--volume)The --volume parameter must be one of the following:
Each volume mount has the following format:
<host path>:<target path>[:<mode>]
<host path>This is the name of the volume, it is unique on a given host machine.
<target path>The path where the file or directory is available in the container.
[:<mode>]An optional comma separated list of mount options. If no options are provided, the read-only option will be used. A mount option must be one of the following:
ro, volume contents are read-only.rw, volume contents are readable and writeable.volume-opt=key=value, can be specified more than once, takes a key-value pair consisting of the option name and its value.For the following examples we will use our samples repo for simplicity.
Here we bind mount a local folder into our container and display its contents during
a pack build.
We’ll create a new docker volume:
docker volume create test-volume
Next, we’ll create a text file on the volume:
docker run --rm \
--volume test-volume:/tmp/volume:rw \
bash \
bash -c 'echo "Hello from a volume!" > /tmp/volume/volume_contents.txt'
Now, we can mount this volume during pack build:
ls -al
pack build volume-example \
--builder cnbs/sample-builder:jammy \
--buildpack samples/buildpacks/hello-world \
--path samples/apps/bash-script \
--volume test-volume:/platform/volume:ro
The above pack build ... command will mount the test-volume volume in the /platform directory of the container.
Since we are using the samples/hello-world buildpack, we should see the /platform directory files listed:
[builder] platform_dir files:
...
[builder] /platform/volume:
[builder] total 12
[builder] drwxr-xr-x 2 root root 4096 Sep 17 20:17 .
[builder] drwxr-xr-x 1 root root 4096 Sep 17 20:18 ..
[builder] -rw-r--r-- 1 root root 21 Sep 17 20:18 volume_contents.txt