systemd: Introduce common templates

We already use templating to generate sockets, which are all
based off libvirtd's. Push the idea further, and extend it to
cover services as well.

This is more challenging, as the various modular daemons each have
their own needs in terms of what system services needs to be
available before they can be started, which other components of
libvirt they depend on, and so on.

In order to make this sort of per-service tweaks possible, we
introduce a Python script that can merge two systemd units
together. The script is aware of the semantics of systemd's unit
definition format, so it can intelligently merge sections
together.

This generic systemd unit merging mechanism will also supersede
the extremely ad-hoc @deps@ variable, which is currently used in
a single scenario.

Signed-off-by: Andrea Bolognani <abologna@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>

diff --git a/scripts/merge-systemd-units.py b/scripts/merge-systemd-units.py
new file mode 100755 (executable)
index 0000000..bc33212
--- /dev/null
+++ b/scripts/merge-systemd-units.py
@@ -0,0 +1,94 @@
+#!/usr/bin/env python3
+
+# Copyright (C) 2023 Red Hat, Inc.
+# SPDX-License-Identifier: LGPL-2.1-or-later
+
+import sys
+
+SECTIONS = [
+    "[Unit]",
+    "[Service]",
+    "[Socket]",
+    "[Install]",
+]
+
+
+def parse_unit(unit_path):
+    unit = {}
+    current_section = "[Invalid]"
+
+    with open(unit_path) as f:
+        for line in f:
+            line = line.strip()
+
+            if line == "":
+                continue
+
+            if line[0] == "[" and line[-1] == "]":
+                if line not in SECTIONS:
+                    print("Unknown section {}".format(line))
+                    sys.exit(1)
+
+                current_section = line
+                continue
+
+            if current_section not in unit:
+                unit[current_section] = []
+
+            unit[current_section].append(line)
+
+    if "[Invalid]" in unit:
+        print("Contents found outside of any section")
+        sys.exit(1)
+
+    return unit
+
+
+def format_unit(unit):
+    lines = []
+
+    for section in SECTIONS:
+        if section not in unit:
+            continue
+
+        lines.append(section)
+
+        for line in unit[section]:
+            lines.append(line)
+
+        lines.append("")
+
+    return "\n".join(lines)
+
+
+def merge_units(base, extra):
+    merged = {}
+
+    for section in SECTIONS:
+        if section in extra and section not in base:
+            print("Section {} in extra but not in base".format(section))
+            sys.exit(1)
+
+        if section not in base:
+            continue
+
+        merged[section] = base[section]
+
+        if section not in extra:
+            continue
+
+        merged[section].extend(extra[section])
+
+    return merged
+
+
+if len(sys.argv) < 2:
+    print("usage: {} BASE EXTRA".format(sys.argv[0]))
+    sys.exit(1)
+
+base = parse_unit(sys.argv[1])
+extra = parse_unit(sys.argv[2])
+
+merged = merge_units(base, extra)
+
+sys.stdout.write(format_unit(merged))

diff --git a/scripts/meson.build b/scripts/meson.build
index 05b71184f117247198305791f100854897c0f93a..65fd1e21c54996bd98e6f580311c0adf790f51c5 100644 (file)
--- a/scripts/meson.build
+++ b/scripts/meson.build
@@ -19,6 +19,7 @@ scripts = [
   'header-ifdef.py',
   'hvsupport.py',
   'hyperv_wmi_generator.py',
+  'merge-systemd-units.py',
   'meson-dist.py',
   'meson-gen-authors.py',
   'meson-gen-def.py',

diff --git a/src/meson.build b/src/meson.build
index 2fbf98b9fe2684867d2c1ba12a5d6409e7831723..02c92621baa4cef736e3dd568371fc430292a3b4 100644 (file)
--- a/src/meson.build
+++ b/src/meson.build
@@ -203,6 +203,8 @@ libvirtd_socket_admin_in = files('remote' / 'libvirtd-admin.socket.in')
 #   * sockets - array of additional sockets (optional, default [ 'main', 'ro', 'admin' ])
 #   * service_in - service source file (optional, default remote/libvirtd.service.in)
 #   * socket_$name_in - additional socket source files (optional, default remote/libvirtd.socket.in )
+#   * service_extra_in - unit to merge with service_in (optional, default None)
+#   * socket_extra_in - unit to merge with socket_$name_in (optional, default None)
 #   * deps - socket dependencies (optional, default '')
 virt_daemon_units = []
 
@@ -817,6 +819,7 @@ if conf.has('WITH_LIBVIRTD')
         'initconfdir': initconfdir,
         'name': unit['name'],
         'service': unit['service'],
+        'SERVICE': unit['service'].to_upper(),
         'sockprefix': unit.get('sockprefix', unit['service']),
         'deps': unit.get('deps', ''),
         'sockmode': sockmode,
@@ -825,6 +828,15 @@ if conf.has('WITH_LIBVIRTD')
       service_in = unit.get('service_in', service_in_default)
       service_out = '@0@.service'.format(unit['service'])
 
+      if 'service_extra_in' in unit
+        service_in = configure_file(
+          input: [ service_in, unit['service_extra_in'] ],
+          output: '@0@.in'.format(service_out),
+          command: [ merge_systemd_units_prog, '@INPUT0@', '@INPUT1@' ],
+          capture: true,
+        )
+      endif
+
       configure_file(
         input: service_in,
         output: service_out,
@@ -843,6 +855,16 @@ if conf.has('WITH_LIBVIRTD')
           socket_in = unit.get('socket_@0@_in'.format(socket), socket_in_default)
           socket_out = '@0@-@1@.socket'.format(unit['service'], socket)
         endif
+
+        if 'socket_extra_in' in unit
+          socket_in = configure_file(
+            input: [ socket_in, unit['socket_extra_in'] ],
+            output: '@0@.in'.format(socket_out),
+            command: [ merge_systemd_units_prog, '@INPUT0@', '@INPUT1@' ],
+            capture: true,
+          )
+        endif
+
         configure_file(
           input: socket_in,
           output: socket_out,

diff --git a/src/virtd-admin.socket.in b/src/virtd-admin.socket.in
new file mode 100644 (file)
index 0000000..39bb0ba
--- /dev/null
+++ b/src/virtd-admin.socket.in
@@ -0,0 +1,13 @@
+[Unit]
+Description=@name@ admin socket
+Before=@service@.service
+BindsTo=@service@.socket
+After=@service@.socket
+
+[Socket]
+ListenStream=@runstatedir@/libvirt/@sockprefix@-admin-sock
+Service=@service@.service
+SocketMode=0600
+
+[Install]
+WantedBy=sockets.target

diff --git a/src/virtd-ro.socket.in b/src/virtd-ro.socket.in
new file mode 100644 (file)
index 0000000..b7b7ae0
--- /dev/null
+++ b/src/virtd-ro.socket.in
@@ -0,0 +1,13 @@
+[Unit]
+Description=@name@ local read-only socket
+Before=@service@.service
+BindsTo=@service@.socket
+After=@service@.socket
+
+[Socket]
+ListenStream=@runstatedir@/libvirt/@sockprefix@-sock-ro
+Service=@service@.service
+SocketMode=0666
+
+[Install]
+WantedBy=sockets.target

diff --git a/src/virtd-tcp.socket.in b/src/virtd-tcp.socket.in
new file mode 100644 (file)
index 0000000..7c8bcdb
--- /dev/null
+++ b/src/virtd-tcp.socket.in
@@ -0,0 +1,12 @@
+[Unit]
+Description=@name@ non-TLS IP socket
+Before=@service@.service
+BindsTo=@service@.socket
+After=@service@.socket
+
+[Socket]
+ListenStream=16509
+Service=@service@.service
+
+[Install]
+WantedBy=sockets.target

diff --git a/src/virtd-tls.socket.in b/src/virtd-tls.socket.in
new file mode 100644 (file)
index 0000000..c6dceb2
--- /dev/null
+++ b/src/virtd-tls.socket.in
@@ -0,0 +1,12 @@
+[Unit]
+Description=@name@ TLS IP socket
+Before=@service@.service
+BindsTo=@service@.socket
+After=@service@.socket
+
+[Socket]
+ListenStream=16514
+Service=@service@.service
+
+[Install]
+WantedBy=sockets.target

diff --git a/src/virtd.service.in b/src/virtd.service.in
new file mode 100644 (file)
index 0000000..76f9c60
--- /dev/null
+++ b/src/virtd.service.in
@@ -0,0 +1,25 @@
+[Unit]
+Description=@name@ daemon
+Conflicts=libvirtd.service
+Requires=@service@.socket
+Requires=@service@-ro.socket
+Requires=@service@-admin.socket
+After=network.target
+After=dbus.service
+After=apparmor.service
+Documentation=man:@service@(8)
+Documentation=https://libvirt.org
+
+[Service]
+Type=notify
+Environment=@SERVICE@_ARGS="--timeout 120"
+EnvironmentFile=-@initconfdir@/@service@
+ExecStart=@sbindir@/@service@ $@SERVICE@_ARGS
+ExecReload=/bin/kill -HUP $MAINPID
+Restart=on-failure
+
+[Install]
+WantedBy=multi-user.target
+Also=@service@.socket
+Also=@service@-ro.socket
+Also=@service@-admin.socket

diff --git a/src/virtd.socket.in b/src/virtd.socket.in
new file mode 100644 (file)
index 0000000..aec0708
--- /dev/null
+++ b/src/virtd.socket.in
@@ -0,0 +1,12 @@
+[Unit]
+Description=@name@ local socket
+Before=@service@.service
+
+[Socket]
+ListenStream=@runstatedir@/libvirt/@sockprefix@-sock
+Service=@service@.service
+SocketMode=@sockmode@
+RemoveOnStop=yes
+
+[Install]
+WantedBy=sockets.target