Unable to build UI on non-x86 platforms

[Lee Trager]

While investigating a build failure on PPC64 I noticed that the UI is unable to be built on non-x86 platforms. This is because the UI build scripts always download x86_64 NodeJS. We haven't run into this before because the build manager builds a source tarball which actually builds the UI. Since all of us use x86_64 machine we don't run into it. Like MAAS the UI should be able to be built on any supported architecture.

I was able to produce this by trying to build MAAS on the PPC64 machine in the CI.

$ make package
rm -rf /home/ubuntu/build-area
mkdir -p /home/ubuntu/build-area
make -C src/maasui build
make[1]: Entering directory '/home/ubuntu/maas/src/maasui'
yarn --cwd src build-all
/home/ubuntu/maas/src/maasui/nodejs/bin/yarn: 20: exec: node: Exec format error
make[1]: *** [Makefile:37: src/build] Error 2
make[1]: Leaving directory '/home/ubuntu/maas/src/maasui'
make: *** [Makefile:149: src/maasui/build] Error 2
$ uname -a
Linux PPC64 5.4.0-48-generic #52-Ubuntu SMP Thu Sep 10 11:02:31 UTC 2020 ppc64le ppc64le ppc64le GNU/Linux
$ file /home/ubuntu/maas/src/maasui/nodejs/bin/node
/home/ubuntu/maas/src/maasui/nodejs/bin/node: ELF 64-bit LSB executable, x86-64, version 1 (GNU/Linux), dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2, for GNU/Linux 2.6.32, BuildID[sha1]=55ed8211666f9ccba08369dc9507a3d65fcc09d3, with debug_info, not stripped

[Kit Randel (blr)]

Hey Lee, it looks like there's a tarball provided for PPC LE:

e.g. https://nodejs.org/dist/v12.18.4/node-v12.18.4-linux-ppc64le.tar.xz
https://nodejs.org/en/download/