You can provide environment variables to your site to customize its behavior in different environments.
Environment variables can be distinguished between different types.
There are environment variables that are defined in special places intended to be used in different deployment environments. You can call these “Project Env Vars”.
And there are true OS-level environment variables that might be used in command-line calls. You can call these “OS Env Vars”.
In both cases you want to be able to access the relevant value of these variables for the environment you are in.
By default Gatsby supports 2 environments:
- Development. If you run
gatsby develop, then you will be in the ‘development’ environment.
- Production. If you run
gatsby serve, then you will be in the ‘production’ environment.
If you want to define other environments then you’ll need to do a little more work. See “Additional Environments” below. You can also have a look at the environment variables CodeSandbox while reading the examples.
Once the environment variables have been embedded into the client-side code, they are accessible from the
OS Env Vars are accessible in Node.js from the same
process.env global variable.
Note that since these variables are embedded at build time, you will need to restart your dev server or rebuild your site after changing them.
an environment config file,
.env.production, in your root folder.
In addition to these Project Environment Variables defined in
.env.* files, you could also define
OS Env Vars. OS Env Vars which are prefixed with
GATSBY_ will become available in
Gatsby runs several Node.js scripts at build time, notably
OS Env Vars will already be available when Node is running, so you can add environment variables the
typical ways, e.g. by adding environment variables through your hosting/build tool, your OS, or when
calling Gatsby on the command line.
In Linux terminals this can be done with:
In Windows it’s a little more complex. Check out this Stack Overflow article for some options
Project environment variables that you defined in the
.env.* files will NOT be immediately available
in your Node.js scripts. To use those variables, use npm package dotenv to
examine the active
.env.* file and attach those values.
dotenv is already a dependency of Gatsby, so you can require it in your
gatsby-node.js like this:
Now the variables are available on
process.env as usual.
Please note that you shouldn’t commit
.env.* files to your source control and rather use options given by your Continuous Deployment (CD) provider. An example is Netlify with its build environment variables.
Note: since Gatsby uses the webpack DefinePlugin to make the environment variables available at runtime, they cannot be destructured from
process.env; instead, they have to be fully referenced.
GATSBY_API_URL will be available to your site (Client-side and server-side) as
In Node, your site has access to your
API_KEY (Server-side) using the identifier
process.env.API_KEY. To access it client-side, you can use a
.env.* file containing
API_KEY. However, you are strongly advised against checking these files into source control as it’s a security issue to expose the API key. As a more secure alternative, you can prefix your variable with
GATSBY_ (as shown above). With this prefix, Gatsby automatically embeds the variable as
process.env.GATSBY\_\* in compiled JS making it available in the browser context without exposing it elsewhere.
You can not override certain environment variables as some are used internally for optimizations during build, such as:
Gatsby also allows you to specify another environment variable when running the local development server (e.g.
npm run develop):
This allows you to refresh your sourced content. See Refreshing Content.
Gatsby uses additional environment variables in the build step to fine-tune the outcome of a build. You may find these helpful for more advanced configurations, such as using CI/CD to deploy a Gatsby site.
For example, you can set
CI=true as an environment variable to allow Gatsby’s build script to tailor the terminal output to an automated deployment environment. Some CI/CD tooling may already set this environment variable. This is useful for limiting the verbosity of the build output for dumb terminals, such as terminal in progress animations.
Gatsby detects an optimal level of parallelism for the render phase of
gatsby build based on the reported number of physical CPUs. For builds that are run in virtual environments, you may need to adjust the number of worker parallelism with the
GATSBY_CPU_COUNT environment variable. See Multi-core builds.
As noted above
NODE_ENV is a reserved environment variable in Gatsby as it is needed by the build system to make key optimizations when compiling React and other modules. For this reason it is necessary to make use of a secondary environment variable for additional environment support, and manually make the environment variables available to the client-side code.
You can define your own OS Env Var to track the active environment, and then to locate the relevant Project Env Vars to load. Gatsby itself will not do anything with that OS Env Var, but you can use it in
Specifically, you can use
dotenv and your individual OS Env Var to locate the
.env.myCustomEnvironment file, and then use
If you would like to add a
staging environment with a custom Google Analytics Tracking ID, and a dedicated
apiUrl you can add
.env.staging at the root of your project. In order to do so, use the following modification to your
This will then load the values from the relevant environment’s
.env.* file and make them available via GraphQL queries and the analytics plugin respectively.
Local testing of the
staging environment can be done with: