398 lines
16 KiB
Zig
398 lines
16 KiB
Zig
//! Implements the standard credential chain:
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//! 1. Environment variables
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//! 2. Web identity token from STS
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//! 3. Credentials/config files
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//! 4. ECS Container credentials, using AWS_CONTAINER_CREDENTIALS_RELATIVE_URI
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//! 5. EC2 instance profile credentials
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const std = @import("std");
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const builtin = @import("builtin");
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const auth = @import("aws_authentication.zig");
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const log = std.log.scoped(.aws_credentials);
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pub const Profile = struct {
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/// Credential file. Defaults to AWS_SHARED_CREDENTIALS_FILE or ~/.aws/credentials
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credential_file: ?[]const u8 = null,
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/// Config file. Defaults to AWS_CONFIG_FILE or ~/.aws/config
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config_file: ?[]const u8 = null,
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/// Config file. Defaults to AWS_PROFILE or default
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profile_name: ?[]const u8 = null,
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};
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pub const Options = struct {
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profile: Profile = .{},
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};
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pub fn getCredentials(allocator: std.mem.Allocator, options: Options) !auth.Credentials {
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if (try getEnvironmentCredentials(allocator)) |cred| return cred;
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// TODO: 2-5
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// Note that boto and Java disagree on where this fits in the order
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if (try getWebIdentityToken(allocator)) |cred| return cred;
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if (try getProfileCredentials(allocator, options.profile)) |cred| return cred;
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return error.NotImplemented;
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}
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fn getEnvironmentCredentials(allocator: std.mem.Allocator) !?auth.Credentials {
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const secret_key = (try getEnvironmentVariable(allocator, "AWS_SECRET_ACCESS_KEY")) orelse return null;
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defer allocator.free(secret_key); //yes, we're not zeroing. But then, the secret key is in an environment var anyway
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const mutable_key = try allocator.dupe(u8, secret_key);
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// Use cross-platform API (requires allocation)
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return auth.Credentials.init(
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allocator,
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(try getEnvironmentVariable(allocator, "AWS_ACCESS_KEY_ID")) orelse return null,
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mutable_key,
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(try getEnvironmentVariable(allocator, "AWS_SESSION_TOKEN")) orelse
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try getEnvironmentVariable(allocator, "AWS_SECURITY_TOKEN"), // Security token is backward compat only
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);
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}
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fn getEnvironmentVariable(allocator: std.mem.Allocator, key: []const u8) !?[]const u8 {
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return std.process.getEnvVarOwned(allocator, key) catch |e| switch (e) {
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std.process.GetEnvVarOwnedError.EnvironmentVariableNotFound => return null,
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else => return e,
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};
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}
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fn getWebIdentityToken(allocator: std.mem.Allocator) !?auth.Credentials {
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_ = allocator;
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// This API does not require signing. We can just use zfetch to
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// shoot a raw request over.
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// https://docs.aws.amazon.com/STS/latest/APIReference/API_AssumeRoleWithWebIdentity.html
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// https://github.com/boto/boto3/blob/85b975af30c408f93b654a21930218edd58336ad/docs/source/guide/credentials.rst#assume-role-with-web-identity-provider
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// https://github.com/aws/aws-sdk-java-v2/blob/master/core/auth/src/main/java/software/amazon/awssdk/auth/credentials/WebIdentityTokenFileCredentialsProvider.java
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// TODO: implement
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return null;
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}
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fn getProfileCredentials(allocator: std.mem.Allocator, options: Profile) !?auth.Credentials {
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var default_path: ?[]const u8 = null;
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defer if (default_path) |p| allocator.free(p);
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const creds_file_path = try filePath(
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allocator,
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options.credential_file,
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"AWS_SHARED_CREDENTIALS_FILE",
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default_path,
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"credentials",
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);
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defer allocator.free(creds_file_path.evaluated_path);
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default_path = default_path orelse creds_file_path.home;
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const config_file_path = try filePath(
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allocator,
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options.credential_file,
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"AWS_SHARED_CREDENTIALS_FILE",
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default_path,
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"config",
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);
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defer allocator.free(config_file_path.evaluated_path);
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default_path = default_path orelse config_file_path.home;
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// Get active profile
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const profile = (try getEnvironmentVariable(allocator, "AWS_PROFILE")) orelse
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try allocator.dupe(u8, "default");
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defer allocator.free(profile);
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log.debug("Looking for file credentials using profile '{s}'", .{profile});
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log.debug("Checking credentials file: {s}", .{creds_file_path.evaluated_path});
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const credentials_file = std.fs.openFileAbsolute(creds_file_path.evaluated_path, .{}) catch null;
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defer if (credentials_file) |f| f.close();
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// It's much more likely that we'll find credentials in the credentials file
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// so we'll try that first
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const creds_file_creds = try credsForFile(allocator, credentials_file, profile);
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var conf_file_creds = PartialCredentials{};
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if (creds_file_creds.access_key == null or creds_file_creds.secret_key == null) {
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log.debug("Checking config file: {s}", .{config_file_path.evaluated_path});
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const config_file = std.fs.openFileAbsolute(creds_file_path.evaluated_path, .{}) catch null;
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defer if (config_file) |f| f.close();
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conf_file_creds = try credsForFile(allocator, config_file, profile);
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}
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const access_key = keyFrom(allocator, creds_file_creds.access_key, conf_file_creds.access_key);
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const secret_key = keyFrom(allocator, creds_file_creds.secret_key, conf_file_creds.secret_key);
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defer if (secret_key) |k| allocator.free(k);
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if (access_key == null or secret_key == null) {
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const partial = access_key != null or secret_key != null;
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if (partial) {
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log.warn("Could not find credentials in file (partial creds detected)", .{});
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} else {
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log.info("Could not find credentials in file", .{});
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}
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if (access_key) |k| allocator.free(k);
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return null;
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}
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log.debug("Got full credentials from filesystem. Access key: {s}", .{access_key.?});
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return auth.Credentials.init(
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allocator,
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access_key.?,
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try allocator.dupe(u8, secret_key.?),
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null,
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);
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}
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fn keyFrom(allocator: std.mem.Allocator, priority_1: ?[]const u8, priority_2: ?[]const u8) ?[]const u8 {
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if (priority_1) |p1| {
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if (priority_2) |p2| allocator.free(p2);
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return p1;
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}
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return priority_2;
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}
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// We could conceivably find different portions of the creds in different
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// files, so let's be super-loose here
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const PartialCredentials = struct {
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access_key: ?[]const u8 = null,
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secret_key: ?[]const u8 = null,
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};
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fn credsForFile(allocator: std.mem.Allocator, file: ?std.fs.File, profile: []const u8) !PartialCredentials {
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if (file == null) return PartialCredentials{};
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const text = try file.?.readToEndAlloc(allocator, std.math.maxInt(usize));
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defer allocator.free(text);
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const partial_creds = try credsForText(text, profile);
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var ak: ?[]const u8 = null;
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if (partial_creds.access_key) |k|
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ak = try allocator.dupe(u8, k);
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var sk: ?[]const u8 = null;
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if (partial_creds.secret_key) |k|
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sk = try allocator.dupe(u8, k);
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return PartialCredentials{
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.access_key = ak,
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.secret_key = sk,
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};
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}
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const LineIterator = struct {
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text: []const u8,
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inx: usize = 0,
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const Self = @This();
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pub fn init(text: []const u8) Self {
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return .{
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.text = text,
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.inx = 0,
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};
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}
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pub fn next(self: *Self) ?[]const u8 {
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if (self.inx >= self.text.len) return null;
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var current = self.inx;
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var start = self.inx;
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for (self.text[self.inx..]) |c, i| {
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if (c == '\n') {
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// log.debug("got \\n: {d}", .{i});
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current += i + 1;
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break;
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}
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}
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// log.debug("{d}:{d}", .{ current, self.inx });
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if (current != self.inx) {
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self.inx = current;
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} else { // no \n found
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self.inx = self.text.len + 1; // add one to capture the last char in return
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}
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return self.text[start .. self.inx - 1];
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}
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};
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fn credsForText(text: []const u8, profile: []const u8) !PartialCredentials {
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var lines = LineIterator.init(text);
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var is_in_profile = false;
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var was_in_profile = false;
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var done = false;
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var creds: [2]?[]const u8 = [_]?[]const u8{ null, null };
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while (lines.next()) |line| {
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// log.debug("line: {s}", .{line});
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var section_start: ?usize = 0;
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for (line) |c, i| {
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switch (c) {
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'#' => break,
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'[' => section_start = i + 1,
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']' => {
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if (section_start) |s| {
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const current_section = line[s..i];
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log.debug("got section: {s}", .{current_section});
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is_in_profile = std.ascii.eqlIgnoreCase(current_section, profile);
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if (was_in_profile and !is_in_profile) {
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done = true;
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break;
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}
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was_in_profile = is_in_profile;
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break; // got what we need from this line
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}
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},
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'=' => {
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if (!is_in_profile) continue;
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const key = std.mem.trim(u8, line[0..i], " \t"); // other whitespace we care about?
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log.debug("got key: {s}", .{key});
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for (&[_][]const u8{
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"aws_access_key_id",
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"aws_secret_access_key",
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}) |needle, inx| {
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if (std.ascii.eqlIgnoreCase(key, needle)) {
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// TODO: Trim this out
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creds[inx] = trim(line[i + 1 ..]);
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}
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}
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},
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else => {},
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}
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}
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if (done) {
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log.debug("no longer in target section: bailing", .{});
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break;
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}
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}
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log.debug("done parsing text", .{});
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return PartialCredentials{
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.access_key = creds[0],
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.secret_key = creds[1],
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};
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}
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fn trim(text: []const u8) []const u8 {
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// " myval # yo";
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var start: ?usize = null;
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var end: ?usize = null;
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for (text) |c, i| switch (c) {
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' ', '\t' => {},
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'#' => return trimmed(text, start, end),
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else => {
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if (start == null) start = i;
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end = i + 1;
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},
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};
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return trimmed(text, start, end);
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}
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fn trimmed(text: []const u8, start: ?usize, end: ?usize) []const u8 {
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if (start == null) return "";
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if (end == null) return text[start.?..];
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return text[start.?..end.?];
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}
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fn filePath(
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allocator: std.mem.Allocator,
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specified_path: ?[]const u8,
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env_var_name: []const u8,
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config_dir: ?[]const u8,
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config_file_name: []const u8,
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) !EvaluatedPath {
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if (specified_path) |p| return EvaluatedPath{ .evaluated_path = try allocator.dupe(u8, p) };
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// Not specified. Check environment variable, otherwise, hard coded default
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if (try getEnvironmentVariable(allocator, env_var_name)) |v| return EvaluatedPath{ .evaluated_path = v };
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// Not in environment variable either. Go fish
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return try getDefaultPath(allocator, config_dir, ".aws", config_file_name);
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}
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const EvaluatedPath = struct {
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home: ?[]const u8 = null,
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evaluated_path: []const u8,
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};
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fn getDefaultPath(allocator: std.mem.Allocator, home_dir: ?[]const u8, dir: []const u8, file: []const u8) !EvaluatedPath {
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var home = home_dir orelse try getHomeDir(allocator);
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log.debug("Home directory: {s}", .{home});
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const rc = try std.fs.path.join(allocator, &[_][]const u8{ home, dir, file });
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log.debug("Path evaluated as: {s}", .{rc});
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return EvaluatedPath{ .home = home, .evaluated_path = rc };
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}
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fn getHomeDir(allocator: std.mem.Allocator) ![]const u8 {
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switch (builtin.os.tag) {
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.windows => {
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var dir_path_ptr: [*:0]u16 = undefined;
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// https://docs.microsoft.com/en-us/windows/win32/shell/knownfolderid
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const FOLDERID_Profile = std.os.windows.GUID.parse("{5E6C858F-0E22-4760-9AFE-EA3317B67173}");
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switch (std.os.windows.shell32.SHGetKnownFolderPath(
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&FOLDERID_Profile,
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std.os.windows.KF_FLAG_CREATE,
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null,
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&dir_path_ptr,
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)) {
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std.os.windows.S_OK => {
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defer std.os.windows.ole32.CoTaskMemFree(@ptrCast(*anyopaque, dir_path_ptr));
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const global_dir = std.unicode.utf16leToUtf8Alloc(allocator, std.mem.sliceTo(dir_path_ptr, 0)) catch |err| switch (err) {
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error.UnexpectedSecondSurrogateHalf => return error.HomeDirUnavailable,
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error.ExpectedSecondSurrogateHalf => return error.HomeDirUnavailable,
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error.DanglingSurrogateHalf => return error.HomeDirUnavailable,
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error.OutOfMemory => return error.OutOfMemory,
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};
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return global_dir;
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// defer allocator.free(global_dir);
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},
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std.os.windows.E_OUTOFMEMORY => return error.OutOfMemory,
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else => return error.HomeDirUnavailable,
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}
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},
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.macos, .linux, .freebsd, .netbsd, .dragonfly, .openbsd, .solaris => {
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const home_dir = std.os.getenv("HOME") orelse {
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// TODO look in /etc/passwd
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return error.HomeDirUnavailable;
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};
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return allocator.dupe(u8, home_dir);
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},
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// Code from https://github.com/ziglang/zig/blob/9f9f215305389c08a21730859982b68bf2681932/lib/std/fs/get_app_data_dir.zig
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// be_user_settings magic number is probably different for home directory
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// .haiku => {
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// var dir_path_ptr: [*:0]u8 = undefined;
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// // TODO look into directory_which
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// const be_user_settings = 0xbbe;
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// const rc = os.system.find_directory(be_user_settings, -1, true, dir_path_ptr, 1);
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// const settings_dir = try allocator.dupeZ(u8, mem.sliceTo(dir_path_ptr, 0));
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// defer allocator.free(settings_dir);
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// switch (rc) {
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// 0 => return fs.path.join(allocator, &[_][]const u8{ settings_dir, appname }),
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// else => return error.AppDataDirUnavailable,
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// }
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// },
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else => @compileError("Unsupported OS"),
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}
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}
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test "filePath" {
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const allocator = std.testing.allocator;
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std.testing.log_level = .debug;
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log.debug("\n", .{});
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const path = try filePath(allocator, null, "NOTHING", null, "hello");
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defer allocator.free(path.evaluated_path);
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defer allocator.free(path.home.?);
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try std.testing.expect(path.evaluated_path.len > 10);
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try std.testing.expectEqualStrings("hello", path.evaluated_path[path.evaluated_path.len - 5 ..]);
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try std.testing.expect(path.home != null);
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}
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test "ini to creds" {
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std.testing.log_level = .debug;
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log.debug("\n", .{});
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const partial_creds = try credsForText(
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\\
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\\# Amazon Web Services Credentials File used by AWS CLI, SDKs, and tools
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\\# This file was created by the AWS Toolkit for Visual Studio Code extension.
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\\#
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\\# Your AWS credentials are represented by access keys associated with IAM users.
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\\# For information about how to create and manage AWS access keys for a user, see:
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\\# https://docs.aws.amazon.com/IAM/latest/UserGuide/id_credentials_access-keys.html
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\\#
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\\# This credential file can store multiple access keys by placing each one in a
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\\# named "profile". For information about how to change the access keys in a
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\\# profile or to add a new profile with a different access key, see:
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\\# https://docs.aws.amazon.com/cli/latest/userguide/cli-config-files.html
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\\#
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\\[other_section]
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\\access_key_id = NOTYOURACCESSKEY
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\\
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\\ [default]
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\\ # The access key and secret key pair identify your account and grant access to AWS.
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\\aws_access_key_id = AKIDEXAMPLE # access key
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\\
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\\[another_section]
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\\access_key_id = NOTYOURACCESSKEYEITHER
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, "default");
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try std.testing.expect(partial_creds.access_key != null);
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try std.testing.expectEqualStrings("AKIDEXAMPLE", partial_creds.access_key.?);
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try std.testing.expect(partial_creds.secret_key == null);
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}
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