ecrou/snap/snapcraft.yaml

name: ecrou
base: core26
adopt-info: ecrou
title: ecrou
summary: a small microVM runtime based on libkrun
description: |
  ecrou boots disposable Linux environments as one-shot microVMs on
  libkrun: it resolves an image reference, boots the microVM,
  runs the command, and throws the machine away.
  Volume sharing `-v` and other features are available.

  ## Install

  ecrou is strictly confined.

      sudo snap install ecrou

  ## First run

  Connect the KVM interface:

      sudo snap connect ecrou:kvm

  Then run a microVM:

      ecrou run -it ubuntu

  ## Diagnostics

  `ecrou probe` reports what a run would find: KVM, libkrun, the
  cache directory.

  ## Configuration and cache

  - image cache: `~/snap/ecrou/common/cache/ecrou`

license: MIT
website: https://github.com/vhaudiquet/ecrou
contact: https://github.com/vhaudiquet/ecrou/issues
issues: https://github.com/vhaudiquet/ecrou/issues
source-code: https://github.com/vhaudiquet/ecrou
grade: stable
confinement: strict

platforms:
  amd64:
  arm64:
  riscv64:

apps:
  ecrou:
    command: bin/ecrou
    command-chain: [command-chain/ecrou-env]
    plugs:
      - home
      - network
      - kvm

parts:
  ecrou:
    plugin: rust
    source: .
    rust-channel: "1.98.1"
    rust-path: [crates/ecrou-cli]
    build-packages: [cmake, perl]
    # mkfs.ext4 builds the cache image and debugfs provisions it; both
    # ship in e2fsprogs and run as child processes of the binary.
    # Populating from a tarball is dlopen("libarchive.so.13") at
    # runtime — no hard dependency, so staging e2fsprogs alone leaves
    # the run failing with "you need libarchive"; stage the lib too.
    stage-packages: [e2fsprogs, libarchive13t64]
    override-pull: |
      craftctl default
      # [workspace.package] version — the single `version = "..."` at
      # the head of the workspace manifest. A missed match fails the
      # pack loudly instead of packing a versionless snap.
      craftctl set version="$(sed -n 's/^version = "\(.*\)"/\1/p' \
        "$CRAFT_PART_SRC/Cargo.toml")"
    override-build: |
      craftctl default
      # The home interface stops at dotfiles, so ~/.cache is
      # unreachable under strict confinement. Point the XDG cache
      # lookup (the dirs crate honors the variable) into the snap's
      # durable area, shared across refreshes.
      mkdir -p "$CRAFT_PART_INSTALL/command-chain"
      cat > "$CRAFT_PART_INSTALL/command-chain/ecrou-env" <<'EOF'
      #!/bin/sh
      XDG_CACHE_HOME="$SNAP_USER_COMMON/cache"
      export XDG_CACHE_HOME
      mkdir -p "$XDG_CACHE_HOME"
      exec "$@"
      EOF
      chmod 755 "$CRAFT_PART_INSTALL/command-chain/ecrou-env"

  libkrun:
    plugin: rust
    source: https://github.com/containers/libkrun
    source-type: git
    source-tag: v1.19.7
    source-depth: 1
    rust-channel: "1.98.1"
    override-build: |
      # blk turns on the virtio-blk device: the rootfs crosses as a
      # raw ext4 image (krun_add_disk + krun_set_root_disk_remount),
      # which is what makes guest-side chown work.
      cargo build --release -p libkrun --features net,blk
      install -Dm755 target/release/libkrun.so \
        "$CRAFT_PART_INSTALL/lib/libkrun.so.1.19.7"
      ln -s libkrun.so.1.19.7 "$CRAFT_PART_INSTALL/lib/libkrun.so.1"

  libkrunfw:
    plugin: nil
    # libkrunfw5 ships only in stonking universe today, not in any LTS
    # base, so the .deb comes straight from the Ubuntu archive — one
    # flavor per target arch. riscv64 lives on the ports archive
    # (archive.ubuntu.com carries amd64 and arm64 binaries only). The
    # library embeds its kernel and has no external symbols, so it
    # runs on the base's older glibc.
    build-packages: [curl]
    override-pull: |
      arch="$CRAFT_ARCH_BUILD_FOR"
      case "$arch" in
        amd64)
          digest="924cd545080aaf5da66740d12a51b7a5cbd9a5c0b502d21cbef9bc82bf1c8b6b"
          pool="https://archive.ubuntu.com/ubuntu/pool/universe/libk/libkrunfw" ;;
        arm64)
          digest="9570e82feac79fd41a6a9674cc02a9b2f09948ac30ad480d05fc73a957843e56"
          pool="https://archive.ubuntu.com/ubuntu/pool/universe/libk/libkrunfw" ;;
        riscv64)
          digest="1f8b52a00eafdf52d2295eeab7dd527736788ce4d3aa97aecc18e3f4b66f413f"
          pool="https://ports.ubuntu.com/ubuntu-ports/pool/universe/libk/libkrunfw" ;;
        *) echo "no libkrunfw5 .deb mapped for $arch" >&2; exit 1 ;;
      esac
      curl -fL -o libkrunfw5.deb "$pool/libkrunfw5_5.5.0+ds-1_${arch}.deb"
      echo "$digest  libkrunfw5.deb" | sha256sum -c
    override-build: |
      dpkg -x libkrunfw5.deb unpack
      install -Dm755 "unpack/usr/lib/${CRAFT_ARCH_TRIPLET_BUILD_FOR}/libkrunfw.so.5.5.0" \
        "$CRAFT_PART_INSTALL/lib/libkrunfw.so.5.5.0"
      ln -s libkrunfw.so.5.5.0 "$CRAFT_PART_INSTALL/lib/libkrunfw.so.5"