paketo-buildpacks/bellsoft-liberica : using from the local dir

[ildar]

I'm (very) new to buildpacks and having a problem with using a custom buildpack from a local directory.

default buildpack

1st, I can use the default buildpack for building and running a Java application (sample app downloaded from https://start.spring.io/) One little log for it: bp1.log

buildpack from a local directory

Unfortunately I can't get (the same?) bellsoft-liberica work for the same scenario from a local folder. I try it like this (after running scripts/build.sh):

pack -v build demo-app --path . --buildpack ../buildpacks/bellsoft-liberica -e BP_JVM_VERSION=17

and get this error:

[detector] target distro name/version labels not found, reading /etc/os-release file
[detector] ======== Error: paketo-buildpacks/bellsoft-liberica@{{.version}} ========
[detector] fork/exec /cnb/buildpacks/paketo-buildpacks_bellsoft-liberica/{{.version}}/bin/detect: no such file or directory
[detector] ======== Results ========
[detector] err:  paketo-buildpacks/bellsoft-liberica@{{.version}}
[detector] Timer: Detector ran for 5.097592ms and ended at 2025-01-27T13:18:54Z
[detector] ERROR: No buildpack groups passed detection.
[detector] ERROR: failed to detect: buildpack(s) failed with err
ERROR: failed to build: executing lifecycle: failed with status code: 21

The full log bp2.log

playing with detect and build

1. Since it cannot find the detect script, I put the binaries produced by scripts/build.sh into the buildpacks/bellsoft-liberica/bin. Detect fails again.
2. If I replace detect by a stub (with exit 0) then pack build finishes without gradle build
3. stubbing build doesn't help either.

I suspect there is a little thing I simply overlook. Please drop me a hint. Thanks in advance.

[dmikusa]

The trick with Paketo buildpacks is that we write them in Go, so they need compiled before you can run them as a buildpack. We have a tool for doing that, libpak-tools. You can use libpak-tools package compile if you want to build the buildpack into a local directory & point to that directory with pack build -b.

You can also run libpak-tools package bundle which does the same thing but then produces an image in your Docker daemon with the buildpack. You can then pack build -b and set the image like docker.io/paketo-buildpacks/bellsoft-liberica and it'll pull the local image.

Either works.

As an aside, you can do this without libpak-tools, but the tool automates the process so we recommend everyone use the tool.

One last note...

pack -v build demo-app --path . --buildpack ../buildpacks/bellsoft-liberica -e BP_JVM_VERSION=17

When you use the -b or --buildpack argument, you MUST specify the entire set of buildpacks to use. By setting --buildpack ../buildpacks/bellsoft-liberica you're telling pack to use one and only one buildpack, which isn't going to work.

The easiest way to figure out the full set of buildpacks is to pack build without -b and see what detects. Then you can pack build -b .. -b .. -b .. and add all of the buildpacks from the detect output, overriding the ones you want to customize.

Hope that helps!

[ildar]

Daniel, thanks a lot for your detailed answer.

Indeed, I got the bellsoft-liberica compiled with libpak-tools and it produced the folder with necessary buildpack.toml and linux/amd64/bin/* files.

Unfortunately that generated buildpak doesn't work either with the same error:

# pack -v build demo-app --path . --buildpack
../buildpacks/bellsoft-liberica-built/ -e BP_JVM_VERSION=17
...
[detector] Timer: Detector started at 2025-01-30T18:32:11Z
[detector] Checking for match against descriptor: {linux amd64  []}
[detector] target distro name/version labels not found, reading /etc/os-release file
[detector] ======== Error: paketo-buildpacks/bellsoft-liberica@{{.version}} ========
[detector] fork/exec /cnb/buildpacks/paketo-buildpacks_bellsoft-liberica/{{.version}}/bin/detect: no such file or directory
[detector] ======== Results ========
[detector] err:  paketo-buildpacks/bellsoft-liberica@{{.version}}
[detector] Timer: Detector ran for 4.90007ms and ended at 2025-01-30T18:32:11Z
[detector] ERROR: No buildpack groups passed detection.
[detector] ERROR: failed to detect: buildpack(s) failed with err
ERROR: failed to build: executing lifecycle: failed with status code: 21

Full log bp3.log. Plz advise. Thanks in advance.
P.S. Yes, I remember I need to add more buildpacks but that doesn't help.

[dmikusa]

Two things come to mind:

1. The folder structure isn't correct so it's not finding the binary. The multi-arch support could be messing this up.
2. The architecture is wrong and not able to run on your system. This seems unlikely though as it should use Go to cross compile for Linux and your architecture.

For 1., please give me a directory listing of everything in ../buildpacks/bellsoft-liberica-built/

For 2., find the detect file that was built, it should be a symlink to a main binary. Run file main and confirm the file is built for linux amd64, which is what looks to be your architecture.

[ildar]

Nothing seems to be wrong from my sight.

[root@alt-docker01 demo-app]# ls -lR ../buildpacks/bellsoft-liberica-built/
../buildpacks/bellsoft-liberica-built/:
total 28
-rw-r--r-- 1 root root 27691 Jan 30 09:22 buildpack.toml
drwxr-xr-x 4 root root    80 Jan 30 09:22 linux

../buildpacks/bellsoft-liberica-built/linux:
total 0
drwxr-xr-x 3 root root 120 Jan 30 09:22 amd64
drwxr-xr-x 3 root root 120 Jan 30 09:22 arm64

../buildpacks/bellsoft-liberica-built/linux/amd64:
total 48
drwxr-xr-x 2 root root   120 Jan 31 09:30 bin
-rw-r--r-- 1 root root 11360 Jan 30 09:22 LICENSE
-rw-r--r-- 1 root root   493 Jan 30 09:22 NOTICE
-rw-r--r-- 1 root root 28986 Jan 30 09:22 README.md

../buildpacks/bellsoft-liberica-built/linux/amd64/bin:
total 11776
lrwxrwxrwx 1 root root       4 Jan 30 09:22 build -> main
lrwxrwxrwx 1 root root       4 Jan 30 09:22 detect -> main
-rwxr-xr-x 1 root root 4714648 Jan 30 09:22 helper
-rwxr-xr-x 1 root root 7336088 Jan 30 09:22 main

../buildpacks/bellsoft-liberica-built/linux/arm64:
total 48
drwxr-xr-x 2 root root   120 Jan 30 09:22 bin
-rw-r--r-- 1 root root 11360 Jan 30 09:22 LICENSE
-rw-r--r-- 1 root root   493 Jan 30 09:22 NOTICE
-rw-r--r-- 1 root root 28986 Jan 30 09:22 README.md

../buildpacks/bellsoft-liberica-built/linux/arm64/bin:
total 11400
lrwxrwxrwx 1 root root       4 Jan 30 09:22 build -> main
lrwxrwxrwx 1 root root       4 Jan 30 09:22 detect -> main
-rwxr-xr-x 1 root root 4587672 Jan 30 09:22 helper
-rwxr-xr-x 1 root root 7078040 Jan 30 09:22 main

[root@alt-docker01 demo-app]# ../buildpacks/bellsoft-liberica-built/linux/amd64/bin/detect --help
version cannot be parsed
[root@alt-docker01 demo-app]# file -s ../buildpacks/bellsoft-liberica-built/linux/amd64/bin/main 
../buildpacks/bellsoft-liberica-built/linux/amd64/bin/main: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), statically linked, stripped

thank you.

[dmikusa]

Ok, you're spot on. I just forgot to tell you one argument. Add the --target-arch amd64 to libpak-tools bundle compile. That will tell it to build a single-arch version which is suitable for running directly like this. The multi-arch version is not the expected format for running directly, and it defaults to multi-arch.

[ildar]

Daniel, thank you so much. It worked this way.