Develop locally

Hyperdrive can be used when developing and testing your Workers locally by connecting to any local database instance running on your machine directly. Local development uses Wrangler, the command-line interface for Workers, to manage local development sessions and state.

​​ Configure local development

To specify a database to connect to when developing locally, you can:

• Recommended Create a WRANGLER_HYPERDRIVE_LOCAL_CONNECTION_STRING_<BINDING_NAME> environmental variable with the connection string of your database. <BINDING_NAME> is the name of the binding assigned to your Hyperdrive in your wrangler.toml or Pages configuration. This allows you to avoid committing potentially sensitive credentials to source control in your wrangler.toml, if your test/development database is not ephemeral. If you have configured multiple Hyperdrive bindings, replace <BINDING_NAME> with the unique binding name for each.
• Set localConnectionString in wrangler.toml.

If both the WRANGLER_HYPERDRIVE_LOCAL_CONNECTION_STRING_<BINDING_NAME> environmental variable and localConnectionString in wrangler.toml are set, wrangler dev will use the environmental variable instead. Use unset WRANGLER_HYPERDRIVE_LOCAL_CONNECTION_STRING_<BINDING_NAME> to unset any existing environmental variables.

For example, to use the environmental variable, export the environmental variable before running wrangler dev:

# Your configured Hyperdrive binding is "TEST_DB" 
$ export WRANGLER_HYPERDRIVE_LOCAL_CONNECTION_STRING_TEST_DB="postgres://user:password@localhost:5432/databasename"
# Start a local development session referencing this local instance
$ npx wrangler dev

To configure a localConnectionString in wrangler.toml, ensure your Hyperdrive bindings have a localConnectionString property set:

[[hyperdrive]]
binding = "TEST_DB"
id = "c020574a-5623-407b-be0c-cd192bab9545"
localConnectionString = "postgres://user:password@localhost:5432/databasename"

​​ Use wrangler dev

The following example shows you how to check your wrangler version, set a WRANGLER_HYPERDRIVE_LOCAL_CONNECTION_STRING_TEST_DB environmental variable, and run a wrangler dev session:

# Confirm you are using wrangler v3.0+
$ npx wrangler --version
⛅️ wrangler 3.27.0

# Set your environmental variable: your configured Hyperdrive binding is "TEST_DB".
export WRANGLER_HYPERDRIVE_LOCAL_CONNECTION_STRING_TEST_DB="postgres://user:password@localhost:5432/databasename"

# Start a local dev session:
$ npx wrangler dev

# Outputs:
------------------
Found a non-empty WRANGLER_HYPERDRIVE_LOCAL_CONNECTION_STRING_TEST_DB variable. Hyperdrive will connect to this database
during local development.

wrangler dev now uses local mode by default, powered by 🔥 Miniflare and 👷 workerd.
To run an edge preview session for your Worker, use wrangler dev --remote
Your worker has access to the following bindings:
- Hyperdrive configs:
  - TEST_DB: c020574a-5623-407b-be0c-cd192bab9545
⎔ Starting local server...

[mf:inf] Ready on http://127.0.0.1:8787/
[b] open a browser, [d] open Devtools, [l] turn off local mode, [c] clear console, [x] to exit

wrangler dev separates local and production (remote) data. A local session does not have access to your production data by default. To access your production (remote) Hyperdrive configuration, pass the --remote flag when calling wrangler dev. Any changes you make when running in --remote mode cannot be undone.

Refer to the wrangler dev documentation to learn more about how to configure a local development session.

​​ Related resources

• Use wrangler dev to run your Worker and Hyperdrive locally and debug issues before deploying.
• Learn how Hyperdrive works.
• Understand how to configure query caching in Hyperdrive.