Feature set (arch pkgbuild, intent, migration)

BUILD.linux.md

@@ -1,6 +1,57 @@
 # Build instructions for Linux
 
-## Environment Setup
+## Arch Linux
+
+Build and package the full stack (`elpd` daemon, `elp` CLI, `elp` GUI) as an
+installable Arch package:
+
+```
+sudo pacman -S devtools
+./scripts/build-arch.sh
+```
+
+This renders [`packaging/archlinux/PKGBUILD.in`](packaging/archlinux/PKGBUILD.in)
+against the current checkout and builds it in a clean, sandboxed chroot via
+devtools' `extra-x86_64-build` (bootstrapped automatically on first run).
+Pass `--no-sandbox` to build with a plain `makepkg` in the current
+environment instead (you'll need every package listed in the rendered
+PKGBUILD's `depends`/`makedepends` installed yourself). See
+`./scripts/build-arch.sh --help` for all options.
+
+The build compiles Qt6, gRPC, Boost, and QEMU from source via vcpkg (see
+`vcpkg.json`) — but only the **first** time: the script bind-mounts a
+persistent cache directory (`build/vcpkg-binary-cache` by default) into the
+chroot and points vcpkg's binary cache at it, so later builds, even in a
+freshly recreated chroot, reuse those binaries instead of recompiling them.
+Delete that directory to force a full rebuild from scratch.
+
+Install the resulting package with `pacman -U <package>.pkg.tar.zst`; this
+installs `elpd`/`elp`/the GUI, desktop/icon/completion files, and two
+systemd units you need to enable yourself (packages don't auto-enable
+services on Arch):
+
+```
+sudo systemctl enable --now elpd elp-api
+```
+
+`elp-api` is the REST/gateway sidecar (`https://127.0.0.1:7777`) the GUI
+uses for things like the catalogue's per-service gateway CA fetch — without
+it running, deploying anything from the Catalogue fails with a connection-
+refused error trying to reach `127.0.0.1:7777/ca.crt`.
+
+Migrating an instance/intent to another host (`elp migrate`, or the GUI's
+"Migrate" action) also needs:
+- `avahi-daemon.service` running (`sudo systemctl enable --now avahi-daemon`)
+  for elpd to advertise/discover other hosts on the network. This is
+  optional — migration itself still works with a manually-added host (GUI's
+  Migration Hosts page, or `elp migrate --to user@host` directly); avahi is
+  only what populates the automatic "discovered on network" list.
+- Working SSH access (key-based, no password prompt) from this machine to
+  the target as the user given in `user@host` — migration shells out to
+  `ssh`/`rsync` under the hood, using your own `~/.ssh/config`/agent, and
+  `elp` already installed with its daemon running on the target.
+
+## Ubuntu / apt-based distributions
 
 ### Build dependencies
 

data/cloud-init-yaml/cloud-init-postgres.yaml

@@ -0,0 +1,14 @@
+# Reference copy of the "postgres" service template used by `elp intent
+# create --service postgres`; the daemon embeds this content directly
+# (src/daemon/intent_service_templates.cpp) rather than reading this file.
+packages:
+- postgresql
+
+runcmd:
+- |
+  echo "listen_addresses = '*'" >> /etc/postgresql/*/main/postgresql.conf
+  echo "host all all 0.0.0.0/0 md5" >> /etc/postgresql/*/main/pg_hba.conf
+  systemctl enable postgresql --now
+  systemctl restart postgresql
+
+final_message: "postgres is up, after $UPTIME seconds"

data/cloud-init-yaml/cloud-init-redis.yaml

@@ -0,0 +1,12 @@
+# Reference copy of the "redis" service template used by `elp intent create
+# --service redis`; the daemon embeds this content directly
+# (src/daemon/intent_service_templates.cpp) rather than reading this file.
+packages:
+- redis-server
+
+runcmd:
+- |
+  sed -i 's/^bind 127.0.0.1.*/bind 0.0.0.0/' /etc/redis/redis.conf
+  systemctl enable redis-server --now
+
+final_message: "redis is up, after $UPTIME seconds"

include/multipass/intent_spec.h

@@ -0,0 +1,56 @@
+/*
+ * Copyright (C) Elemento.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 3.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#pragma once
+
+#include <boost/json.hpp>
+
+#include <string>
+#include <vector>
+
+namespace multipass
+{
+
+// A named group of instances launched together (e.g. "test-app-1" made of a
+// redis and a postgres instance). Membership is also mirrored into each
+// member instance's own VMSpecs.metadata ("intent"/"intent_role"); this
+// registry is the source of truth for the group itself (name, ordered
+// members, creation time), independent of any single member.
+struct IntentSpec
+{
+    struct Member
+    {
+        std::string role;          // e.g. "redis", or a user-chosen label for inline members
+        std::string instance_name; // the launched VM instance's name, or an LLM session's instance_id
+        std::string kind{"vm"};    // "vm" or "llm"; defaults to "vm" for older persisted records
+
+        friend inline bool operator==(const Member&, const Member&) = default;
+    };
+
+    std::string name;
+    std::vector<Member> members;
+    std::string creation_timestamp; // ISO-8601
+
+    friend inline bool operator==(const IntentSpec&, const IntentSpec&) = default;
+};
+
+void tag_invoke(const boost::json::value_from_tag&,
+               boost::json::value& json,
+               const IntentSpec& spec);
+IntentSpec tag_invoke(const boost::json::value_to_tag<IntentSpec>&, const boost::json::value& json);
+
+} // namespace multipass

include/multipass/mdns_service.h

@@ -0,0 +1,84 @@
+/*
+ * Copyright (C) Elemento.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 3.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#pragma once
+
+#include <QObject>
+
+#include <memory>
+#include <string>
+
+namespace multipass
+{
+
+// Advertised/discovered over the "_elp._tcp" mDNS service type. host_name/host_os/host_arch
+// mirror DaemonInfoReply's own fields (see daemon_info's handler); a peer's label is its mDNS
+// service instance name (not necessarily its host_name).
+struct MdnsHostInfo
+{
+    std::string label;
+    std::string address; // resolved IP (or hostname, if resolution only gets that far)
+    std::string host_name;
+    std::string host_os;
+    std::string host_arch;
+    std::string backend;
+};
+
+struct MdnsAdvertisement
+{
+    std::string label; // mDNS service instance name for this daemon; default: host_name
+    std::string host_name;
+    std::string host_os;
+    std::string host_arch;
+    std::string backend;
+};
+
+// Advertises this elpd as "_elp._tcp" on the local network and browses for other instances
+// of it, so the GUI's migration screen can offer a live list of candidate hosts alongside the
+// manually-added "known hosts" list (list_network_hosts merges both — see Daemon::migrate's
+// own doc comment on why migration itself doesn't talk to a peer's elpd directly: this service
+// is purely informational/discovery, migration itself goes over SSH to the target's own CLI).
+class MdnsService : public QObject
+{
+    Q_OBJECT
+public:
+    ~MdnsService() override = default;
+
+    // Begins advertising + browsing. Safe to call once; browsing/advertising continue until
+    // this object is destroyed. Never throws — failures (no mDNS daemon reachable, etc.) are
+    // logged and leave this a permanently-inert no-op rather than taking elpd down with it.
+    virtual void start() = 0;
+
+signals:
+    // Always emitted on this object's own thread; connect with an auto/queued connection to
+    // observe from Daemon's thread (see mdns_service_linux.cpp/mdns_service_macos.cpp — both
+    // run their platform library's event loop on a dedicated worker thread).
+    void host_discovered(multipass::MdnsHostInfo info);
+    void host_removed(std::string label);
+
+protected:
+    MdnsService();
+};
+
+// Returns a platform-appropriate implementation (Avahi on Linux, Bonjour/dns_sd on macOS), or
+// a permanently-inert no-op elsewhere (e.g. Windows) so callers never need to branch on
+// platform themselves.
+std::unique_ptr<MdnsService> make_mdns_service(MdnsAdvertisement advertisement);
+
+} // namespace multipass
+
+Q_DECLARE_METATYPE(multipass::MdnsHostInfo)

include/multipass/vm_specs.h

@@ -49,6 +49,13 @@ struct VMSpecs
     // Marketplace service template id (e.g. caddy_ca_v1). Stored outside QEMU
     // metadata so backend metadata refreshes cannot wipe it.
     std::string service_id;
+    // The image alias/cloud-init this instance was originally launched with
+    // (as given to LaunchRequest, not the resolved local VMImage/YAML::Node
+    // this becomes once prepared) — otherwise discarded after launch, but
+    // needed to redefine the same instance elsewhere (migration).
+    std::string image;
+    std::string cloud_init_user_data;
+    std::string remote_name;
 
     friend inline bool operator==(const VMSpecs& a, const VMSpecs& b) = default;
 };