Connecting to Cloud SQL (MySQL) from a Go web app

This repo contains the Go source code for a simple web app that can be deployed to App Engine Standard. It is a demonstration of how to connect to a MySQL instance in Cloud SQL. The application is the "Tabs vs Spaces" web app used in the Building Stateful Applications With Kubernetes and Cloud SQL session at Cloud Next '19.

Before you begin

1. If you haven't already, set up a Go Development Environment by following the Go setup guide and create a project.

2. Create a 2nd Gen Cloud SQL Instance by following these instructions. Note the connection string, database user, and database password that you create.

3. Create a database for your application by following these instructions. Note the database name.

4. Create a service account with the 'Cloud SQL Client' permissions by following these instructions. Download a JSON key to use to authenticate your connection.

Running locally

To run this application locally, download and install the cloud_sql_proxy by following the instructions here.

Instructions are provided below for using the proxy with a TCP connection or a Unix Domain Socket. On Linux or Mac OS you can use either option, but on Windows the proxy currently requires a TCP connection.

Launch proxy with TCP

To run the sample locally with a TCP connection, set environment variables and launch the proxy as shown below.

Linux / Mac OS

Use these terminal commands to initialize environment variables:

export GOOGLE_APPLICATION_CREDENTIALS=/path/to/service/account/key.json
export DB_TCP_HOST='127.0.0.1:3306'
export DB_USER='<DB_USER_NAME>'
export DB_PASS='<DB_PASSWORD>'
export DB_NAME='<DB_NAME>'

Then use this command to launch the proxy in the background:

./cloud_sql_proxy -instances=<project-id>:<region>:<instance-name>=tcp:3306 -credential_file=$GOOGLE_APPLICATION_CREDENTIALS &

Windows/PowerShell

Use these PowerShell commands to initialize environment variables:

$env:GOOGLE_APPLICATION_CREDENTIALS="<CREDENTIALS_JSON_FILE>"
$env:DB_TCP_HOST="127.0.0.1:3306"
$env:DB_USER="<DB_USER_NAME>"
$env:DB_PASS="<DB_PASSWORD>"
$env:DB_NAME="<DB_NAME>"

Then use this command to launch the proxy in a separate PowerShell session:

Start-Process -filepath "C:\<path to proxy exe>" -ArgumentList "-instances=<project-id>:<region>:<instance-name>=tcp:3306 -credential_file=<CREDENTIALS_JSON_FILE>"

Launch proxy with Unix Domain Socket

NOTE: this option is currently only supported on Linux and Mac OS. Windows users should use the Launch proxy with TCP option.

To use a Unix socket, you'll need to create the /cloudsql directory and give write access to the user running the proxy. Use these commands to create the directory and set permissions:

sudo mkdir /cloudsql
sudo chown -R $USER /cloudsql

Use these terminal commands to initialize environment variables:

export GOOGLE_APPLICATION_CREDENTIALS=/path/to/service/account/key.json
export INSTANCE_CONNECTION_NAME='<MY-PROJECT>:<INSTANCE-REGION>:<INSTANCE-NAME>'
export DB_USER='<DB_USER_NAME>'
export DB_PASS='<DB_PASSWORD>'
export DB_NAME='<DB_NAME>'

Then use this command to launch the proxy in the background:

./cloud_sql_proxy -dir=/cloudsql --instances=$INSTANCE_CONNECTION_NAME --credential_file=$GOOGLE_APPLICATION_CREDENTIALS &

Testing the application

To test the application locally, follow these steps after the proxy is running:

• Install dependencies: go get ./...
• Run the application: go run cloudsql.go
• Navigate to http://127.0.0.1:8080 in a web browser to verify your application is running correctly.

Deploying to App Engine Standard

To run the sample on GAE-Standard, create an App Engine project by following the setup for these instructions.

First, create an app.yaml with the correct values to pass the environment variables into the runtime. Your app.yaml file should look like this:

runtime: go111
env_variables:
  INSTANCE_CONNECTION_NAME: <project-id>:<region>:<instance-name>
  DB_USER: YOUR_DB_USER
  DB_PASS: YOUR_DB_PASS
  DB_NAME: YOUR_DB

Note: Saving credentials in environment variables is convenient, but not secure - consider a more secure solution such as Cloud KMS to help keep secrets safe.

Next, the following command will deploy the application to your Google Cloud project:

gcloud app deploy

Deploy to Google App Engine Flexible

First, update app.flexible.yaml with the correct values to pass the environment variables into the runtime.

Next, the following command will deploy the application to your Google Cloud project:

gcloud app deploy app.flexible.yaml

To launch your browser and view the app at https://[YOUR_PROJECT_ID].appspot.com, run the following command:

gcloud app browse

Deploy to Cloud Run

See the Cloud Run documentation for more details on connecting a Cloud Run service to Cloud SQL.

1. Build the container image:

gcloud builds submit --tag gcr.io/[YOUR_PROJECT_ID]/run-sql

2. Deploy the service to Cloud Run:

gcloud run deploy run-sql --image gcr.io/[YOUR_PROJECT_ID]/run-sql

Take note of the URL output at the end of the deployment process.

3. Configure the service for use with Cloud Run

gcloud beta run services update run-sql \
    --add-cloudsql-instances [INSTANCE_CONNECTION_NAME] \
    --update-env-vars INSTANCE_CONNECTION_NAME=[INSTANCE_CONNECTION_NAME] \
    --update-env-vars DB_USER=[YOUR_DB_USER] \
    --update-env-vars DB_PASS=[YOUR_DB_PASS] \
    --update-env-vars DB_NAME=[YOUR_DB]

Replace environment variables with the correct values for your Cloud SQL instance configuration.

This step can be done as part of deployment but is separated for clarity.

4. Navigate your browser to the URL noted in step 2.

For more details about using Cloud Run see http://cloud.run. Review other Go on Cloud Run samples.