LocalCloud Cloud SQL Local Emulator
Get started
local.cloud / agents
Read this page as Markdown ↗
local.cloud — Cloud SQL Local Emulator .md Open tab
LocalCloud Google Cloud in-a-box

Cloud SQL

Cloud SQL is a managed relational database service. LocalCloud exposes supported instance, database, and user APIs with local PostgreSQL and MySQL engines for application tests.

When to use Cloud SQL

Typical uses

Use when your application relies on a relational schema, SQL migrations, and transactions through PostgreSQL or MySQL drivers. Test database and user provisioning alongside application queries.

Examples

  • Relational application backends
  • Database provisioning and migration tests

Explore another service

View all

Example usage

Service ID: cloudsql. Starts by default. Use an already running LocalCloud runtime for the examples below.

Export the local project and mapped endpoints in your client process, then use the client settings below. First-time setup 

# Export GOOGLE_CLOUD_PROJECT and CLOUD_SQL_EMULATOR_HOST
eval "$(localcloud env)"

REST gateway examples use the generated HTTP address in SERVICE_USAGE_EMULATOR_HOST; native SDKs can use a different protocol.

Java · REST

List SQL instances

List SQL instances; Cloud SQL provides relational databases for application queries, migrations, and transactions.

Call the Google Cloud REST API with the JDK HTTP client. Requires JDK 17+. Results reflect resources already created in your local project.

Discovery check · reads existing local state.

Save as Hello.java

import java.net.URI;
import java.net.http.*;
import java.time.Duration;
import java.util.Objects;

public class Hello {
  public static void main(String[] args) throws Exception {
    var project = Objects.requireNonNull(System.getenv("GOOGLE_CLOUD_PROJECT"));
    var endpoint = Objects.requireNonNull(System.getenv("SERVICE_USAGE_EMULATOR_HOST"));
    var url = URI.create(endpoint.replaceAll("/+$", "") + "/sql/v1beta4/projects/" + project + "/instances");
    var request = HttpRequest.newBuilder(url).timeout(Duration.ofSeconds(30)).GET().build();
    var client = HttpClient.newBuilder().connectTimeout(Duration.ofSeconds(10)).build();
    var response = client.send(request, HttpResponse.BodyHandlers.ofString());
    if (response.statusCode() >= 400) {
      throw new IllegalStateException(response.statusCode() + ": " + response.body());
    }
    System.out.println(response.body());
  }
}

Run the example

java Hello.java

Verify the result

The request succeeds. An empty list or no printed rows is valid before matching resources exist. Continue with the documented workflows for a resource test.

Verify a resource workflow by creating isolated state, performing the operation, and reading the result back. Run cleanup even after a failure; delete only test-owned resources.

Connection failed? Check localcloud status --verbose, enabled services, and client exports. Stop accidental Google Cloud calls; correct local routing before retrying.

Documented workflows

  • Instance/database/user lifecycle; PostgreSQL and on-demand MySQL 8.4

    Create a local instance, database, and user, then connect through PostgreSQL or on-demand MySQL 8.4. Run a migration and assert rows through the native driver.

  • Backup metadata CRUD and instance administration responses

    Create, list, and delete backup metadata and inspect instance administration responses. Export, import, restore, restart, and replica verbs return DONE without performing those data operations.

  • Local server CA discovery and client certificate issuance

    With LocalCloud-generated TLS enabled, retrieve the engine CA and issue a client certificate, then verify the server through your driver. Operator-provided chains do not give LocalCloud a CA signing key.

Service boundaries

  • Shared engines; version labels, instance flags, and infrastructure settings do not provision separate servers
  • Backups are metadata; export/import/restore/restart and replica verbs do no data work. Replace-restore and migration leave Cloud SQL untouched
  • MySQL requires Docker access; project exports omit MySQL data, non-public PostgreSQL schemas, and passwords
  • requireSsl/sslMode, revocation, and CA rotation are not enforced; PostgreSQL does not require client certificates

Code examples and integrations

Terraform · HCL

Provision resources with Terraform

Documented resources, provider configuration, and local routing setup.

Open guide
Integration

Build an integration test loop

Start the runtime, verify readiness, exercise your SDK, and clean up test state.

Open guide
Agent testing

Use Cloud SQL with an AI agent

Before the agent changes application logic, have it create local Cloud SQL state, read it back with the project SDK, and note which feature the check covered. That first local call catches accidental production routing and needs no GCP account, service-account key, or billing project.

Configure this repo

Set up this repository to use LocalCloud for local GCP development. First read https://local.cloud/ai/agents.md, then inspect this repo, identify the GCP services and SDK language, configure emulator environment variables, and run the narrowest integration test against localhost. Do not use real GCP credentials or production endpoints.

Production endpoints, auth, IAM, quotas, regional behavior, and final release validation still need the target Google Cloud project.

Agent resources has more prompts and the AGENTS.md template.

Related guides

Desktop view