gitcreds_get: Query and set git credentials

In gitcreds: Query 'git' Credentials from 'R'

Query and set git credentials

Description

This manual page is for users of packages that depend on gitcreds for managing tokens or passwords to GitHub or other git repositories. If you are a package author and want to import gitcreds for this functionality, see vignette("package", package = "gitcreds"). Otherwise please start at 'Basics' below.

Usage

gitcreds_get(url = "https://github.com", use_cache = TRUE, set_cache = TRUE)

gitcreds_set(url = "https://github.com")

gitcreds_delete(url = "https://github.com")

gitcreds_list_helpers()

Arguments

url	URL to get, set or delete credentials for. It may contain a user name, which is typically (but not always) used by the credential helpers. It may also contain a path, which is typically (but not always) ignored by the credential helpers.
use_cache	Whether to try to use the environment variable cache before turning to git to look up the credentials for url. See gitcreds_cache_envvar().
set_cache	Whether to set the environment variable cache after receiving the credentials from git. See gitcreds_cache_envvar().

Value

gitcreds_get() returns a gitcreds object, a named list of strings, the fields returned by the git credential handler. Typically the fields are protocol, host, username, password. Some credential helpers support path-dependent credentials and also return a path field.

gitcreds_set() returns nothing.

gitcreds_delete() returns FALSE if it did not find find any credentials to delete, and thus it did not call git credential reject. Otherwise it returns TRUE.

gitcreds_get() errors if git is not installed, no credential helpers are configured or no credentials are found. gitcreds_set() errors if git is not installed, or setting the new credentials fails. gitcreds_delete() errors if git is not installed or the git calls fail. See vignette("package", package = "gitcreds") if you want to handle these errors.

gitcreds_list_helpers() returns a character vector, corresponding to the credential.helper git configuration key. Usually it contains a single credential helper, but it is possible to configure multiple helpers.

Basics

gitcreds_get() queries git credentials. It is typically used by package code that needs to authenticate to GitHub or another git repository. The end user might call gitcreds_get() directly to check that the credentials are properly set up.

gitcreds_set() adds or updates git credentials in the credential store. It is typically called by the user, and it only works in interactive sessions. It always asks for acknowledgement before it overwrites existing credentials.

gitcreds_delete() deletes git credentials from the credential store. It is typically called by the user, and it only works in interactive sessions. It always asks for acknowledgement.

gitcreds_list_helpers() lists the active credential helpers.

git versions

These functions use the git credential system command to query and set git credentials. They need an external git installation. You can download git from https://git-scm.com/downloads. A recent version is best, but at least git 2.9 is suggested.

gitcreds should work out of the box on macOS with git versions 2.9.2 or later, and on Windows with git versions 2.12.1 or later, using the default git settings. On Windows, for git versions from 2.9.2 up until 2.12.1 you probably need to set the default credential helper to wincred. It is usually simpler to update git to a recent version.

To see your current git version run git --version from your shell. Or from R:

system("git --version")

If you need to avoid installing git, see 'Environment variables' below.

GitHub

New setup

To set up password-less authentication to GitHub:

1. Create a personal access token (PAT). See https://docs.github.com/en/github/authenticating-to-github/creating-a-personal-access-token.

2. Call gitcreds_set() and give this token as the password.

3. Run gitcreds_get(use_cache = FALSE) to check that the new PAT is set up. To see the token, you can run gitcreds_get(use_cache = FALSE)$password.

Migrating from the GITHUB_PAT environment variable

If you already have a GitHub token, and use the GITHUB_PAT or GITHUB_TOKEN environment variable in your .Renviron file or elsewhere, no changes are neccessary. gitcreds will automatically use this variable.

However, we still suggest that you add your token to the git credential store with gitcreds_set() and remove GITHUB_PAT from your .Renviron file. The credential store is more secure than storing tokens in files, and command line git also uses the credential store for password-less authentication.

Advanced topics

Cached credentials

Because querying the git credential store might not be very fast, gitcreds_get() caches credentials in environment variables by default. Credentials for different URLs are stored in different environment variables. The name of the environment variable is calculated with gitcreds_cache_envvar().

To remove the cache, remove this environment variable with Sys.unsetenv().

Environment variables

If you want to avoid installing git, or using the credential store for some reason, you can supply credentials in environment variables, e.g. via the .Renviron file. Use gitcreds_cache_envvar() to query the environment variable you need to set for a URL:

1. You can set this environment variable to the token or password itself.

2. If you also need a user name, then use the user:password form, i.e. separate them with a colon. (If your user name or passwrd has : characters, then you need to escape them with a preceding backslash.)

Proxies

git should pick up the proxy configuration from the http_proxy, https_proxy, and all_proxy environment variables. To override these, you can set the http.proxy git configuration key. More info here: https://git-scm.com/docs/git-config#Documentation/git-config.txt-httpproxy and here: https://github.com/microsoft/Git-Credential-Manager-Core/blob/master/docs/netconfig.md

Credential helpers

git credential helpers are an extensible, configurable mechanism to store credentials. Different git installations have different credentials helpers. On Windows the default helper stores credentials in the system credential store. On macOS, it stores them in the macOS Keychain. Other helpers cache credentials in a server process or in a file on the file system.

gitcreds only works if a credential helper is configured. For the current git version (2.29.0), this is the case by default on Windows and macOS (for git from HomeBrew), but most Linux distributions do not set up a default credential helper.

You can use gitcreds_list_helpers() to see the active credential helper(s) for a repository. Make sure you set the working directory to the git tree before calling gitcreds_list_helpers().

The current working directory

git allows repository specific configuration, via the .git/config file. The config file might specify a different credential helper, a different user name, etc. This means that gitcreds_get() etc. will potentially work differently depending on the current working directory. This is especially relevant for package code that changes the working directory temporarily.

Non-GitHub accounts

Non-GitHub URLs work mostly the same way as GitHub URLs. gitcreds_get() and gitcreds_set() default to GitHub, so you'll need to explicitly set their url argument.

Some credential helpers, e.g. Git Credential Manager for Windows (manager) and Git Credential Manager Core (manager-core) work slightly differently for GitHub and non-GitHub URLs, see their documentation for details.

Multiple accounts

The various credential helpers support having multiple accounts on the same server in different ways. Here are our recommendations.

macOS

1. Use the (currently default) osxkeychain credential helper.

2. In Keychain Access, remove all your current credentials for the host(s) you are targeting. E.g. for GitHub, search for github.com Internet Passwords.

3. Then add the credential that you want to use for "generic access". This is the credential that will be used for URLs without user names. The user name for this credential does not matter, but you can choose something descriptive, e.g. "token", or "generic".

4. Configure git to use this username by default. E.g. if you chose "generic", then run

   git config --global credential.username generic
   

5. Add all the other credentials, with appropriate user names. These are the user names that you need to put in the URLs for the repositories or operations you want to use them for. (GitHub does not actually use the user names if the password is a PAT, but they are used to look up the correct token in the credential store.)

Windows with git 2.29.0 or later

1. We suggest that you update to the latest git version, but at least 2.29.0, and use the manager-core helper which is now default. If you installed manager-core separately from git, we suggest that you remove it, because it might cause confusion as to which helper is actually used.

2. Remove all current credentials first, for the host you are targeting. You can do this in 'Credential Manager' or gitcreds::gitcreds_list() to find them and 'Credential Manager' or the oskeyring package to remove them. You can also use the oskeyring package to back up the tokens and passwords.

3. Then add the credential that you want to use for "generic access". This is the credential that will be used for URLs without user names. The user name for this credential does not matter, but you can choose something descriptive, e.g. "PersonalAccessToken", "token", or "generic".

4. Configure git to use this username by default. E.g. if you chose "generic", then run

   git config --global credential.username generic
   

5. Add all the other credentials, with appropriate user names. These are the user names that you need to put in the URLs for the repositories or operations you want to use them for. (GitHub does not actually use the user names if the password is a PAT, but they are used to look up the correct token from the credential store.)

Windows with older git versions, 2.28.0 and before

A single GitHub account

If you only need to manage a single github.com credential, together with possibly multiple credentials to other hosts (including GitHub Enterprise hosts), then you can use the default manager helper, and get away with the default auto-detected GCM authority setting.

In this case, you can add your github.com credential with an arbitrary user name, and for each other host you can configure a default user name, and/or include user names in the URLs to these hosts. This is how to set a default user name for a host called https://example.com:

git config --global credential.https://example.com.username myusername

Multiple GitHub credentials

If you need to manage multiple github.com credentials, then you can still use the manager helper, but you need to change the GCM authority by setting an option or an environment variable, see https://github.com/microsoft/Git-Credential-Manager-for-Windows/blob/master/Docs/Configuration.md#authority.

This is how to change GCM authority in the config:

git config --global credential.authority Basic

You can also change it only for github.com:

git config --global credential.github.com.authority Basic

Then you can configure a default user name, this will be used for URLs without a user name:

git config --global credential.username generic

Now you can add you credentials, the default one with the "generic" user name, and all the others with their specific user and host names.

Alternatively, you can install a newer version of Git Credential Manager Core (GCM Core), at least version 2.0.252-beta, and use the manager-core helper. You'll potentially need to delete the older manager-core helper that came with git itself. With the newer version of GCM Core, you can use the same method as for newer git versions, see above.

Multiple credential helpers

It is possible to configure multiple credential helpers. If multiple helpers are configured for a repository, then gitcreds_get() will go over them until a credential is found. gitcreds_set() will try to set the new credentials in every configured credential helper.

You can use gitcreds_list_helpers() to list all configured helpers.

Examples

## Not run: 
gitcreds_get()
gitcreds_get("https://github.com")
gitcreds_get("https://[e-mail]/myorg/myrepo")

## End(Not run)

gitcreds documentation built on Sept. 8, 2022, 5:08 p.m.