fix(server): keep ${VAR} self-references interpolatable in .env files

Only escape $ signs that are not part of a well-formed ${VAR} reference
when writing .env files, so Docker Compose's own variable interpolation
still works for legitimate ASSET_URL=${APP_URL}-style references, while
literal dollar signs (e.g. in passwords) stay escaped.

Fixes #5151

apps/dokploy/__test__/compose/env-file-literals.test.ts

@@ -93,4 +93,37 @@ describe("getCreateEnvFileCommand", () => {
 			expect(actual[key], key).toBe(value);
 		}
 	}, 60000);
+
+	it("still interpolates a ${VAR} self-reference in the .env file", () => {
+		mkdirSync(codePath, { recursive: true });
+
+		const serviceEnv = [
+			"APP_URL=https://example.com",
+			'ASSET_URL="${APP_URL}"',
+		].join("\n");
+
+		const command = getCreateEnvFileCommand({
+			appName,
+			composePath: "docker-compose.yml",
+			env: serviceEnv,
+			randomize: false,
+			suffix: "",
+			serverId: null,
+			environment: { project: { env: "" }, env: "" },
+		} as Parameters<typeof getCreateEnvFileCommand>[0]);
+
+		execFileSync("bash", ["-c", command]);
+
+		const composeFile =
+			"services:\n  test:\n    image: busybox\n    environment:\n      - ASSET_URL=${ASSET_URL}\n";
+		writeFileSync(join(codePath, "docker-compose.yml"), composeFile);
+
+		const out = execFileSync(
+			"docker",
+			["compose", "run", "--rm", "-T", "test", "sh", "-c", "printf '%s' \"$ASSET_URL\""],
+			{ cwd: codePath, encoding: "utf8" },
+		);
+
+		expect(out).toBe("https://example.com");
+	}, 60000);
 });

apps/dokploy/__test__/env/environment.test.ts

@@ -1,5 +1,6 @@
 import {
 	prepareEnvironmentVariables,
+	prepareEnvironmentVariablesForFile,
 	prepareEnvironmentVariablesForShell,
 } from "@dokploy/server/index";
 import { describe, expect, it } from "vitest";
@@ -642,3 +643,53 @@ SPECIAL=café résumé naïve
 		expect(resolved[2]).toContain("café");
 	});
 });
+
+describe("prepareEnvironmentVariablesForFile (.env file escaping)", () => {
+	it("keeps a well-formed ${VAR} self-reference interpolatable", () => {
+		const serviceEnv = `
+APP_URL=https://example.com
+ASSET_URL=\${APP_URL}
+`;
+
+		const resolved = prepareEnvironmentVariablesForFile(serviceEnv, "", "");
+
+		expect(resolved).toEqual([
+			`APP_URL="https://example.com"`,
+			`ASSET_URL="\${APP_URL}"`,
+		]);
+	});
+
+	it("keeps a ${VAR:-default} self-reference with a modifier interpolatable", () => {
+		const serviceEnv = `ASSET_URL=\${APP_URL:-https://default.com}`;
+
+		const resolved = prepareEnvironmentVariablesForFile(serviceEnv, "", "");
+
+		expect(resolved).toEqual([`ASSET_URL="\${APP_URL:-https://default.com}"`]);
+	});
+
+	it("escapes a literal dollar sign followed by a word so it isn't interpolated", () => {
+		const serviceEnv = "PASSWORD=pa$word";
+
+		const resolved = prepareEnvironmentVariablesForFile(serviceEnv, "", "");
+
+		expect(resolved).toEqual([`PASSWORD="pa\\$word"`]);
+	});
+
+	it("escapes a trailing dollar sign", () => {
+		const serviceEnv = "PRICE=100$";
+
+		const resolved = prepareEnvironmentVariablesForFile(serviceEnv, "", "");
+
+		expect(resolved).toEqual([`PRICE="100\\$"`]);
+	});
+
+	it("still escapes double quotes and backslashes", () => {
+		const serviceEnv = String.raw`MESSAGE=say "hi" and \backslash`;
+
+		const resolved = prepareEnvironmentVariablesForFile(serviceEnv, "", "");
+
+		expect(resolved).toEqual([
+			String.raw`MESSAGE="say \"hi\" and \\backslash"`,
+		]);
+	});
+});

packages/server/src/utils/docker/utils.ts

@@ -548,7 +548,10 @@ export const prepareEnvironmentVariablesForFile = (
 		const escapedValue = value
 			.replace(/\\/g, "\\\\")
 			.replace(/"/g, '\\"')
-			.replace(/\$/g, "\\$");
+			.replace(
+				/\$(?!\{[A-Za-z_][A-Za-z0-9_]*(?::?[-+?][^}]*)?\})/g,
+				"\\$",
+			);
 		return `${key}="${escapedValue}"`;
 	});
 };