58 lines
2.0 KiB
Markdown
58 lines
2.0 KiB
Markdown
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---
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description: Declare default environment variables in a file
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keywords: fig, composition, compose, docker, orchestration, environment, env file
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title: Declare default environment variables in file
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---
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Compose supports declaring default environment variables in an environment file
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named `.env` placed in the folder where the `docker-compose` command is executed
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*(current working directory)*.
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## Syntax rules
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These syntax rules apply to the `.env` file:
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* Compose expects each line in an `env` file to be in `VAR=VAL` format.
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* Lines beginning with `#` are processed as comments and ignored.
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* Blank lines are ignored.
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* There is no special handling of quotation marks. This means that
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**they are part of the VAL**.
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## Compose file and CLI variables
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The environment variables you define here are used for
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[variable substitution](compose-file/index.md#variable-substitution)
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in your Compose file, and can also be used to define the following
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[CLI variables](reference/envvars.md):
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- `COMPOSE_API_VERSION`
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- `COMPOSE_CONVERT_WINDOWS_PATHS`
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- `COMPOSE_FILE`
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- `COMPOSE_HTTP_TIMEOUT`
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- `COMPOSE_TLS_VERSION`
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- `COMPOSE_PROJECT_NAME`
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- `DOCKER_CERT_PATH`
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- `DOCKER_HOST`
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- `DOCKER_TLS_VERIFY`
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> **Notes**
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>
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> * Values present in the environment at runtime always override those defined
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> inside the `.env` file. Similarly, values passed via command-line arguments
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> take precedence as well.
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> * Environment variables defined in the `.env` file are not automatically
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> visible inside containers. To set container-applicable environment variables,
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> follow the guidelines in the topic
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> [Environment variables in Compose](environment-variables.md), which
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> describes how to pass shell environment variables through to containers,
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> define environment variables in Compose files, and more.
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## More Compose documentation
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- [User guide](index.md)
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- [Installing Compose](install.md)
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- [Getting Started](gettingstarted.md)
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- [Command line reference](reference/index.md)
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- [Compose file reference](compose-file/index.md)
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- [Sample apps with Compose](samples-for-compose.md)
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