## Summary of changes

Adds support for the tracer on alpine on ARM64

## Reason for change

We currently support x64 on glibc/alpine but only glibc on arm64. This
closes that matrix which makes it easier to understand

## Implementation details

There's several layers, but at a high level
- Anywhere where we detect platform, make sure to include
`linux-musl-arm64` as well as `linux-arm64`
- Build the tracer + profiler on alpine arm64

There were several difficulties
- The ruby-based fpm bundler we use doesn't work on alpine arm64, hence
#5905
- I couldn't get our existing alpine.build.dockerfile to compile on
arm64 (where we currently compile llvm/clang16 on alpine14).
- To work around it, created a separate alpine.build.arm64.dockerfile
image which uses alpine:18 (the first version that includes clang16) as
the base.
- Obviously this gives us different requirements in arm64, but I think
that's fine because a) this is a new feature b) we already have
differences on the glibc requirements for arm64 c) We only support .NET
5+ anyway on arm64 (.NET 6 really given .NET 5 is mostly gone) and they
ship alpine:18 images for .NET 6+
- I created a multi arch base image from the two base images ([as some
bloke with a blog describes
here](https://andrewlock.net/combining-multiple-docker-images-into-a-multi-arch-image/))
- I had difficulty compiling the profiler on arm64 initially (we require
it for some crash tracking functionality), as we were getting `undefined
reference to `_Uaarch64_get_accessors_int'` when trying to compile
libunwind. @gleocadie tracked it down to [this
issue](libunwind/libunwind#788), and fixed it
by just not building the libunwind tests 🙇‍♂️
- The sqlite IAST instrumentation tests on alpine arm64 were failing in
.NET 5. I _think_ that's because the sqlite package we're using there
doesn't support it (which makes sense) so just disabled the tests for
that scenario. They pass in .NET 6+ so I'm not worried about it.
- Removed the "noop" smoke tests stage (there's nothing to run in it
currently)
- We can't even install .NET Core 2.1 using the dotnet install script on
alpine arm64, so bailing out. We can probably bail out of more too, but
that's not _necessary_ so haven't done it yet.

There's still one outstanding issue I can't get my head around, on
_debian x64_ (i.e. not something that should have changed) The
`OnEolFrameworkInSsi_WhenForwarderPathExists_CallsForwarderWithExpectedTelemetry`
tests is failing by crashing. It's bizarre, I can't figure it out, if
anyone has any ideas, please let me know 😅

## Test coverage

I've run full installer + full TFM tests
[here](https://dev.azure.com/datadoghq/dd-trace-dotnet/_build/results?buildId=162869&view=results)
🤞

## Other details

Stacked on 
- #5770
- #5905

as they both change key parts of the build + will mean we need to
rebuild the VMs

Fixes #3850

---------

Co-authored-by: Gregory LEOCADIE <[email protected]>

## Summary of changes

Replaces the ruby tool `fpm` with `nfpm` and `tar`

## Reason for change

`fpm` is a ruby tool, which means we have to install ruby. This has
historically caused a bunch of issues at various points when
dependencies change (e.g. we add/update anything or change dockerfiles).

[`nfpm` is a go tool](https://github.com/goreleaser/nfpm) created
specifically to do pretty much the same thing as `fpm`, but without
requiring ruby. The only slightly annoying thing is that it doesn't
support raw "tar" so we have to use the built-in `tar` for that
(although that's not a big hardship).

## Implementation details

- Install `nfpm` in the docker images and remove the `fpm` install (and
removing all the other ruby-related code)
- Call `tar` to pack the `tar` images, and `nfpm` to pack the `deb/rpm`
packages
- `nfpm` is a "config" based tool, so we dump the yaml config to a file,
and pass that to the execution
- I have validated the nfpm and fpm deb output are essentially
identical, there are just a few nuances
- `fpm` adds a `License` field to the `.deb` header, but that's non
standard. [The correct
approach](https://www.debian.org/doc/debian-policy/ch-docs.html#copyright-information)
is to include a specific license file. See [this
issue](goreleaser/nfpm#847) for more details.
- Similarly, `fpm` adds a `Vendor` field that is non standard (but
`Maintainer` is standard and is added).
- `fpm` adds `Relocations: /var/datadog` to the `.rpm` header, so I have
replicated that for nfpm, but I don't know that we actually _want_
that... If we let people relocate the headers, then the documentation is
wrong for the profiler env vars etc. Left it as-is anyway, to reduce
chance of breaking people, just something I spotted.
- The `"Apache License 2.0"` license string used for `.rpm` previously
is not a valid value, as defined by fedora, so switched it to the
supported moniker
[here](https://docs.fedoraproject.org/en-US/legal/allowed-licenses/).
- The `tar` files were "accidentally" including the before/after
scripts, so I've made sure to still include them, incase anyone was
relying on those (they run the `createLogPath.sh` file, and create a
symlink to dd-dotnet in `/usr/bin`)

## Test coverage

[Ran a full test with all installers
here](https://dev.azure.com/datadoghq/dd-trace-dotnet/_build/results?buildId=162539&view=results)
- ignore the couple of failures in the dotnet tool smoke tests, those
are failures on `master` I need to fix 😅

Will manually compare the output of this run too:
- [x] tar (`tar -tzvf *.tar.gz`)
- The same, except the before/after scripts weren't being made
executable. Fixed
- [x] deb (`dpkg --info *.deb` and `dpkg -c *.deb`)
  - Minor differences: 
    - nfpm adds the directories as entries
    - nfpm doesn't have the non-standard License field (unlike fpm)
    - nfpm adds the license in the required copyright path
    - nfpm doesn't include a dummy changelog.gz file (unlike fpm)
- [x] rpm (`rpm -qipl --scripts *.rpm`)
- Minor differences, nfpm adds the directories as entries, nothing
significant though

## Other details

Stacked on
- #5770

because we need to change the dockerfiles, and we need the Centos7 fixes
in there at the very least. We'll need to update the VMSS images though
after making these changes so I've been delaying until that makes sense
up to this point.

## Summary of changes

The `release/2.x` branch is broken since I updated the VMs

## Reason for change

I updated VMs yesterday, which cleared the build cache. I knew that
would slow down release/2.x builds but I forgot it would completely
break them due to the centos7 mess.

## Implementation details

Backported some PRs to fix the layer caching etc

- #5770
- #5905
- #5933 (just the changes
in the alpine dockerfile)

## Test coverage

This is the test, hopefully it works 🤞