Proxy request signing: transform= on @proxy rules, plugin-registered schemes, aws-sigv4 plugin

.bumpy/aws-sigv4-plugin.md

@@ -0,0 +1,5 @@
+---
+"@varlock/aws-sigv4-plugin": minor
+---
+
+Initial release: adds the aws-sigv4 request-signing scheme to the credential proxy. The agent's AWS SDK signs with placeholder credentials; the proxy re-signs with the real keys, deriving region/service from the request, with optional region/service allowlists.

.bumpy/proxy-request-signing.md

@@ -0,0 +1,5 @@
+---
+varlock: minor
+---
+
+Credential proxy: request signing via transform= on @proxy rules. Generic HMAC (hmac-sha256/hmac-sha512) signs the final outbound request with a signing secret the agent never holds, and http-basic writes Basic auth headers the proxy composes from the real secret (base64 encoding otherwise hides placeholders from substitution). Transform options reference credential items with $ITEM syntax; the references are captured without resolving, so secret values never enter rule data. Plugins can register additional signing schemes (option specs drive validation and placeholder management; the signer runs in the proxy per matching request).

package.json

@@ -78,6 +78,8 @@
   },
   "catalog": {
     "@sindresorhus/is": "^7.2.0",
+    "@smithy/protocol-http": "^5.6.0",
+    "@smithy/signature-v4": "^5.7.0",
     "@types/bun": "^1.3.11",
     "@types/node": "25.3.2",
     "ansis": "^4.2.0",

packages/plugins/aws-sigv4/README.md

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+# @varlock/aws-sigv4-plugin
+
+Adds an `aws-sigv4` request-signing scheme to the [varlock credential proxy](https://varlock.dev/guides/proxy/).
+
+The agent's AWS SDK signs requests normally, using the placeholder credentials varlock injects into its environment. The proxy parses the region and service out of the inbound credential scope, strips the placeholder signature, and re-signs the request with the real keys at the network boundary. The secret access key never enters the agent's environment, and the agent cannot produce a valid signature itself.
+
+```env-spec
+# @plugin(@varlock/aws-sigv4-plugin)
+# ---
+# @proxy(domain="*.amazonaws.com", transform={
+#   scheme="aws-sigv4", keyId=$AWS_ACCESS_KEY_ID,
+#   allowedServices=[bedrock, s3],
+# })
+AWS_SECRET_ACCESS_KEY=somePlugin()
+
+# @sensitive
+AWS_ACCESS_KEY_ID=somePlugin()
+```
+
+Not just AWS: the same scheme brokers credentials for any SigV4-authenticated service, including S3-compatible stores (Cloudflare R2, MinIO, Backblaze B2, DigitalOcean Spaces) and DynamoDB-compatible endpoints. Point the rule's `domain` at the service's endpoint.
+
+See the [plugin docs](https://varlock.dev/plugins/aws-sigv4/) for all options and limitations.

packages/plugins/aws-sigv4/package.json

@@ -0,0 +1,57 @@
+{
+  "name": "@varlock/aws-sigv4-plugin",
+  "description": "Varlock plugin adding AWS SigV4 request re-signing to the credential proxy (the agent signs with placeholder credentials; the proxy re-signs with the real keys)",
+  "version": "0.0.0",
+  "type": "module",
+  "homepage": "https://varlock.dev/plugins/aws-sigv4/",
+  "bugs": "https://github.com/dmno-dev/varlock/issues",
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/dmno-dev/varlock.git",
+    "directory": "packages/plugins/aws-sigv4"
+  },
+  "main": "dist/index.js",
+  "types": "dist/index.d.ts",
+  "exports": {
+    "./plugin": "./dist/plugin.cjs"
+  },
+  "files": ["dist"],
+  "scripts": {
+    "dev": "tsup --watch",
+    "build": "tsup",
+    "test": "vitest",
+    "typecheck": "tsc --noEmit"
+  },
+  "keywords": [
+    "varlock",
+    "plugin",
+    "varlock-plugin",
+    "aws",
+    "sigv4",
+    "signature-v4",
+    "credential-proxy",
+    "request-signing",
+    "env",
+    ".env",
+    "dotenv",
+    "environment variables",
+    "env vars",
+    "config"
+  ],
+  "author": "dmno-dev",
+  "license": "MIT",
+  "engines": {
+    "node": ">=22"
+  },
+  "peerDependencies": {
+    "varlock": "workspace:^"
+  },
+  "devDependencies": {
+    "@smithy/protocol-http": "catalog:",
+    "@smithy/signature-v4": "catalog:",
+    "@types/node": "catalog:",
+    "tsup": "catalog:",
+    "varlock": "workspace:^",
+    "vitest": "catalog:"
+  }
+}