314 lines
11 KiB
Plaintext
314 lines
11 KiB
Plaintext
gitcredentials(7)
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=================
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NAME
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----
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gitcredentials - Providing usernames and passwords to Git
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SYNOPSIS
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--------
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------------------
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git config credential.https://example.com.username myusername
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git config credential.helper "$helper $options"
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------------------
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DESCRIPTION
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-----------
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Git will sometimes need credentials from the user in order to perform
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operations; for example, it may need to ask for a username and password
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in order to access a remote repository over HTTP. Some remotes accept
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a personal access token or OAuth access token as a password. This
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manual describes the mechanisms Git uses to request these credentials,
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as well as some features to avoid inputting these credentials repeatedly.
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REQUESTING CREDENTIALS
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----------------------
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Without any credential helpers defined, Git will try the following
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strategies to ask the user for usernames and passwords:
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1. If the `GIT_ASKPASS` environment variable is set, the program
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specified by the variable is invoked. A suitable prompt is provided
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to the program on the command line, and the user's input is read
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from its standard output.
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2. Otherwise, if the `core.askPass` configuration variable is set, its
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value is used as above.
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3. Otherwise, if the `SSH_ASKPASS` environment variable is set, its
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value is used as above.
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4. Otherwise, the user is prompted on the terminal.
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AVOIDING REPETITION
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-------------------
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It can be cumbersome to input the same credentials over and over. Git
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provides two methods to reduce this annoyance:
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1. Static configuration of usernames for a given authentication context.
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2. Credential helpers to cache or store passwords, or to interact with
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a system password wallet or keychain.
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The first is simple and appropriate if you do not have secure storage available
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for a password. It is generally configured by adding this to your config:
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---------------------------------------
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[credential "https://example.com"]
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username = me
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---------------------------------------
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Credential helpers, on the other hand, are external programs from which Git can
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request both usernames and passwords; they typically interface with secure
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storage provided by the OS or other programs. Alternatively, a
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credential-generating helper might generate credentials for certain servers via
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some API.
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To use a helper, you must first select one to use. Git currently
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includes the following helpers:
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cache::
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Cache credentials in memory for a short period of time. See
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linkgit:git-credential-cache[1] for details.
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store::
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Store credentials indefinitely on disk. See
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linkgit:git-credential-store[1] for details.
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You may also have third-party helpers installed; search for
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`credential-*` in the output of `git help -a`, and consult the
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documentation of individual helpers. Once you have selected a helper,
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you can tell Git to use it by putting its name into the
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credential.helper variable.
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1. Find a helper.
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+
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-------------------------------------------
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$ git help -a | grep credential-
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credential-foo
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-------------------------------------------
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2. Read its description.
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+
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-------------------------------------------
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$ git help credential-foo
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-------------------------------------------
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3. Tell Git to use it.
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+
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-------------------------------------------
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$ git config --global credential.helper foo
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-------------------------------------------
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=== Available helpers
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The community maintains a comprehensive list of Git credential helpers at
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https://git-scm.com/doc/credential-helpers.
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=== OAuth
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An alternative to inputting passwords or personal access tokens is to use an
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OAuth credential helper. Initial authentication opens a browser window to the
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host. Subsequent authentication happens in the background. Many popular Git
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hosts support OAuth.
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CREDENTIAL CONTEXTS
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-------------------
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Git considers each credential to have a context defined by a URL. This context
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is used to look up context-specific configuration, and is passed to any
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helpers, which may use it as an index into secure storage.
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For instance, imagine we are accessing `https://example.com/foo.git`. When Git
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looks into a config file to see if a section matches this context, it will
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consider the two a match if the context is a more-specific subset of the
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pattern in the config file. For example, if you have this in your config file:
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--------------------------------------
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[credential "https://example.com"]
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username = foo
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--------------------------------------
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then we will match: both protocols are the same, both hosts are the same, and
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the "pattern" URL does not care about the path component at all. However, this
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context would not match:
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--------------------------------------
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[credential "https://kernel.org"]
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username = foo
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--------------------------------------
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because the hostnames differ. Nor would it match `foo.example.com`; Git
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compares hostnames exactly, without considering whether two hosts are part of
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the same domain. Likewise, a config entry for `http://example.com` would not
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match: Git compares the protocols exactly. However, you may use wildcards in
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the domain name and other pattern matching techniques as with the `http.<URL>.*`
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options.
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If the "pattern" URL does include a path component, then this too must match
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exactly: the context `https://example.com/bar/baz.git` will match a config
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entry for `https://example.com/bar/baz.git` (in addition to matching the config
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entry for `https://example.com`) but will not match a config entry for
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`https://example.com/bar`.
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CONFIGURATION OPTIONS
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---------------------
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Options for a credential context can be configured either in
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`credential.*` (which applies to all credentials), or
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`credential.<URL>.*`, where <URL> matches the context as described
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above.
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The following options are available in either location:
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helper::
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The name of an external credential helper, and any associated options.
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If the helper name is not an absolute path, then the string `git
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credential-` is prepended. The resulting string is executed by the
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shell (so, for example, setting this to `foo --option=bar` will execute
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`git credential-foo --option=bar` via the shell. See the manual of
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specific helpers for examples of their use.
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+
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If there are multiple instances of the `credential.helper` configuration
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variable, each helper will be tried in turn, and may provide a username,
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password, or nothing. Once Git has acquired both a username and a
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non-expired password, no more helpers will be tried.
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+
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If `credential.helper` is configured to the empty string, this resets
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the helper list to empty (so you may override a helper set by a
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lower-priority config file by configuring the empty-string helper,
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followed by whatever set of helpers you would like).
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username::
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A default username, if one is not provided in the URL.
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useHttpPath::
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By default, Git does not consider the "path" component of an http URL
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to be worth matching via external helpers. This means that a credential
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stored for `https://example.com/foo.git` will also be used for
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`https://example.com/bar.git`. If you do want to distinguish these
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cases, set this option to `true`.
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CUSTOM HELPERS
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--------------
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You can write your own custom helpers to interface with any system in
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which you keep credentials.
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Credential helpers are programs executed by Git to fetch or save
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credentials from and to long-term storage (where "long-term" is simply
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longer than a single Git process; e.g., credentials may be stored
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in-memory for a few minutes, or indefinitely on disk).
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Each helper is specified by a single string in the configuration
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variable `credential.helper` (and others, see linkgit:git-config[1]).
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The string is transformed by Git into a command to be executed using
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these rules:
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1. If the helper string begins with "!", it is considered a shell
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snippet, and everything after the "!" becomes the command.
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2. Otherwise, if the helper string begins with an absolute path, the
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verbatim helper string becomes the command.
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3. Otherwise, the string "git credential-" is prepended to the helper
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string, and the result becomes the command.
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The resulting command then has an "operation" argument appended to it
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(see below for details), and the result is executed by the shell.
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Here are some example specifications:
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----------------------------------------------------
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# run "git credential-foo"
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[credential]
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helper = foo
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# same as above, but pass an argument to the helper
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[credential]
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helper = "foo --bar=baz"
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# the arguments are parsed by the shell, so use shell
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# quoting if necessary
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[credential]
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helper = "foo --bar='whitespace arg'"
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# you can also use an absolute path, which will not use the git wrapper
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[credential]
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helper = "/path/to/my/helper --with-arguments"
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# or you can specify your own shell snippet
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[credential "https://example.com"]
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username = your_user
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helper = "!f() { test \"$1\" = get && echo \"password=$(cat $HOME/.secret)\"; }; f"
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----------------------------------------------------
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Generally speaking, rule (3) above is the simplest for users to specify.
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Authors of credential helpers should make an effort to assist their
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users by naming their program "git-credential-$NAME", and putting it in
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the `$PATH` or `$GIT_EXEC_PATH` during installation, which will allow a
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user to enable it with `git config credential.helper $NAME`.
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When a helper is executed, it will have one "operation" argument
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appended to its command line, which is one of:
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`get`::
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Return a matching credential, if any exists.
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`store`::
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Store the credential, if applicable to the helper.
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`erase`::
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Remove matching credentials, if any, from the helper's storage.
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The details of the credential will be provided on the helper's stdin
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stream. The exact format is the same as the input/output format of the
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`git credential` plumbing command (see the section `INPUT/OUTPUT
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FORMAT` in linkgit:git-credential[1] for a detailed specification).
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For a `get` operation, the helper should produce a list of attributes on
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stdout in the same format (see linkgit:git-credential[1] for common
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attributes). A helper is free to produce a subset, or even no values at
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all if it has nothing useful to provide. Any provided attributes will
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overwrite those already known about by Git's credential subsystem.
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Unrecognised attributes are silently discarded.
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While it is possible to override all attributes, well behaving helpers
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should refrain from doing so for any attribute other than username and
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password.
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If a helper outputs a `quit` attribute with a value of `true` or `1`,
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no further helpers will be consulted, nor will the user be prompted
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(if no credential has been provided, the operation will then fail).
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Similarly, no more helpers will be consulted once both username and
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password had been provided.
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For a `store` or `erase` operation, the helper's output is ignored.
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If a helper fails to perform the requested operation or needs to notify
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the user of a potential issue, it may write to stderr.
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If it does not support the requested operation (e.g., a read-only store
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or generator), it should silently ignore the request.
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If a helper receives any other operation, it should silently ignore the
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request. This leaves room for future operations to be added (older
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helpers will just ignore the new requests).
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GIT
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---
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Part of the linkgit:git[1] suite
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