45 lines
1.2 KiB
Markdown
45 lines
1.2 KiB
Markdown
+++
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title = "Shared environment variables for make, bash and docker"
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date = 2020-01-07
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+++
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It is possible to define a set of variables and share them in Make, Bash and the Docker containers that are orchestrated by `docker-compose`.
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Docker-compose can use an `.env` file to substitute variables in a `docker-compose.yml` file in the same directory. In this docker-compose.yml they can be exported to the containers.
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Incuding this `.env` file in your `Makefile` makes hem available there as well, but they are not automatically exported to the Bash shells that are spawned by `make` to execute the targets. This can be changed by adding the `.EXPORTALLVARIABLES:` target to your `Makefile`.
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```
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# .env
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VAR1=this
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VAR2=that
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VAR3=those
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```
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```make
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# Makefile
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include .env
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.EXPORT_ALL_VARIABLES:
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task:
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@echo "VAR1 is ${VAR1}"
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@some_command # some_command can use $VAR1, $VAR2 and $VAR3
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@docker-compose up
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```
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```
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# docker-compose.yml
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...
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app:
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image: "registry/the_app:${VAR2}"
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environment:
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- VAR3=${VAR3}
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```
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## Sources
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- [vsupalov.com](https://vsupalov.com/docker-arg-env-variable-guide/#the-dot-env-file-env)
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- [www.gnu.org](https://www.gnu.org/software/make/manual/html_node/Special-Targets.html#Special-Targets)
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