feat(library): Introduce Caddy 2.7

Introduce Caddy bincompat run. Build Caddy as static PIE using a
Dockerfile, inspired by Caddy's own Docker setup. Use `xcaddy` to build.
The build uses binary compatibility mode (i.e. the `base` image).

Create a build of the `base` (ELF Loader) and embedded the Caddy files
as an initial ramdisk.

Add:

* `Kraftfile`: Kraft configuration to build and run
* `Dockerfile`: base Caddy filesystem
* `Caddyfile`: Caddy configuration file
* `README.md`: details on building and running Caddy

Signed-off-by: Razvan Deaconescu <[email protected]>

library/caddy/2.7/Caddyfile

@@ -0,0 +1,3 @@
+:2015
+
+respond "Hello, world!"

library/caddy/2.7/Dockerfile

@@ -0,0 +1,37 @@
+# Inspired from: https://github.com/caddyserver/caddy-docker/blob/master/2.7/builder/Dockerfile
+FROM golang:1.21.4-bookworm AS build
+
+RUN set -xe; \
+    apt-get update ; \
+    apt-get install -y --no-install-recommends \
+      ca-certificates \
+      git \
+      libcap2-bin \
+    ;
+
+ENV XCADDY_VERSION 0.3.5
+
+# Configures xcaddy to build with this version of Caddy
+ENV CADDY_VERSION v2.7.5
+
+# Configures xcaddy to not clean up post-build (unnecessary in a container)
+ENV XCADDY_SKIP_CLEANUP 1
+
+# Sets capabilities for output caddy binary to be able to bind to privileged ports
+ENV XCADDY_SETCAP 1
+
+RUN set -xe; \
+    wget -O /tmp/xcaddy.tar.gz "https://github.com/caddyserver/xcaddy/releases/download/v${XCADDY_VERSION}/xcaddy_${XCADDY_VERSION}_linux_amd64.tar.gz"; \
+    tar x -z -f /tmp/xcaddy.tar.gz -C /usr/bin xcaddy; \
+    rm -f /tmp/xcaddy.tar.gz; \
+    chmod +x /usr/bin/xcaddy;
+
+ENV CGO_ENABLED=1
+ENV XCADDY_GO_BUILD_FLAGS "-buildmode=pie -ldflags '-linkmode external -extldflags -static-pie'"
+
+RUN /usr/bin/xcaddy build
+
+FROM scratch
+
+COPY --from=build /go/caddy /usr/local/bin/caddy
+COPY ./Caddyfile /etc/caddy/Caddyfile

library/caddy/2.7/Kraftfile

@@ -0,0 +1,138 @@
+spec: v0.6
+
+name: caddy
+
+rootfs: ./Dockerfile
+
+template:
+  source: https://github.com/unikraft/app-elfloader
+  version: staging
+
+cmd: ["/usr/bin/caddy", "run", "--config", "/etc/caddy/Caddyfile"]
+
+unikraft:
+  source: https://github.com/unikraft/unikraft
+  version: staging
+  kconfig:
+    # Configurations options for app-elfloader
+    # (they can't be part of the template atm)
+    CONFIG_APPELFLOADER_ARCH_PRCTL: 'y'
+    CONFIG_APPELFLOADER_BRK: 'y'
+    CONFIG_APPELFLOADER_CUSTOMAPPNAME: 'y'
+    CONFIG_APPELFLOADER_STACK_NBPAGES: 128
+    CONFIG_APPELFLOADER_VFSEXEC_EXECBIT: 'n'
+    CONFIG_APPELFLOADER_VFSEXEC: 'y'
+    CONFIG_APPELFLOADER_HFS: 'y'
+    CONFIG_APPELFLOADER_HFS_ETCRESOLVCONF: 'y'
+    CONFIG_APPELFLOADER_HFS_ETCHOSTS: 'y'
+    CONFIG_APPELFLOADER_HFS_ETCHOSTNAME: 'y'
+    CONFIG_APPELFLOADER_HFS_REPLACEEXIST: 'y'
+    # Unikraft options
+    CONFIG_HAVE_PAGING_DIRECTMAP: 'y'
+    CONFIG_HAVE_PAGING: 'y'
+    CONFIG_I8042: 'y'
+    CONFIG_LIBDEVFS_AUTOMOUNT: 'y'
+    CONFIG_LIBDEVFS_DEV_NULL: 'y'
+    CONFIG_LIBDEVFS_DEV_STDOUT: 'y'
+    CONFIG_LIBDEVFS_DEV_ZERO: 'y'
+    CONFIG_LIBDEVFS: 'y'
+    CONFIG_LIBPOSIX_ENVIRON_ENVP0: "PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
+    CONFIG_LIBPOSIX_ENVIRON_ENVP1: "LD_LIBRARY_PATH=/usr/local/lib:/usr/lib:/lib"
+    CONFIG_LIBPOSIX_ENVIRON_ENVP2: "HOME=/"
+    CONFIG_LIBPOSIX_ENVIRON: 'y'
+    CONFIG_LIBPOSIX_EVENTFD: 'y'
+    CONFIG_LIBPOSIX_FDIO: 'y'
+    CONFIG_LIBPOSIX_FDTAB: 'y'
+    CONFIG_LIBPOSIX_FUTEX: 'y'
+    CONFIG_LIBPOSIX_MMAP: 'y'
+    CONFIG_LIBPOSIX_NETLINK: 'y'
+    CONFIG_LIBPOSIX_PIPE: 'y'
+    CONFIG_LIBPOSIX_POLL: 'y'
+    CONFIG_LIBPOSIX_PROCESS_CLONE: 'y'
+    CONFIG_LIBPOSIX_SOCKET: 'y'
+    CONFIG_LIBPOSIX_SYSINFO: 'y'
+    CONFIG_LIBPOSIX_TIME: 'y'
+    CONFIG_LIBPOSIX_TIMERFD: 'y'
+    CONFIG_LIBPOSIX_UNIXSOCKET: 'y'
+    CONFIG_LIBPOSIX_USER_GID: 0
+    CONFIG_LIBPOSIX_USER_GROUPNAME: "root"
+    CONFIG_LIBPOSIX_USER_UID: 0
+    CONFIG_LIBPOSIX_USER_USERNAME: "root"
+    CONFIG_LIBPOSIX_USER: 'y'
+    CONFIG_LIBRAMFS: 'y'
+    CONFIG_LIBSYSCALL_SHIM_HANDLER_ULTLS: 'y'
+    CONFIG_LIBSYSCALL_SHIM_HANDLER: 'y'
+    CONFIG_LIBSYSCALL_SHIM_LEGACY_VERBOSE: 'y'
+    CONFIG_LIBSYSCALL_SHIM: 'y'
+    CONFIG_LIBUKALLOCPOOL: 'y'
+    CONFIG_LIBUKBLKDEV_SYNC_IO_BLOCKED_WAITING: 'y'
+    CONFIG_LIBUKBLKDEV: 'y'
+    CONFIG_LIBUKBOOT_BANNER_MINIMAL: 'y'
+    CONFIG_LIBUKBOOT_HEAP_BASE: '0x400000000'
+    CONFIG_LIBUKBOOT_MAINTHREAD: 'y'
+    CONFIG_LIBUKBOOT_SHUTDOWNREQ_HANDLER: 'y'
+    CONFIG_LIBUKCPIO: 'y'
+    CONFIG_LIBUKDEBUG_CRASH_SCREEN: 'y'
+    CONFIG_LIBUKDEBUG_ENABLE_ASSERT: 'y'
+    CONFIG_LIBUKDEBUG_PRINT_SRCNAME: 'n'
+    CONFIG_LIBUKDEBUG_PRINT_TIME: 'y'
+    CONFIG_LIBUKDEBUG_PRINTK_ERR: 'y'
+    CONFIG_LIBUKDEBUG_PRINTK: 'y'
+    CONFIG_LIBUKDEBUG: 'y'
+    CONFIG_LIBUKFALLOC: 'y'
+    CONFIG_LIBUKMPI: 'n'
+    CONFIG_LIBUKSIGNAL: 'y'
+    CONFIG_LIBUKSWRAND_DEVFS: 'y'
+    CONFIG_LIBUKSWRAND: 'y'
+    CONFIG_LIBUKVMEM_DEFAULT_BASE: '0x0000001000000000'
+    CONFIG_LIBUKVMEM_DEMAND_PAGE_IN_SIZE: 12
+    CONFIG_LIBUKVMEM_PAGEFAULT_HANDLER_PRIO: 4
+    CONFIG_LIBUKVMEM: 'y'
+    CONFIG_LIBVFSCORE_AUTOMOUNT_ROOTFS: 'y'
+    CONFIG_LIBVFSCORE_FSTAB: 'y'
+    CONFIG_LIBVFSCORE_NONLARGEFILE: 'y'
+    CONFIG_LIBVFSCORE_ROOTFS_EINITRD: 'y'
+    CONFIG_LIBVFSCORE: 'y'
+    CONFIG_OPTIMIZE_DEADELIM: 'y'
+    CONFIG_OPTIMIZE_LTO: 'y'
+    CONFIG_PAGING: 'y'
+    CONFIG_STACK_SIZE_PAGE_ORDER: 4 # 128 * 4K = 512K
+    CONFIG_UKPLAT_KSP_SIZE: 32768
+    CONFIG_UKPLAT_MEMREGION_MAX_COUNT: 64
+
+    # Debug options
+    # CONFIG_LIBUKDEBUG_PRINTD: 'y'
+    # CONFIG_LIBUKDEBUG_PRINTK_INFO: 'y'
+    CONFIG_LIBSYSCALL_SHIM_STRACE: 'y'
+    # CONFIG_LIBSYSCALL_SHIM_DEBUG: 'y'
+
+libraries:
+  lwip:
+    source: https://github.com/unikraft/lib-lwip
+    version: staging
+    kconfig:
+      CONFIG_LWIP_LOOPIF: 'y'
+      CONFIG_LWIP_UKNETDEV: 'y'
+      CONFIG_LWIP_LOOPBACK: 'y'
+      CONFIG_LWIP_TCP: 'y'
+      CONFIG_LWIP_UDP: 'y'
+      CONFIG_LWIP_RAW: 'y'
+      CONFIG_LWIP_WND_SCALE: 'y'
+      CONFIG_LWIP_TCP_KEEPALIVE: 'y'
+      CONFIG_LWIP_THREADS: 'y'
+      CONFIG_LWIP_HEAP: 'y'
+      CONFIG_LWIP_SOCKET: 'y'
+      CONFIG_LWIP_AUTOIFACE: 'y'
+      CONFIG_LWIP_IPV4: 'y'
+      CONFIG_LWIP_DHCP: 'n'
+      CONFIG_LWIP_DNS: 'n'
+      CONFIG_LWIP_NUM_TCPCON: 64
+      CONFIG_LWIP_NUM_TCPLISTENERS: 64
+      CONFIG_LWIP_ICMP: 'y'
+  libelf:
+    source: https://github.com/unikraft/lib-libelf
+    version: staging
+
+targets:
+- fc/x86_64
+- qemu/x86_64

library/caddy/2.7/README.md

@@ -0,0 +1,41 @@
+# Caddy 2.7
+
+This directory contains the definition for building the `unikraft.org/caddy:2.7` image.
+
+To run this image, [install Unikraft's companion command-line toolchain `kraft`](https://unikraft.org/docs/cli) and then you can run:
+
+```console
+kraft run -p 2015:2015 unikraft.org/caddy:2.7
+```
+
+To customize the `Caddyfile`, simply provide an alternative path to `/etc/caddy`:
+
+```console
+kraft run -p 2015:2015 -v $(pwd):/etc/caddy unikraft.org/caddy:2.7
+```
+
+Once executed, it will open port `2015` and wait for connections, and can be queried on:
+
+```console
+curl http://localhost:2015
+```
+
+
+## Building and packaging locally
+
+To build this image locally:
+
+```console
+kraft build --no-cache
+```
+
+Then package:
+
+```console
+kraft pkg --name unikraft.org/caddy:2.7 --strategy overwrite
+```
+
+
+## See also
+
+- [How to run unikernels locally in Unikraft's Documentation](https://unikraft.org/docs/cli/running).