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It can be accessed and reviewed at: https://github.com/lxc/lxd/pull/6738
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=== Description (from pull-request) ===
Periodically repopulates STARTED status into vserial ringbuffer so LXD can restablish agent status after LXD restarts.
Signed-off-by: Thomas Parrott <thomas.parr...@canonical.com>
From 641045749556335c355fc385c7f0a47f5ca7f1fc Mon Sep 17 00:00:00 2001
From: Thomas Parrott <thomas.parr...@canonical.com>
Date: Mon, 20 Jan 2020 12:56:39 +0000
Subject: [PATCH] lxd-agent: Fixes bug when agent not seen as started if LXD
restarted
Periodically repopulates STARTED status into vserial ringbuffer so LXD can
restablish agent status after LXD restarts.
Signed-off-by: Thomas Parrott <thomas.parr...@canonical.com>
---
lxd-agent/main_agent.go | 62 +++++++++++++++++++++++++++++++----------
1 file changed, 48 insertions(+), 14 deletions(-)
diff --git a/lxd-agent/main_agent.go b/lxd-agent/main_agent.go
index b93abf837e..3a6aaf9fa9 100644
--- a/lxd-agent/main_agent.go
+++ b/lxd-agent/main_agent.go
@@ -1,9 +1,12 @@
package main
import (
+ "context"
+ "fmt"
"os"
"os/signal"
"path/filepath"
+ "time"
"github.com/pkg/errors"
"github.com/spf13/cobra"
@@ -97,25 +100,56 @@ func (c *cmdAgent) Run(cmd *cobra.Command, args []string)
error {
// Prepare the HTTP server.
httpServer := restServer(tlsConfig, cert, c.global.flagLogDebug, d)
- // Serial notification.
+ // Create a cancellation context.
+ ctx, cancelFunc := context.WithCancel(context.Background())
+
+ // Start status notifier in background.
+ go c.startStatusNotifier(ctx)
+
+ // Cancel context when SIGTEM is received.
+ chSignal := make(chan os.Signal, 1)
+ signal.Notify(chSignal, unix.SIGTERM)
+ go func() {
+ <-chSignal
+ cancelFunc()
+ os.Exit(0)
+ }()
+
+ // Start the server.
+ return httpServer.ServeTLS(networkTLSListener(l, tlsConfig),
"agent.crt", "agent.key")
+}
+
+// startStatusNotifier sends status of agent to vserial ring buffer every 10s
or when context is done.
+func (c *cmdAgent) startStatusNotifier(ctx context.Context) {
+ ticker := time.NewTicker(time.Duration(time.Second) * 10)
+ defer ticker.Stop()
+
+ // Write initial started status.
+ c.writeStatus("STARTED")
+
+ for {
+ select {
+ case <-ticker.C:
+ // Re-populate status periodically in case LXD restarts.
+ c.writeStatus("STARTED")
+ case <-ctx.Done():
+ // Indicate we are stopping to LXD.
+ c.writeStatus("STOPPED")
+ return
+ }
+ }
+}
+
+// writeStatus writes a status code to the vserial ring buffer used to detect
agent status on host.
+func (c *cmdAgent) writeStatus(status string) error {
if shared.PathExists("/dev/virtio-ports/org.linuxcontainers.lxd") {
vSerial, err :=
os.OpenFile("/dev/virtio-ports/org.linuxcontainers.lxd", os.O_RDWR, 0600)
if err != nil {
return err
}
- defer vSerial.Close()
-
- vSerial.Write([]byte("STARTED\n"))
-
- chSignal := make(chan os.Signal, 1)
- signal.Notify(chSignal, unix.SIGTERM)
- go func() {
- <-chSignal
- vSerial.Write([]byte("STOPPED\n"))
- os.Exit(0)
- }()
+ vSerial.Write([]byte(fmt.Sprintf("%s\n", status)))
+ vSerial.Close()
}
- // Start the server.
- return httpServer.ServeTLS(networkTLSListener(l, tlsConfig),
"agent.crt", "agent.key")
+ return nil
}
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