pharia-common 0.4.0

//! **IAM** is short for **I**dentity **A**ccess **M**anagement. This module contains opinionated
//! adapters to connect to the internal Pharia IAM solution.

use std::{borrow::Cow, fmt::Display};

use reqwest::{Client, StatusCode};
use reqwest_middleware::{ClientBuilder, ClientWithMiddleware};
use serde::{Deserialize, Serialize};

/// URL of IAM in our production environment
pub const IAM_PRODUCTION_URL: &str = "https://pharia-iam.product.pharia.com";

pub const IAM_STAGE_URL: &str = "https://pharia-iam.stage.product.pharia.com";

/// Client forPharia **I**dentity **A**ccess **M**anagement. Authenticate and authorize users.
#[derive(Clone, Debug)]
pub struct IamClient {
    /// Environment specific URL to Pharia IAM. E.g. <https://pharia-iam.product.pharia.com>
    base_url: String,
    /// Used for sending the http requests. We are using `ClientWithMiddleware` to allow for VCR
    /// recording in tests.
    http_client: ClientWithMiddleware,
}

impl IamClient {
    /// Construct a new client using the respective IAM instance. E.g. [`IAM_PRODUCTION_URL`]
    pub fn new(base_url: String) -> Self {
        let client = Client::builder().use_rustls_tls().build().expect(
            "Must be able to initialize TLS backend and resolver must be able to load system \
            configuration.",
        );

        let http_client: ClientWithMiddleware = ClientBuilder::new(client).build();

        Self {
            base_url,
            http_client,
        }
    }

    #[cfg(test)]
    pub fn with_vcr(base_url: String, path_to_cassette: std::path::PathBuf) -> Self {
        let cassette_does_exist = path_to_cassette.is_file();
        let vcr_mode = if cassette_does_exist {
            reqwest_vcr::VCRMode::Replay
        } else {
            reqwest_vcr::VCRMode::Record
        };

        let middleware = reqwest_vcr::VCRMiddleware::try_from(path_to_cassette)
            .unwrap()
            .with_mode(vcr_mode)
            .with_modify_request(|request| {
                if let Some(header) = request.headers.get_mut("authorization") {
                    *header = vec!["TOKEN_REMOVED".to_owned()];
                }
            });

        IamClient::with_middleware(base_url, middleware)
    }

    #[cfg(test)]
    fn with_middleware(base_url: String, middleware: impl reqwest_middleware::Middleware) -> Self {
        let client = Client::builder().use_rustls_tls().build().expect(
            "Must be able to initialize TLS backend and resolver must be able to load system \
            configuration.",
        );

        let http_client: ClientWithMiddleware = ClientBuilder::new(client).with(middleware).build();

        IamClient {
            base_url,
            http_client,
        }
    }

    /// One stop shop for both authentication and asking a set of permissions. While this method
    /// returns a subset of permissions to which matches the privileges of the user it does not
    /// perform the authorization check. Call `authorize`
    ///
    /// # Parameters
    ///
    /// * `token`: Service or user token used for authentication.
    /// * `permissions`: A list of all permissions you are interested in. The response will contain
    ///   the subset of these permissions which are privileges the user has.
    pub async fn check_user<'a>(
        &self,
        token: impl Display,
        permissions: &'a [Permission<'a>],
    ) -> Result<UserInfoAndPermissions, CheckUserError> {
        let request_body = CheckUserRequestBody { permissions };

        let response = self
            .http_client
            .post(format!("{base_url}/check_user", base_url = self.base_url))
            .bearer_auth(token)
            .json(&request_body)
            .send()
            .await
            .map_err(|e| CheckUserError::ConnectionError(e.into()))?;

        // A long standing quirk of the HTTP standard: Unauthorized 401 actually means
        // "unauthenticated". We consider this a domain specific logic error, rather than a runtime
        // error, which should be fixed with retry. Therfore we categorize this error differently
        // the other connection errors
        if response.status() == StatusCode::UNAUTHORIZED {
            return Err(CheckUserError::Unauthenticated);
        }

        if response.status() == StatusCode::UNPROCESSABLE_ENTITY {
            use anyhow::anyhow;
            eprintln!("{}", response.text().await.unwrap());
            return Err(CheckUserError::ConnectionError(anyhow!(
                "Unprocessable entity"
            )));
        }

        // Map all other thing to ConnectionError
        response
            .error_for_status_ref()
            .map_err(|e| CheckUserError::ConnectionError(e.into()))?;

        let user_info = response
            .json()
            .await
            .map_err(|e| CheckUserError::ConnectionError(e.into()))?;

        Ok(user_info)
    }

    /// Same as `check_user` but also performs the authorization check and fails if the user is not
    /// authorized.
    ///
    /// # Parameters
    ///
    /// * `token`: Service or user token used for authentication.
    /// * `permissions`: A list of all permissions you are interested in. The response will contain
    ///   the subset of these permissions which are privileges the user has.
    ///
    /// Example: Check if the user has the `AccessAssistant` permission.
    ///
    /// ```
    /// use pharia_common::{Permission, IamClient, AuthorizationError, IAM_PRODUCTION_URL};
    ///
    /// pub async fn authorize(token: &str) -> Result<(), AuthorizationError> {
    ///     let iam = IamClient::new(IAM_PRODUCTION_URL.to_owned());
    ///     let permissions = [Permission::AccessAssistant];
    ///     let user_info = iam.authorize(token, &permissions).await?;
    ///     Ok(())
    /// }
    /// ```
    pub async fn authorize<'a>(
        &self,
        token: impl Display,
        permissions: &'a [Permission<'a>],
    ) -> Result<UserInfoAndPermissions, AuthorizationError> {
        let user_info = self.check_user(token, permissions).await?;
        if user_info.permissions == permissions {
            Ok(user_info)
        } else {
            Err(AuthorizationError::Unauthorized)
        }
    }
}

/// Body of the the IAM `/check_user` route. The token is not passed in the body but in the
/// authorization header.
#[derive(Serialize)]
struct CheckUserRequestBody<'a> {
    /// A list of permissions to query for the specific user.
    permissions: &'a [Permission<'a>],
}

/// Returned by [`IamClient::check_user`]. Contains information describing the user as well as the
/// union of the queried permissions and the privileges of the user.
#[derive(Deserialize, PartialEq, Eq, Debug)]
pub struct UserInfoAndPermissions {
    /// Unique ID of the User
    pub sub: String,
    /// Email of the user. `None` for Service users
    pub email: Option<String>,
    /// May be `None` for Service Users
    pub email_verified: Option<bool>,
    /// List of requested permissions, which are privieleges of the User Service. They are in the
    /// same order as in the query
    pub permissions: Vec<Permission<'static>>,
}

/// An error returned by [`IamClient::check_user`]. Note that this does **not** include
/// unauthorized. To check for authorization inspect the permissions of [`UserInfoAndPermissions`]
#[derive(thiserror::Error, Debug)]
pub enum CheckUserError {
    #[error("User is Unauthenticated. Token is invalid")]
    Unauthenticated,
    #[error("User could not be authenticated due to connectivity issue:\n{0:#}")]
    ConnectionError(#[source] anyhow::Error),
}

#[derive(Serialize, Deserialize, Debug, PartialEq, Eq, Clone, Hash)]
#[serde(tag = "permission")]
pub enum Permission<'a> {
    AccessAssistant,
    NuminousAccess,
    /// The kernel uses this permission to authorize skill execution
    KernelAccess,
    /// Used by inference to decide wether a user is authorized to perform any kind of inference
    /// requests.
    ExecuteJobs,
    /// Is this user allowed to use this model? "*" Can be used as a model name in order to indicate
    /// access to all models.
    AccessModel {
        model: Cow<'a, str>,
    },
    HasRelation {
        relation: Cow<'a, str>,
        object: Cow<'a, str>,
    },
}

#[derive(thiserror::Error, Debug)]
pub enum AuthorizationError {
    #[error("User is Unauthenticated. Token is invalid")]
    Unauthenticated,
    #[error("Unauthorized")]
    Unauthorized,
    #[error("User could not be authenticated due to connectivity issue:\n{0:#}")]
    ConnectionError(#[source] anyhow::Error),
}

impl From<CheckUserError> for AuthorizationError {
    fn from(err: CheckUserError) -> Self {
        match err {
            CheckUserError::Unauthenticated => AuthorizationError::Unauthenticated,
            CheckUserError::ConnectionError(err) => AuthorizationError::ConnectionError(err),
        }
    }
}

#[cfg(test)]
mod tests {
    use dotenvy::dotenv;
    use std::{borrow::Cow, env, path::PathBuf};

    use crate::iam::IAM_STAGE_URL;

    use super::{
        CheckUserError, IAM_PRODUCTION_URL, IamClient, Permission, UserInfoAndPermissions,
    };

    #[tokio::test]
    async fn valid_user_token() {
        // We are using cassets to record the request. This makes the test easy to execute even
        // without a connection to Pharia. Additionally it allows us to execute the test even
        // without the specific token of the user who recorded it at hand.
        let mut cassette_path = PathBuf::from(env!("CARGO_MANIFEST_DIR"));
        cassette_path.push("tests/cassettes/valid_user_token.vcr.json");

        // Given a client
        let client = IamClient::with_vcr(IAM_PRODUCTION_URL.to_owned(), cassette_path);

        // When sending a check user request with a valid token
        let response = client.check_user(token(), &[]).await.unwrap();

        // Then we recevie an answer, identifying the user
        let expected = UserInfoAndPermissions {
            sub: "295355180126307110".to_owned(),
            email: Some("markus.klein@aleph-alpha.com".to_owned()),
            email_verified: Some(true),
            permissions: vec![],
        };
        assert_eq!(expected, response);
    }

    #[tokio::test]
    async fn invalid_user_token() {
        // We are using cassets to record the request. This makes the test easy to execute even
        // without a connection to Pharia. Additionally it allows us to execute the test even
        // without the specific token of the user who recorded it at hand.
        let mut cassette_path = PathBuf::from(env!("CARGO_MANIFEST_DIR"));
        cassette_path.push("tests/cassettes/invalid_user_token.vcr.json");

        // Given an invalid Pharia User Token
        let token = "I-AM-AN-INVALID-TOKEN";
        let client = IamClient::with_vcr(IAM_PRODUCTION_URL.to_owned(), cassette_path);

        // When sending a check user request
        let result = client.check_user(token, &[]).await;

        // Then the user is unauthenticated
        assert!(matches!(result, Err(CheckUserError::Unauthenticated)))
    }

    #[tokio::test]
    async fn asking_for_permissions() {
        // We are using cassets to record the request. This makes the test easy to execute even
        // without a connection to Pharia. Additionally it allows us to execute the test even
        // without the specific token of the user who recorded it at hand.
        let mut cassette_path = PathBuf::from(env!("CARGO_MANIFEST_DIR"));
        cassette_path.push("tests/cassettes/asking_for_permissions.vcr.json");

        // Given a client
        let client = IamClient::with_vcr(IAM_PRODUCTION_URL.to_owned(), cassette_path);
        let permissions = [
            Permission::KernelAccess,
            Permission::ExecuteJobs,
            Permission::AccessAssistant,
            Permission::NuminousAccess,
            Permission::AccessModel { model: "*".into() },
        ];

        // When sending a check user request with a token authorized for all permission it is
        // asking for.
        let response = client.check_user(token(), &permissions).await.unwrap();

        // Then we recevie an answer, identifying the user and all the permissions are visible
        // in the answer.
        let expected = UserInfoAndPermissions {
            sub: "295355180126307110".to_owned(),
            email: Some("markus.klein@aleph-alpha.com".to_owned()),
            email_verified: Some(true),
            // It seems the IAM backend maintains order. So this assertion works.
            permissions: permissions.to_vec(),
        };
        assert_eq!(expected, response);
    }

    #[tokio::test]
    async fn authorize() {
        // We are using cassets to record the request. This makes the test easy to execute even
        // without a connection to Pharia. Additionally it allows us to execute the test even
        // without the specific token of the user who recorded it at hand.
        let mut cassette_path = PathBuf::from(env!("CARGO_MANIFEST_DIR"));
        cassette_path.push("tests/cassettes/authorize.vcr.json");

        // Given a client
        let client = IamClient::with_vcr(IAM_PRODUCTION_URL.to_owned(), cassette_path);
        let permissions = [
            Permission::KernelAccess,
            Permission::ExecuteJobs,
            Permission::AccessAssistant,
            Permission::NuminousAccess,
            Permission::AccessModel { model: "*".into() },
        ];

        // When sending a check user request with a token authorized for all permission it is
        // asking for.
        let response = client.authorize(token(), &permissions).await.unwrap();

        // Then we recevie an answer, identifying the user and all the permissions are visible
        // in the answer.
        let expected = UserInfoAndPermissions {
            sub: "295355180126307110".to_owned(),
            email: Some("markus.klein@aleph-alpha.com".to_owned()),
            email_verified: Some(true),
            // It seems the IAM backend maintains order. So this assertion works.
            permissions: permissions.to_vec(),
        };
        assert_eq!(expected, response);
    }

    #[tokio::test]
    async fn asking_for_permissions_as_service() {
        // We are using cassets to record the request. This makes the test easy to execute even
        // without a connection to Pharia. Additionally it allows us to execute the test even
        // without the specific token of the user who recorded it at hand.
        let mut cassette_path = PathBuf::from(env!("CARGO_MANIFEST_DIR"));
        cassette_path.push("tests/cassettes/asking_for_permissions_as_service.vcr.json");

        // Given a client
        let client = IamClient::with_vcr(IAM_PRODUCTION_URL.to_owned(), cassette_path);
        let permissions = [Permission::AccessAssistant, Permission::NuminousAccess];

        // When sending a check user request with a token authorized for all permission it is
        // asking for.
        let response = client
            .check_user(service_token(), &permissions)
            .await
            .unwrap();

        // Then we recevie an answer, identifying the user and all the permissions are visible
        // in the answer.
        let expected = UserInfoAndPermissions {
            sub: "336362361919115278".to_owned(),
            email: None,
            email_verified: None,
            // It seems the IAM backend maintains order. So this assertion works.
            permissions: [].to_vec(), // permissions.to_vec(),
        };
        assert_eq!(expected, response);
    }

    /// The [`Permission`]s enum is not exhaustive. If only testing as admin you get every, even
    /// made up ones, mirrored. So we want to have a test to verify that permissions do exist, by
    /// authorizing for them, with a
    #[tokio::test]
    async fn verify_predefined_permissions() {
        let mut cassette_path = PathBuf::from(env!("CARGO_MANIFEST_DIR"));
        cassette_path.push("tests/cassettes/verify_predefined_permissions.vcr.json");

        // Given a client
        let client = IamClient::with_vcr(IAM_STAGE_URL.to_owned(), cassette_path);
        let permissions = [
            Permission::AccessAssistant,
            Permission::ExecuteJobs,
            Permission::KernelAccess,
            Permission::NuminousAccess,
            Permission::AccessModel {
                model: Cow::Borrowed("*"),
            },
        ];

        // When sending a check user request with a token authorized for all permission it is
        // asking for.
        let result = client
            .authorize(stage_non_admin_token(), &permissions)
            .await;

        // Then we recevie an answer, identifying the user and all the permissions are visible
        // in the answer.
        eprintln!("{:?}", result);
        assert!(result.is_ok());
    }

    /// Service token used for recording cassettes
    ///
    /// Credentials: pharia-internal-rs-test
    /// The user (developers) token from the environment
    fn service_token() -> String {
        _ = dotenv();
        env::var("PHARIA_AI_SERVICE_TOKEN").unwrap_or_else(|_| "DUMMY".to_owned())
    }

    /// The user (developers) token from the environment
    fn token() -> String {
        _ = dotenv();
        env::var("PHARIA_AI_TOKEN").unwrap_or_else(|_| "DUMMY".to_owned())
    }

    /// The user (developers) token from the environment
    fn stage_non_admin_token() -> String {
        _ = dotenv();
        env::var("PHARIA_STAGE_NON_ADMIN").unwrap_or_else(|_| "DUMMY".to_owned())
    }
}