Environment variables are a common way to configure various buildpacks at build-time.
Below are a few ways you can do so. All of them will use our samples repo for simplicity.
--env
)The --env
parameter must be one of the following:
VARIABLE=VALUE
VARIABLE
, where the value of VARIABLE
will be taken from the local environmentexport FOO=BAR
pack build sample-app \
--env "HELLO=WORLD" \
--env "FOO" \
--builder cnbs/sample-builder:jammy \
--buildpack samples/buildpacks/hello-world/ \
--buildpack samples/apps/bash-script/bash-script-buildpack/ \
--path samples/apps/bash-script/
docker run sample-app
The following environment variables were set and available to buildpacks at build-time:
Name | Value | Source |
---|---|---|
HELLO |
WORLD |
hard-coded inline value |
FOO |
BAR |
current environment |
--env-file
)The --env-file
parameter must be a path to a file where each line is one of the following:
VARIABLE=VALUE
VARIABLE
, where the value of VARIABLE
will be taken from the current environmentexport FOO=BAR
echo -en "HELLO=WORLD\nFOO" > ./envfile
pack build sample-app \
--env-file ./envfile \
--builder cnbs/sample-builder:jammy \
--buildpack samples/buildpacks/hello-world/ \
--buildpack samples/apps/bash-script/bash-script-buildpack/ \
--path samples/apps/bash-script/
docker run sample-app
The following environment variables were set and available to buildpacks at build-time:
Name | Value | Source |
---|---|---|
HELLO |
WORLD |
hard-coded value in file |
FOO |
BAR |
current environment |
NOTE: Variables defined using
--env
take precedence over variables defined in--env-file
.
The --descriptor
parameter must be a path to a file which follows the project.toml schema.
Without the --descriptor
flag, pack build
will use the project.toml
file in the application directory if it exists.
You can define environment variables in an env
table in the file, and pass those into the application.
cat >> samples/apps/bash-script/project.toml <<EOL
[[build.env]]
name="HELLO"
value="WORLD"
EOL
pack build sample-app \
--builder cnbs/sample-builder:jammy \
--buildpack samples/buildpacks/hello-world/ \
--buildpack samples/apps/bash-script/bash-script-buildpack/ \
--path samples/apps/bash-script/
docker run sample-app
The following environment variables were set and available to buildpacks at build-time:
Name | Value | Source |
---|---|---|
HELLO |
WORLD |
hard-coded value in file |
NOTE: Variables defined using
--env
or--env-file
take precedence over variables defined in theproject.toml
.
NOTE:
project.toml
can’t detect environment variables (so, for instance, if one ranexport FOO=BAR
and addedname=FOO
to theproject.toml
, it wouldn’t detect any value set forFOO
).