https://cli.github.com/manual/) to authenticate your account and store an access token in your local environment.
+To do so, download the GitHub CLI, and run the following command:
+
+```bash
+# Authenticate with GitHub via the web interface
+gh auth login --web
+```
+
+This will open a web interface for you to authenticate.
+When finished, it will store an access token locally, which you can print with:
+
+```bash
+# Print an access token if it is stored
+gh auth status -t
+```
+
+This token will automatically be used by `github-activity` if it exists.
+
+### Manually create your own API token
+
+Alternativelly, you can create your own GitHub access token and store it yourself.
+To do so, follow these steps:
 
 - Create your own access token. Go to the [new GitHub access token page](https://github.com/settings/tokens/new)
   and follow the instructions. Note that while working with a public repository,
@@ -101,7 +126,7 @@ instructions to generate and use a GitHub access token for use with `github-acti
   for an environment variable called `GITHUB_ACCESS_TOKEN`. If it finds this variable,
   it will use this in the API calls to GitHub.
 
-## How does this tool define contributions in the reports?
+## How we define contributors in the reports
 
 GitHub Activity tries to automatically determine the unique list of contributors within
 a given window of time. There are many ways to define this, and there isn't necessarily a

github_activity/cli.py

@@ -53,7 +53,8 @@
     default=None,
     help=(
         "An authentication token for GitHub. If None, then the environment "
-        "variable `GITHUB_ACCESS_TOKEN` will be tried."
+        "variable `GITHUB_ACCESS_TOKEN` will be tried. If it does not exist "
+        "then attempt to infer the token from `gh auth status -t`."
     ),
 )
 parser.add_argument(

github_activity/github_activity.py

@@ -85,7 +85,8 @@ def get_activity(
         Return only issues or PRs. If None, both will be returned.
     auth : string | None
         An authentication token for GitHub. If None, then the environment
-        variable `GITHUB_ACCESS_TOKEN` will be tried.
+        variable `GITHUB_ACCESS_TOKEN` will be tried. If it does not exist,
+        then attempt to infer a token from `gh auth status -t`.
     cache : bool | str | None
         Whether to cache the returned results. If None, no caching is
         performed. If True, the cache is located at
@@ -108,16 +109,26 @@ def get_activity(
         # We have just org
         search_query = f"user:{org}"
 
-    auth = auth or os.environ.get("GITHUB_ACCESS_TOKEN")
     if not auth:
-        raise ValueError(
-            "Either the environment variable GITHUB_ACCESS_TOKEN or the "
-            "--auth flag or must be used to pass a Personal Access Token "
-            "needed by the GitHub API. You can generate a token at "
-            "https://github.com/settings/tokens/new. Note that while "
-            "working with a public repository, you don’t need to set any "
-            "scopes on the token you create."
-        )
+        if "GITHUB_ACCESS_TOKEN" in os.environ:
+            print("Using GH access token stored in `GITHUB_ACCESS_TOKEN`.")
+            auth = os.environ.get("GITHUB_ACCESS_TOKEN")
+        else:
+            out = run(shlex.split("gh auth status -t"), capture_output=True)
+            lines = [ii for ii in out.stderr.decode().split("\n") if "Token:" in ii]
+            if lines:
+                print("Using GH access token stored via GH CLI.")
+                auth = lines[0].split(": ")[-1].strip()
+            else:
+                raise ValueError(
+                    "Either the environment variable GITHUB_ACCESS_TOKEN or the "
+                    "--auth flag or must be used to pass a Personal Access Token "
+                    "needed by the GitHub API. You can generate a token at "
+                    "https://github.com/settings/tokens/new. Note that while "
+                    "working with a public repository, you don’t need to set any "
+                    "scopes on the token you create. Alternatively, you may log-in "
+                    "via the GitHub CLI (`gh auth login`)."
+                )
 
     # Figure out dates for our query
     since_dt, since_is_git_ref = _get_datetime_and_type(org, repo, since, auth)