mirror of https://github.com/docker/docs.git
69 lines
2.6 KiB
Markdown
69 lines
2.6 KiB
Markdown
---
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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 project directory. Docker Compose versions earlier than `1.28`,
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load the `.env` file from the current working directory, where the command is executed, or from the
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project directory if this is explicitly set with the `--project-directory` option. This
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inconsistency has been addressed starting with `+v1.28` by limiting the default `.env` file path
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to the project directory. You can use the `--env-file` commandline option to override the default
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`.env` and specify the path to a custom environment file.
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The project directory is specified by the order of precedence:
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- `--project-directory` flag
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- Folder of the first `--file` flag
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- Current directory
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## Syntax rules
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The following 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/compose-file-v3.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_PROFILES`
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- `COMPOSE_PROJECT_NAME`
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- `COMPOSE_TLS_VERSION`
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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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