[lxc-devel] [distrobuilder/master] Add lxd-agent generator

[monstermunchkin on Github]

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From b68eca381b74b78db6d80bba8bce0a6791a4e12c Mon Sep 17 00:00:00 2001
From: Thomas Hipp <thomas.hipp at canonical.com>
Date: Thu, 13 Feb 2020 16:40:14 +0100
Subject: [PATCH 1/2] generators: Add lxd-agent generator

Signed-off-by: Thomas Hipp <thomas.hipp at canonical.com>
---
 generators/generators.go |  6 +++
 generators/lxd-agent.go  | 83 ++++++++++++++++++++++++++++++++++++++++
 shared/definition.go     |  1 +
 3 files changed, 90 insertions(+)
 create mode 100644 generators/lxd-agent.go

diff --git a/generators/generators.go b/generators/generators.go
index 3842852..2080e86 100644
--- a/generators/generators.go
+++ b/generators/generators.go
@@ -1,6 +1,7 @@
 package generators
 
 import (
+	"errors"
 	"os"
 	p "path"
 	"path/filepath"
@@ -12,6 +13,9 @@ import (
 	"github.com/lxc/distrobuilder/shared"
 )
 
+// ErrNotSupported returns a "Not supported" error
+var ErrNotSupported = errors.New("Not supported")
+
 // Generator interface.
 type Generator interface {
 	RunLXC(string, string, *image.LXCImage, shared.DefinitionFile) error
@@ -36,6 +40,8 @@ func Get(generator string) Generator {
 		return UpstartTTYGenerator{}
 	case "cloud-init":
 		return CloudInitGenerator{}
+	case "lxd-agent":
+		return LXDAgentGenerator{}
 	}
 
 	return nil
diff --git a/generators/lxd-agent.go b/generators/lxd-agent.go
new file mode 100644
index 0000000..8cae145
--- /dev/null
+++ b/generators/lxd-agent.go
@@ -0,0 +1,83 @@
+package generators
+
+import (
+	"io/ioutil"
+	"os"
+	"path/filepath"
+
+	"github.com/lxc/distrobuilder/image"
+	"github.com/lxc/distrobuilder/shared"
+)
+
+// LXDAgentGenerator represents the lxd-agent generator.
+type LXDAgentGenerator struct{}
+
+// RunLXC is not supported.
+func (g LXDAgentGenerator) RunLXC(cacheDir, sourceDir string, img *image.LXCImage, defFile shared.DefinitionFile) error {
+	return ErrNotSupported
+}
+
+// RunLXD creates systemd unit files for the lxd-agent.
+func (g LXDAgentGenerator) RunLXD(cacheDir, sourceDir string, img *image.LXDImage, defFile shared.DefinitionFile) error {
+	lxdAgentServiceUnit := `[Unit]
+Description=LXD - agent
+Documentation=https://linuxcontainers.org/lxd
+ConditionPathExists=/dev/virtio-ports/org.linuxcontainers.lxd
+Requires=lxd-agent-9p.service
+After=lxd-agent-9p.service
+Before=cloud-init.target
+
+[Service]
+Type=simple
+WorkingDirectory=/run/lxd_config/9p
+ExecStart=/run/lxd_config/9p/lxd-agent
+
+[Install]
+WantedBy=multi-user.target
+`
+
+	err := ioutil.WriteFile(filepath.Join(sourceDir, "/lib/systemd/lxd-agent.service"), []byte(lxdAgentServiceUnit), 0400)
+	if err != nil {
+		return err
+	}
+
+	err = os.Symlink(filepath.Join(sourceDir, "/lib/systemd/system/lxd-agent.service"), "/etc/systemd/system/multi-user.target.wants/lxd-agent.service")
+	if err != nil {
+		return err
+	}
+
+	lxdConfigShareMountUnit := `[Unit]
+Description=LXD - agent - 9p mount
+Documentation=https://linuxcontainers.org/lxd
+ConditionPathExists=/dev/virtio-ports/org.linuxcontainers.lxd
+
+[Service]
+Type=oneshot
+RemainAfterExit=yes
+ExecStartPre=-/sbin/modprobe 9pnet_virtio
+ExecStartPre=/bin/mkdir -p /run/lxd_config/9p
+ExecStartPre=/bin/chmod 0700 /run/lxd_config/
+ExecStart=/bin/mount -t 9p config /run/lxd_config/9p -o access=0
+
+[Install]
+WantedBy=multi-user.target
+`
+
+	err = ioutil.WriteFile(filepath.Join(sourceDir, "/lib/systemd/lxd-agent-9p.service"), []byte(lxdConfigShareMountUnit), 0400)
+	if err != nil {
+		return err
+	}
+
+	err = os.Symlink(filepath.Join(sourceDir, "/lib/systemd/system/lxd-agent-9p.service"), "/etc/systemd/system/multi-user.target.wants/lxd-agent-9p.service")
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// Run does nothing.
+func (g LXDAgentGenerator) Run(cacheDir, sourceDir string,
+	defFile shared.DefinitionFile) error {
+	return nil
+}
diff --git a/shared/definition.go b/shared/definition.go
index 7b586d5..b74fb5a 100644
--- a/shared/definition.go
+++ b/shared/definition.go
@@ -352,6 +352,7 @@ func (d *Definition) Validate() error {
 		"remove",
 		"upstart-tty",
 		"cloud-init",
+		"lxd-agent",
 	}
 
 	for _, file := range d.Files {

From e2c7d53e78002feefcc0c107eae5dcef7283e291 Mon Sep 17 00:00:00 2001
From: Thomas Hipp <thomas.hipp at canonical.com>
Date: Fri, 14 Feb 2020 09:51:33 +0100
Subject: [PATCH 2/2] doc: Add lxd-agent generator

Signed-off-by: Thomas Hipp <thomas.hipp at canonical.com>
---
 doc/generators.md | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/doc/generators.md b/doc/generators.md
index 61eaa46..74b613c 100644
--- a/doc/generators.md
+++ b/doc/generators.md
@@ -82,3 +82,7 @@ See [LXD image format](https://lxd.readthedocs.io/en/latest/image-handling/#imag
 
 This generator creates an upstart job which prevents certain TTYs from starting.
 The job script is written to `path`.
+
+## lxd-agent
+
+This generator creates the systemd unit files which are needed to start the lxd-agent in LXD VMs.