get_managed_token {AzureAuth}

Manage Azure Active Directory OAuth 2.0 tokens

Description

Use these functions to authenticate with Azure Active Directory (AAD).

Usage

get_managed_token(resource, token_args = list(), use_cache = NULL)

get_azure_token(
  resource,
  tenant,
  app,
  password = NULL,
  username = NULL,
  certificate = NULL,
  auth_type = NULL,
  aad_host = "https://login.microsoftonline.com/",
  version = 1,
  authorize_args = list(),
  token_args = list(),
  use_cache = NULL,
  on_behalf_of = NULL,
  auth_code = NULL,
  device_creds = NULL
)

delete_azure_token(
  resource,
  tenant,
  app,
  password = NULL,
  username = NULL,
  certificate = NULL,
  auth_type = NULL,
  aad_host = "https://login.microsoftonline.com/",
  version = 1,
  authorize_args = list(),
  token_args = list(),
  on_behalf_of = NULL,
  hash = NULL,
  confirm = TRUE
)

load_azure_token(hash)

clean_token_directory(confirm = TRUE)

list_azure_tokens()

token_hash(
  resource,
  tenant,
  app,
  password = NULL,
  username = NULL,
  certificate = NULL,
  auth_type = NULL,
  aad_host = "https://login.microsoftonline.com/",
  version = 1,
  authorize_args = list(),
  token_args = list(),
  on_behalf_of = NULL
)

is_azure_token(object)

is_azure_v1_token(object)

is_azure_v2_token(object)

Arguments

resource

For AAD v1.0, the URL of your resource host, or a GUID. For AAD v2.0, a character vector of scopes, each consisting of a URL or GUID along with a path designating the access scope. See 'Details' below.

token_args

An optional list of further parameters for the token endpoint. These will be included in the body of the request for get_azure_token, or as URI query parameters for get_managed_token.

use_cache

If TRUE and cached credentials exist, use them instead of obtaining a new token. The default value of NULL means to use the cache only if AzureAuth is not running inside a Shiny app.

tenant

Your tenant. This can be a name ("myaadtenant"), a fully qualified domain name ("myaadtenant.onmicrosoft.com" or "mycompanyname.com"), or a GUID. It can also be one of the generic tenants "common", "organizations" or "consumers"; see 'Generic tenants' below.

app

The client/app ID to use to authenticate with.

password

For most authentication flows, this is the password for the app where needed, also known as the client secret. For the resource owner grant, this is your personal account password. See 'Details' below.

username

Your AAD username, if using the resource owner grant. See 'Details' below.

certificate

A file containing the certificate for authenticating with (including the private key), an Azure Key Vault certificate object, or a call to the cert_assertion function to build a client assertion with a certificate. See 'Certificate authentication' below.

auth_type

The authentication type. See 'Details' below.

aad_host

URL for your AAD host. For the public Azure cloud, this is ⁠https://login.microsoftonline.com/⁠. Change this if you are using a government or private cloud. Can also be a full URL, eg ⁠https://mydomain.b2clogin.com/mydomain/other/path/names/oauth2⁠ (this is relevant mainly for Azure B2C logins).

version

The AAD version, either 1 or 2. Authenticating with a personal account as opposed to a work or school account requires AAD 2.0. The default is AAD 1.0 for compatibility reasons, but you should use AAD 2.0 if possible.

authorize_args

An optional list of further parameters for the AAD authorization endpoint. These will be included in the request URI as query parameters. Only used if auth_type="authorization_code".

on_behalf_of

For the on-behalf-of authentication type, a token. This should be either an AzureToken object, or a string containing the JWT-encoded token itself.

auth_code

For the authorization_code flow, the code. Only used if auth_type == "authorization_code".

device_creds

For the device_code flow, the device credentials used to verify the session between the client and the server. Only used if auth_type == "device_code".

hash

The MD5 hash of this token, computed from the above inputs. Used by load_azure_token and delete_azure_token to identify a cached token to load and delete, respectively.

confirm

For delete_azure_token, whether to prompt for confirmation before deleting a token.

object

For is_azure_token, is_azure_v1_token and is_azure_v2_token, an R object.

Details

get_azure_token does much the same thing as httr::oauth2.0_token(), but customised for Azure. It obtains an OAuth token, first by checking if a cached value exists on disk, and if not, acquiring it from the AAD server. load_azure_token loads a token given its hash, delete_azure_token deletes a cached token given either the credentials or the hash, and list_azure_tokens lists currently cached tokens.

get_managed_token is a specialised function to acquire tokens for a managed identity. This is an Azure service, such as a VM or container, that has been assigned its own identity and can be granted access permissions like a regular user. The advantage of managed identities over the other authentication methods (see below) is that you don't have to store a secret password, which improves security. Note that get_managed_token can only be used from within the managed identity itself.

By default get_managed_token retrieves a token using the system-assigned identity for the resource. To obtain a token with a user-assigned identity, pass either the client, object or Azure resource ID in the token_args argument. See the examples below.

The resource arg should be a single URL or GUID for AAD v1.0. For AAD v2.0, it should be a vector of scopes, where each scope consists of a URL or GUID along with a path that designates the type of access requested. If a v2.0 scope doesn't have a path, get_azure_token will append the ⁠/.default⁠ path with a warning. A special scope is offline_access, which requests a refresh token from AAD along with the access token: without this scope, you will have to reauthenticate if you want to refresh the token.

The auth_code and device_creds arguments are intended for use in embedded scenarios, eg when AzureAuth is loaded from within a Shiny web app. They enable the flow authorization step to be separated from the token acquisition step, which is necessary within an app; you can generally ignore these arguments when using AzureAuth interactively or as part of an R script. See the help for build_authorization_uri for examples on their use.

token_hash computes the MD5 hash of its arguments. This is used by AzureAuth to identify tokens for caching purposes. Note that tokens are only cached if you allowed AzureAuth to create a data directory at package startup.

One particular use of the authorize_args argument is to specify a different redirect URI to the default; see the examples below.

Authentication methods

1. Using the authorization_code method is a multi-step process. First, get_azure_token opens a login window in your browser, where you can enter your AAD credentials. In the background, it loads the httpuv package to listen on a local port. Once you have logged in, the AAD server redirects your browser to a local URL that contains an authorization code. get_azure_token retrieves this authorization code and sends it to the AAD access endpoint, which returns the OAuth token.

2. The device_code method is similar in concept to authorization_code, but is meant for situations where you are unable to browse the Internet – for example if you don't have a browser installed or your computer has input constraints. First, get_azure_token contacts the AAD devicecode endpoint, which responds with a login URL and an access code. You then visit the URL and enter the code, possibly using a different computer. Meanwhile, get_azure_token polls the AAD access endpoint for a token, which is provided once you have entered the code.

3. The client_credentials method is much simpler than the above methods, requiring only one step. get_azure_token contacts the access endpoint, passing it either the app secret or the certificate assertion (which you supply in the password or certificate argument respectively). Once the credentials are verified, the endpoint returns the token. This is the method typically used by service accounts.

4. The resource_owner method also requires only one step. In this method, get_azure_token passes your (personal) username and password to the AAD access endpoint, which validates your credentials and returns the token.

5. The on_behalf_of method is used to authenticate with an Azure resource by passing a token obtained beforehand. It is mostly used by intermediate apps to authenticate for users. In particular, you can use this method to obtain tokens for multiple resources, while only requiring the user to authenticate once: see the examples below.

If the authentication method is not specified, it is chosen based on the presence or absence of the other arguments, and whether httpuv is installed.

The httpuv package must be installed to use the authorization_code method, as this requires a web server to listen on the (local) redirect URI. See httr::oauth2.0_token for more information; note that Azure does not support the use_oob feature of the httr OAuth 2.0 token class.

Similarly, since the authorization_code method opens a browser to load the AAD authorization page, your machine must have an Internet browser installed that can be run from inside R. In particular, if you are using a Linux Data Science Virtual Machine in Azure, you may run into difficulties; use one of the other methods instead.

Certificate authentication

OAuth tokens can be authenticated via an SSL/TLS certificate, which is considered more secure than a client secret. To do this, use the certificate argument, which can contain any of the following:

• The name of a PEM or PFX file, containing both the private key and the public certificate.

• A certificate object from the AzureKeyVault package, representing a cert stored in the Key Vault service.

• A call to the cert_assertion() function to customise details of the requested token, eg the duration, expiry date, custom claims, etc. See the examples below.

Generic tenants

There are 3 generic values that can be used as tenants when authenticating:

Tenant	Description
common	Allows users with both personal Microsoft accounts and work/school accounts from Azure AD to sign into the application.
organizations	Allows only users with work/school accounts from Azure AD to sign into the application.
consumers	Allows only users with personal Microsoft accounts (MSA) to sign into the application.

Authentication vs authorization

Azure Active Directory can be used for two purposes: authentication (verifying that a user is who they claim they are) and authorization (granting a user permission to access a resource). In AAD, a successful authorization process concludes with the granting of an OAuth 2.0 access token, as discussed above. Authentication uses the same process but concludes by granting an ID token, as defined in the OpenID Connect protocol.

get_azure_token can be used to obtain ID tokens along with regular OAuth access tokens, when using an interactive flow (authorization_code or device_code). The behaviour depends on the AAD version:

When retrieving ID tokens, the behaviour depends on the AAD version:

• AAD v1.0 will return an ID token as well as the access token by default; you don't have to do anything extra. However, AAD v1.0 will not refresh the ID token when it expires; you must reauthenticate to get a new one. To ensure you don't pull the cached version of the credentials, specify use_cache=FALSE in the calls to get_azure_token.

• Unlike AAD v1.0, AAD v2.0 does not return an ID token by default. To get a token, include openid as a scope. On the other hand it does refresh the ID token, so bypassing the cache is not needed. It's recommended to use AAD v2.0 if you only want an ID token.

If you only want to do authentication and not authorization (for example if your app does not use any Azure resources), specify the resource argument as follows:

• For AAD v1.0, use a blank resource (resource="").

• For AAD v2.0, use resource="openid" without any other elements. Optionally you can add "offline_access" as a 2nd element if you want a refresh token as well.

See also the examples below.

Caching

AzureAuth caches tokens based on all the inputs to get_azure_token as listed above. Tokens are cached in a custom, user-specific directory, created with the rappdirs package. On recent Windows versions, this will usually be in the location ⁠C:\\Users\\(username)\\AppData\\Local\\AzureR⁠. On Linux, it will be in ⁠~/.config/AzureR⁠, and on MacOS, it will be in ⁠~/Library/Application Support/AzureR⁠. Alternatively, you can specify the location of the directory in the environment variable R_AZURE_DATA_DIR. Note that a single directory is used for all tokens, and the working directory is not touched (which significantly lessens the risk of accidentally introducing cached tokens into source control).

To list all cached tokens on disk, use list_azure_tokens. This returns a list of token objects, named according to their MD5 hashes.

To delete a cached token, use delete_azure_token. This takes the same inputs as get_azure_token, or you can specify the MD5 hash directly in the hash argument.

To delete all files in the caching directory, use clean_token_directory.

Refreshing

A token object can be refreshed by calling its refresh() method. If the token's credentials contain a refresh token, this is used; otherwise a new access token is obtained by reauthenticating.

Note that in AAD, a refresh token can be used to obtain an access token for any resource or scope that you have permissions for. Thus, for example, you could use a refresh token issued on a request for Azure Resource Manager (⁠https://management.azure.com/⁠) to obtain a new access token for Microsoft Graph (⁠https://graph.microsoft.com/⁠).

To obtain an access token for a new resource, change the object's resource (for an AAD v1.0 token) or scope field (for an AAD v2.0 token) before calling refresh(). If you also want to retain the token for the old resource, you should call the clone() method first to create a copy. See the examples below.

Value

For get_azure_token, an object inheriting from AzureToken. The specific class depends on the authentication flow: AzureTokenAuthCode, AzureTokenDeviceCode, AzureTokenClientCreds, AzureTokenOnBehalfOf, AzureTokenResOwner. For get_managed_token, a similar object of class AzureTokenManaged.

For list_azure_tokens, a list of such objects retrieved from disk.

The actual credentials that are returned from the authorization endpoint can be found in the credentials field, the same as with a httr::Token object. The access token (if present) will be credentials$access_token, and the ID token (if present) will be credentials$id_token. Use these if you are manually constructing a HTTP request and need to insert an "Authorization" header, for example.

See Also

AzureToken, httr::oauth2.0_token, httr::Token, cert_assertion, build_authorization_uri, get_device_creds

Azure Active Directory for developers, Managed identities overview Device code flow on OAuth.com, OAuth 2.0 RFC for the gory details on how OAuth works

Examples

## Not run: 

# authenticate with Azure Resource Manager:
# no user credentials are supplied, so this will use the authorization_code
# method if httpuv is installed, and device_code if not
get_azure_token("https://management.azure.com/", tenant="mytenant", app="app_id")

# you can force a specific authentication method with the auth_type argument
get_azure_token("https://management.azure.com/", tenant="mytenant", app="app_id",
    auth_type="device_code")

# to default to the client_credentials method, supply the app secret as the password
get_azure_token("https://management.azure.com/", tenant="mytenant", app="app_id",
    password="app_secret")

# authenticate to your resource with the resource_owner method: provide your username and password
get_azure_token("https://myresource/", tenant="mytenant", app="app_id",
    username="user", password="abcdefg")

# obtaining multiple tokens: authenticate (interactively) once...
tok0 <- get_azure_token("serviceapp_id", tenant="mytenant", app="clientapp_id",
    auth_type="authorization_code")
# ...then get tokens for each resource (Resource Manager and MS Graph) with on_behalf_of
tok1 <- get_azure_token("https://management.azure.com/", tenant="mytenant", app="serviceapp_id",
    password="serviceapp_secret", on_behalf_of=tok0)
tok2 <- get_azure_token("https://graph.microsoft.com/", tenant="mytenant", app="serviceapp_id",
    password="serviceapp_secret", on_behalf_of=tok0)


# authorization_code flow with app registered in AAD as a web rather than a native client:
# supply the client secret in the password arg
get_azure_token("https://management.azure.com/", "mytenant", "app_id",
    password="app_secret", auth_type="authorization_code")


# use a different redirect URI to the default localhost:1410
get_azure_token("https://management.azure.com/", tenant="mytenant", app="app_id",
    authorize_args=list(redirect_uri="http://localhost:8000"))


# request an AAD v1.0 token for Resource Manager (the default)
token1 <- get_azure_token("https://management.azure.com/", "mytenant", "app_id")

# same request to AAD v2.0, along with a refresh token
token2 <- get_azure_token(c("https://management.azure.com/.default", "offline_access"),
    "mytenant", "app_id", version=2)

# requesting multiple scopes (Microsoft Graph) with AAD 2.0
get_azure_token(c("https://graph.microsoft.com/User.Read.All",
                  "https://graph.microsoft.com/User.ReadWrite.All",
                  "https://graph.microsoft.com/Directory.ReadWrite.All",
                  "offline_access"),
    "mytenant", "app_id", version=2)


# list saved tokens
list_azure_tokens()

# delete a saved token from disk
delete_azure_token(resource="https://myresource/", tenant="mytenant", app="app_id",
    username="user", password="abcdefg")

# delete a saved token by specifying its MD5 hash
delete_azure_token(hash="7ea491716e5b10a77a673106f3f53bfd")


# authenticating for B2C logins (custom AAD host)
get_azure_token("https://mydomain.com", "mytenant", "app_id", "password",
    aad_host="https://mytenant.b2clogin.com/tfp/mytenant.onmicrosoft.com/custom/oauth2")


# authenticating with a certificate
get_azure_token("https://management.azure.com/", "mytenant", "app_id",
    certificate="mycert.pem")

# authenticating with a certificate stored in Azure Key Vault
cert <- AzureKeyVault::key_vault("myvault")$certificates$get("mycert")
get_azure_token("https://management.azure.com/", "mytenant", "app_id",
    certificate=cert)

# get a token valid for 2 hours (default is 1 hour)
get_azure_token("https://management.azure.com/", "mytenant", "app_id",
    certificate=cert_assertion("mycert.pem", duration=2*3600))


# ID token with AAD v1.0
# if you only want an ID token, set the resource to blank ("")
tok <- get_azure_token("", "mytenant", "app_id", use_cache=FALSE)
extract_jwt(tok, "id")

# ID token with AAD v2.0 (recommended)
tok2 <- get_azure_token(c("openid", "offline_access"), "mytenant", "app_id", version=2)
extract_jwt(tok2, "id")


# get a token from within a managed identity (VM, container or service)
get_managed_token("https://management.azure.com/")

# get a token from a managed identity, with a user-defined identity:
# specify one of the identity's object_id, client_id and mi_res_id (Azure resource ID)
# you can get these values via the Azure Portal or Azure CLI
get_managed_token("https://management.azure.com/", token_args=list(
    mi_res_id="/subscriptions/zzzz-zzzz/resourceGroups/resgroupname/..."
))

# use a refresh token from one resource to get an access token for another resource
tok <- get_azure_token("https://myresource", "mytenant", "app_id")
tok2 <- tok$clone()
tok2$resource <- "https://anotherresource"
tok2$refresh()

# same for AAD v2.0
tok <- get_azure_token(c("https://myresource/.default", "offline_access"),
    "mytenant", "app_id", version=2)
tok2 <- tok$clone()
tok2$scope <- c("https://anotherresource/.default", "offline_access")
tok2$refresh()


# manually adding auth header for a HTTP request
tok <- get_azure_token("https://myresource", "mytenant", "app_id")
header <- httr::add_headers(Authorization=paste("Bearer", tok$credentials$access_token))
httr::GET("https://myresource/path/for/call", header, ...)


## End(Not run)