#env variables not available in builds

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azure harbor
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i added a .env to the root of my project. the site uses it locally in development. but when i build the environment variable isn't found. in a .js file in the project i do const test = import.meta.env.TEST and when i console.log(test) locally i see the value i assigned to TEST in .env but in builds i don't. why and how to fix or be more idiomatic.

quartz lotusBOT
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Hi @azure harbor. I'm kapa.ai, your friendly support bot. I will try to answer your question by searching through the knowledge base. :wave:

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Astro's handling of environment variables during the build process is a bit nuanced. If an .env file containing environment variables is present when the build process is run, these values will be hard-coded in the output, just as when generating a static website. This means that if you have import.meta.env.TEST in your code, it will be replaced with the value of TEST from the .env file during the build process. This is why you're not seeing the expected value in your built application.

To use runtime environment variables, you need to ensure that these variables are absent from the .env file during the build, and provide Astro with every environment variable to expect at run-time. You can do this by running the build command like this: TEST=placeholder astro build. This signals to Astro that the actual value will be available when the built application is run. The placeholder value will be ignored by the build process, and Astro will use the value provided at run-time.

If you have multiple runtime variables, you can store them in a separate file (e.g. .env.runtime) from .env. Start the build with the following command:

export $(cat .env.runtime) && astro build

This will ensure that your environment variables are available at runtime as expected.

For more information, you can refer to the Astro documentation on runtime environment variables (https://docs.astro.build/en/guides/integrations-guide/node#runtime-environment-variables) and using environment variables (https://docs.astro.build/en/guides/environment-variables#getting-environment-variables).

Note: you can ask me a follow up question by @ mentioning me again :speech_balloon:

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@azure harbor kapa.ai is still learning and improving, please let us know how it did by reacting below

azure harbor
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@quartz lotus are you saying that if i have this in my .env file TEST="myval" that when i run the project locally where i have import.meta.env.TEST in my code that will resolve to "myval" but when i build the project (astro build) that the .env file will not get used correctly and that import.meta.env.TEST will resolve to something else?

quartz lotusBOT
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Let me check the knowledge base for you. One moment! :books:

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Yes, that's correct. When you run astro build, the environment variables from your .env file are baked into the built files. This means that import.meta.env.TEST in your code will be replaced with the string "myval" during the build process. This is why you're seeing the value from your .env file when you run the project locally, but not when you build the project.

However, if you want to use runtime environment variables (i.e., variables that are not hard-coded into the built files, but are instead determined at runtime), you need to ensure that these variables are not present in the .env file during the build. Instead, you should provide them when starting your built application.

For example, you could run your built application with the command TEST="myval" astro preview. This will provide the TEST environment variable at runtime, and import.meta.env.TEST in your code will resolve to "myval" as expected.

For more information, you can refer to the Astro documentation on runtime environment variables (https://docs.astro.build/en/guides/integrations-guide/node#runtime-environment-variables) and using environment variables (https://docs.astro.build/en/guides/environment-variables#getting-environment-variables).

Note: you can ask me a follow up question by @ mentioning me again :speech_balloon:

#

@azure harbor kapa.ai is still learning and improving, please let us know how it did by reacting below

azure harbor
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@quartz lotus i am confused when you say, "This is why you're seeing the value from your .env file when you run the project locally, but not when you build the project." i feel like i am doing it correctly. i have a variable and a value in that file like TEST="myval" and in a javascript file i am using it like import.meta.env.TEST which resolves to "myval" in development but does not get replaced with "myval" when i run astro build. it appears i am doing everything correctly and not getting the result you are claiming i should get.

quartz lotusBOT
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Let me check the knowledge base for you. One moment! :books:

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I apologize for the confusion. Let's clarify this.

When you run astro dev, Astro uses Vite under the hood, which loads your .env file and makes those variables available in your application through import.meta.env. So, import.meta.env.TEST will correctly resolve to "myval" in development mode.

However, when you run astro build, the behavior is a bit different. If TEST is defined in your .env file when you run astro build, the value of TEST from the .env file is baked into the built files. This means that import.meta.env.TEST in your code is replaced with the string "myval" during the build process.

But, if you're seeing that import.meta.env.TEST is not replaced with "myval" in the built files, it could be due to a couple of reasons:

  1. There might be a bug in Astro that's causing this behavior. There have been issues reported (https://github.com/withastro/astro/issues/7195) about environment variables not being accessible in the built code.

  2. The environment variable might be getting overwritten somewhere else in your code or build process.

To debug this, you could try the following:

  • Check if the environment variable is being overwritten somewhere else in your code or build process.
  • Try building the project without the .env file and provide the TEST environment variable at build time, like this: TEST="myval" astro build. This should replace import.meta.env.TEST with "myval" in the built files.
  • If none of the above works, consider opening an issue in the Astro GitHub repository (https://github.com/withastro/astro/issues) to report this behavior.
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I hope this helps clarify the behavior of environment variables in Astro. If you have any more questions, feel free to ask!

Note: you can ask me a follow up question by @ mentioning me again :speech_balloon:

#

@azure harbor kapa.ai is still learning and improving, please let us know how it did by reacting below

azure harbor
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@quartz lotus is there some limitation that in builds this kind of code in a .js file simply won't work (even though it does in development)? it appears that in builds the variables in the .env are not getting used and i can't figure out why.
"""
import siteData from "@config/siteData.json.ts";

export function getSite(hostname) {
let front = import.meta.env.FRONT;
console.log({ front, hostname });

if (hostname) {
front = hostname.split(":")[0].split(".")[0];
}

return siteData[front] || siteData["default"];
}
"""

quartz lotusBOT
#

Let me check the knowledge base for you. One moment! :books:

#

Astro's handling of environment variables during the build process is a bit nuanced. If an .env file containing environment variables is present when the build process is run, these values will be hard-coded in the output, just as when generating a static website. This means that if you have import.meta.env.FRONT in your code, it will be replaced with the value of FRONT from the .env file during the build process.

However, if you're seeing that import.meta.env.FRONT is not replaced with the expected value in the built files, it could be due to a couple of reasons:

  1. There might be a bug in Astro that's causing this behavior. There have been issues reported (https://github.com/withastro/astro/issues/7195) about environment variables not being accessible in the built code.

  2. The environment variable might be getting overwritten somewhere else in your code or build process.

To debug this, you could try the following:

  • Check if the environment variable is being overwritten somewhere else in your code or build process.
  • Try building the project without the .env file and provide the FRONT environment variable at build time, like this: FRONT="your_value" astro build. This should replace import.meta.env.FRONT with "your_value" in the built files.
  • If none of the above works, consider opening an issue in the Astro GitHub repository (https://github.com/withastro/astro/issues) to report this behavior.