Add ability to programmatically customize profile files

CHANGELOG.next.toml

@@ -53,3 +53,31 @@ of breaking changes and how to resolve them.
 references = ["smithy-rs#1740", "smithy-rs#256"]
 meta = { "breaking" = true, "tada" = false, "bug" = false, "target" = "client" }
 author = "jdisanti"
+
+[[aws-sdk-rust]]
+message = """
+It is now possible to programmatically customize the locations of the profile config/credentials files in `aws-config`:
+```rust
+use aws_config::profile::{ProfileFileCredentialsProvider, ProfileFileRegionProvider};
+use aws_config::profile::profile_file::{ProfileFiles, ProfileFileKind};
+
+let profile_files = ProfileFiles::builder()
+    .with_file(ProfileFileKind::Credentials, "some/path/to/credentials-file")
+    .build();
+let credentials_provider = ProfileFileCredentialsProvider::builder()
+    .profile_files(profile_files.clone())
+    .build();
+let region_provider = ProfileFileRegionProvider::builder()
+    .profile_files(profile_files)
+    .build();
+
+let sdk_config = aws_config::from_env()
+    .credentials_provider(credentials_provider)
+    .region(region_provider)
+    .load()
+    .await;
+```
+"""
+references = ["aws-sdk-rust#237", "smithy-rs#1770"]
+meta = { "breaking" = false, "tada" = true, "bug" = false }
+author = "jdisanti"

aws/rust-runtime/aws-config/src/imds/client.rs

@@ -37,7 +37,7 @@ use tokio::sync::OnceCell;
 
 use crate::connector::expect_connector;
 use crate::imds::client::token::TokenMiddleware;
-use crate::profile::ProfileParseError;
+use crate::profile::credentials::ProfileFileError;
 use crate::provider_config::ProviderConfig;
 use crate::{profile, PKG_VERSION};
 use aws_sdk_sso::config::timeout::TimeoutConfig;
@@ -439,7 +439,7 @@ pub enum BuildError {
     InvalidEndpointMode(InvalidEndpointMode),
 
     /// The AWS Profile (e.g. `~/.aws/config`) was invalid
-    InvalidProfile(ProfileParseError),
+    InvalidProfile(ProfileFileError),
 
     /// The specified endpoint was not a valid URI
     InvalidEndpointUri(InvalidUri),
@@ -626,7 +626,7 @@ impl EndpointSource {
             }
             EndpointSource::Env(env, fs) => {
                 // load an endpoint override from the environment
-                let profile = profile::load(fs, env)
+                let profile = profile::load(fs, env, &Default::default())
                     .await
                     .map_err(BuildError::InvalidProfile)?;
                 let uri_override = if let Ok(uri) = env.get(env::ENDPOINT) {

aws/rust-runtime/aws-config/src/profile/app_name.rs

@@ -5,6 +5,7 @@
 
 //! Load an app name from an AWS profile
 
+use super::profile_file::ProfileFiles;
 use crate::provider_config::ProviderConfig;
 use aws_types::app_name::AppName;
 use aws_types::os_shim_internal::{Env, Fs};
@@ -14,6 +15,8 @@ use aws_types::os_shim_internal::{Env, Fs};
 /// This provider will attempt to shared AWS shared configuration and then read the
 /// `sdk-ua-app-id` property from the active profile.
 ///
+#[doc = include_str!("location_of_profile_files.md")]
+///
 /// # Examples
 ///
 /// **Loads "my-app" as the app name**
@@ -35,6 +38,7 @@ pub struct ProfileFileAppNameProvider {
     fs: Fs,
     env: Env,
     profile_override: Option<String>,
+    profile_files: ProfileFiles,
 }
 
 impl ProfileFileAppNameProvider {
@@ -46,6 +50,7 @@ impl ProfileFileAppNameProvider {
             fs: Fs::real(),
             env: Env::real(),
             profile_override: None,
+            profile_files: Default::default(),
         }
     }
 
@@ -56,7 +61,7 @@ impl ProfileFileAppNameProvider {
 
     /// Parses the profile config and attempts to find an app name.
     pub async fn app_name(&self) -> Option<AppName> {
-        let profile = super::parser::load(&self.fs, &self.env)
+        let profile = super::parser::load(&self.fs, &self.env, &self.profile_files)
             .await
             .map_err(|err| tracing::warn!(err = %err, "failed to parse profile"))
             .ok()?;
@@ -82,6 +87,7 @@ impl ProfileFileAppNameProvider {
 pub struct Builder {
     config: Option<ProviderConfig>,
     profile_override: Option<String>,
+    profile_files: Option<ProfileFiles>,
 }
 
 impl Builder {
@@ -104,6 +110,7 @@ impl Builder {
             env: conf.env(),
             fs: conf.fs(),
             profile_override: self.profile_override,
+            profile_files: self.profile_files.unwrap_or_default(),
         }
     }
 }

aws/rust-runtime/aws-config/src/profile/credentials.rs

@@ -22,22 +22,21 @@
 //! - `exec` which contains a chain representation of providers to implement passing bootstrapped credentials
 //! through a series of providers.
 
+use crate::profile::credentials::exec::named::NamedProviderFactory;
+use crate::profile::credentials::exec::{ClientConfiguration, ProviderChain};
+use crate::profile::parser::ProfileParseError;
+use crate::profile::profile_file::ProfileFiles;
+use crate::profile::Profile;
+use crate::provider_config::ProviderConfig;
+use aws_types::credentials::{self, future, CredentialsError, ProvideCredentials};
 use std::borrow::Cow;
 use std::collections::HashMap;
 use std::error::Error;
 use std::fmt::{Display, Formatter};
+use std::path::PathBuf;
 use std::sync::Arc;
-
-use aws_types::credentials::{self, future, CredentialsError, ProvideCredentials};
-
 use tracing::Instrument;
 
-use crate::profile::credentials::exec::named::NamedProviderFactory;
-use crate::profile::credentials::exec::{ClientConfiguration, ProviderChain};
-use crate::profile::parser::ProfileParseError;
-use crate::profile::Profile;
-use crate::provider_config::ProviderConfig;
-
 mod exec;
 mod repr;
 
@@ -142,29 +141,14 @@ impl ProvideCredentials for ProfileFileCredentialsProvider {
 ///
 /// SSO can also be used as a source profile for assume role chains.
 ///
-/// ## Location of Profile Files
-/// * The location of the config file will be loaded from the `AWS_CONFIG_FILE` environment variable
-/// with a fallback to `~/.aws/config`
-/// * The location of the credentials file will be loaded from the `AWS_SHARED_CREDENTIALS_FILE`
-/// environment variable with a fallback to `~/.aws/credentials`
-///
-/// ## Home directory resolution
-/// Home directory resolution is implemented to match the behavior of the CLI & Python. `~` is only
-/// used for home directory resolution when it:
-/// - Starts the path
-/// - Is followed immediately by `/` or a platform specific separator. (On windows, `~/` and `~\` both
-///   resolve to the home directory.
-///
-/// When determining the home directory, the following environment variables are checked:
-/// - `HOME` on all platforms
-/// - `USERPROFILE` on Windows
-/// - The concatenation of `HOMEDRIVE` and `HOMEPATH` on Windows (`$HOMEDRIVE$HOMEPATH`)
+#[doc = include_str!("location_of_profile_files.md")]
 #[derive(Debug)]
 pub struct ProfileFileCredentialsProvider {
     factory: NamedProviderFactory,
     client_config: ClientConfiguration,
     provider_config: ProviderConfig,
     profile_override: Option<String>,
+    profile_files: ProfileFiles,
 }
 
 impl ProfileFileCredentialsProvider {
@@ -178,6 +162,7 @@ impl ProfileFileCredentialsProvider {
             &self.provider_config,
             &self.factory,
             self.profile_override.as_deref(),
+            &self.profile_files,
         )
         .await
         .map_err(|err| match err {
@@ -225,6 +210,13 @@ impl ProfileFileCredentialsProvider {
     }
 }
 
+#[doc(hidden)]
+#[derive(Debug)]
+pub struct CouldNotReadProfileFile {
+    pub(crate) path: PathBuf,
+    pub(crate) cause: std::io::Error,
+}
+
 /// An Error building a Credential source from an AWS Profile
 #[derive(Debug)]
 #[non_exhaustive]
@@ -283,6 +275,10 @@ pub enum ProfileFileError {
         /// The name of the provider
         name: String,
     },
+
+    /// A custom profile file location didn't exist or could not be read
+    #[non_exhaustive]
+    CouldNotReadProfileFile(CouldNotReadProfileFile),
 }
 
 impl ProfileFileError {
@@ -326,6 +322,13 @@ impl Display for ProfileFileError {
                 "profile `{}` did not contain credential information",
                 profile
             ),
+            ProfileFileError::CouldNotReadProfileFile(details) => {
+                write!(
+                    f,
+                    "Failed to read custom profile file at {:?}",
+                    details.path
+                )
+            }
         }
     }
 }
@@ -334,16 +337,24 @@ impl Error for ProfileFileError {
     fn source(&self) -> Option<&(dyn Error + 'static)> {
         match self {
             ProfileFileError::CouldNotParseProfile(err) => Some(err),
+            ProfileFileError::CouldNotReadProfileFile(details) => Some(&details.cause),
             _ => None,
         }
     }
 }
 
+impl From<ProfileParseError> for ProfileFileError {
+    fn from(err: ProfileParseError) -> Self {
+        ProfileFileError::CouldNotParseProfile(err)
+    }
+}
+
 /// Builder for [`ProfileFileCredentialsProvider`]
 #[derive(Debug, Default)]
 pub struct Builder {
     provider_config: Option<ProviderConfig>,
     profile_override: Option<String>,
+    profile_files: Option<ProfileFiles>,
     custom_providers: HashMap<Cow<'static, str>, Arc<dyn ProvideCredentials>>,
 }
 
@@ -409,6 +420,12 @@ impl Builder {
         self
     }
 
+    /// Set the profile file that should be used by the [`ProfileFileCredentialsProvider`]
+    pub fn profile_files(mut self, profile_files: ProfileFiles) -> Self {
+        self.profile_files = Some(profile_files);
+        self
+    }
+
     /// Builds a [`ProfileFileCredentialsProvider`]
     pub fn build(self) -> ProfileFileCredentialsProvider {
         let build_span = tracing::debug_span!("build_profile_provider");
@@ -453,6 +470,7 @@ impl Builder {
             },
             provider_config: conf,
             profile_override: self.profile_override,
+            profile_files: self.profile_files.unwrap_or_default(),
         }
     }
 }
@@ -461,13 +479,10 @@ async fn build_provider_chain(
     provider_config: &ProviderConfig,
     factory: &NamedProviderFactory,
     profile_override: Option<&str>,
+    profile_files: &ProfileFiles,
 ) -> Result<ProviderChain, ProfileFileError> {
-    let profile_set = super::parser::load(&provider_config.fs(), &provider_config.env())
-        .await
-        .map_err(|err| {
-            tracing::warn!(err = %err, "failed to parse profile");
-            ProfileFileError::CouldNotParseProfile(err)
-        })?;
+    let profile_set =
+        super::parser::load(&provider_config.fs(), &provider_config.env(), profile_files).await?;
     let repr = repr::resolve_chain(&profile_set, profile_override)?;
     tracing::info!(chain = ?repr, "constructed abstract provider from config file");
     exec::ProviderChain::from_repr(provider_config, repr, factory)

aws/rust-runtime/aws-config/src/profile/location_of_profile_files.md

@@ -0,0 +1,19 @@
+## Location of Profile Files
+* The location of the config file will be loaded from the `AWS_CONFIG_FILE` environment variable
+with a fallback to `~/.aws/config`
+* The location of the credentials file will be loaded from the `AWS_SHARED_CREDENTIALS_FILE`
+environment variable with a fallback to `~/.aws/credentials`
+
+The location of these files can also be customized programmatically using [`ProfileFiles`](crate::profile::profile_file::ProfileFiles).
+
+## Home directory resolution
+Home directory resolution is implemented to match the behavior of the CLI & Python. `~` is only
+used for home directory resolution when it:
+- Starts the path
+- Is followed immediately by `/` or a platform specific separator. (On windows, `~/` and `~\` both
+  resolve to the home directory.
+
+When determining the home directory, the following environment variables are checked:
+- `HOME` on all platforms
+- `USERPROFILE` on Windows
+- The concatenation of `HOMEDRIVE` and `HOMEPATH` on Windows (`$HOMEDRIVE$HOMEPATH`)

aws/rust-runtime/aws-config/src/profile/mod.rs

@@ -20,6 +20,7 @@ pub use parser::{load, Profile, ProfileSet, Property};
 
 pub mod app_name;
 pub mod credentials;
+pub mod profile_file;
 pub mod region;
 pub mod retry_config;