feat(library): Introduce WAMR

Introduce WAMR (Wasm Micro Runtime) native application for Unikraft. The
version used is an older commit (pre-stable release): `bc762f`.

Add required files: `Kraftfile`, `Makefile.uk` and `README.md`.

The root filesystem (in `rootfs/`) provides the pre-built `main.wasm`
file, passed to as the `cmd` in `Kraftfile`.

Signed-off-by: Razvan Deaconescu <razvand@unikraft.io>

Author: razvand

.github/workflows/library-wamrbc762f.yaml

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+name: library/wamrbc76sf
+
+on:
+  schedule:
+  - cron: '0 0 * * *' # Everyday at 12AM
+
+  push:
+    branches: [main]
+    paths:
+    - 'library/wamr/bc762f/**'
+    - '.github/workflows/library-wamrbc762f.yaml'
+
+  pull_request:
+    types: [opened, synchronize, reopened]
+    branches: [main]
+    paths:
+    - 'library/wamr/bc762f/**'
+    - '.github/workflows/library-wamrbc762f.yaml'
+
+jobs:
+  build:
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+        - plat: qemu
+          arch: x86_64
+        - plat: qemu
+          arch: arm64
+        - plat: fc
+          arch: x86_64
+        - plat: fc
+          arch: arm64
+
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v3
+
+    - name: Build WAMR-bc762f
+      uses: unikraft/kraftkit@staging
+      with:
+        loglevel: debug
+        workdir: library/wamr/bc762f
+        runtimedir: /github/workspace/.kraftkit
+        plat: ${{ matrix.plat }}
+        arch: ${{ matrix.arch }}
+        push: false
+        output: oci://index.unikraft.io/unikraft.org/wamr:bc762f
+
+    - name: Archive OCI digests
+      uses: actions/upload-artifact@v3
+      with:
+        name: oci-digests-${{ matrix.arch }}-${{ matrix.plat }}
+        path: ${{ github.workspace }}/.kraftkit/oci/digests
+        if-no-files-found: error
+
+  push:
+    if: ${{ github.event_name == 'push' || github.event_name == 'schedule' }}
+    needs: [ build ]
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v3
+
+    - name: Login to OCI registry
+      uses: docker/login-action@v2
+      with:
+        registry: index.unikraft.io
+        username: ${{ secrets.REG_USERNAME }}
+        password: ${{ secrets.REG_TOKEN }}
+
+    - name: Retrieve, merge and push OCI digests
+      uses: ./.github/actions/merge-oci-digests
+      with:
+        name: index.unikraft.io/unikraft.org/wamr:bc762f
+        push: true

library/wamr/bc762f/Kraftfile

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+spec: v0.6
+
+name: wamr
+
+rootfs: ./rootfs
+
+cmd: ["/main.wasm"]
+
+unikraft:
+  version: stable
+  kconfig:
+    CONFIG_LIBRAMFS: 'y'
+    CONFIG_LIBUK9P: 'y'
+    CONFIG_LIBUKBUS: 'y'
+    CONFIG_LIBUKCPIO: 'y'
+    CONFIG_LIBUKDEBUG_ANSI_COLOR: 'y'
+    CONFIG_LIBUKLIBPARAM: 'y'
+    CONFIG_LIBVFSCORE_AUTOMOUNT_ROOTFS: 'y'
+    CONFIG_LIBVFSCORE_FSTAB: 'y'
+    CONFIG_LIBVFSCORE_ROOTFS_INITRD: 'y'
+
+targets:
+- qemu/x86_64
+- qemu/arm64
+- fc/x86_64
+- fc/arm64
+
+libraries:
+  musl: stable
+  lwip: stable
+  wamr: stable

library/wamr/bc762f/README.md

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+# WAMR (Wasm Micro Runtime) Image
+
+This directory contains the [WAMR (Wasm Micro Runtime)](https://github.com/bytecodealliance/wasm-micro-runtime) application running on Unikraft, in binary compatibility mode.
+It implements a "Hello, World!" printing program in web assembly and runs it on Unikraft.
+
+## Run and Use
+
+Use `kraft` to run the image and start a Unikraft instance:
+
+```bash
+kraft run --rm --plat qemu --arch x86_64 unikraft.org/wamr:bc762f
+```
+
+If the `--plat` argument is left out, it defaults to `qemu`.
+If the `--arch` argument is left out, it defaults to your system's CPU architecture.
+
+Once executed, it will print a "Hello, World!" message.
+
+## Inspect and Close
+
+To list information about the Unikraft instance, use:
+
+```bash
+kraft ps
+```
+
+```text
+TODO
+```
+
+The instance name is `TODO`.
+To close the Unikraft instance, close the `kraft` process (e.g., via `Ctrl+c`) or run:
+
+```bash
+kraft rm TODO
+```
+
+## Build and Run Locally
+
+The commands so far used the pre-built WAMR image available in the Unikraft registry.
+
+In oder to to build a local WAMR image, clone this repository and `cd` into this directory.
+Then use `kraft` to build an image locally:
+
+```bash
+kraft build --no-cache --no-update --plat qemu --arch x86_64
+```
+
+Similar to the `kraft run` command, if the `--plat` argument is left out, it defaults to `qemu`.
+If the `--arch` argument is left out, it defaults to your system's CPU architecture.
+
+In order to run the locally built image, use `.` (_dot_, the current directory)  as the final argument to the `kraft run` command:
+
+```bash
+kraft run --rm --plat qemu --arch x86_64 .
+```
+
+Same as above, it will open port `8080` and wait for connections.
+
+## `kraft` and `sudo`
+
+Mixing invocations of `kraft` and `sudo` can lead to unexpected behavior.
+Read more about how to start `kraft` without `sudo` at [https://unikraft.org/sudoless](https://unikraft.org/sudoless).
+
+## Learn More
+
+- [How to run unikernels locally](https://unikraft.org/docs/cli/running)
+- [How to build `Dockerfile` root filesystems with BuildKit](https://unikraft.org/guides/building-dockerfile-images-with-buildkit)