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Moves to a safer design where we don't ingest the initial peers.json file.

This commit is contained in:
James Phillips 2016-07-30 00:54:08 -07:00
parent aa4e9daf12
commit 1b633e66c5
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GPG Key ID: 77183E682AC5FC11
1 changed files with 46 additions and 3 deletions
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47
consul/server.go
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@ -4,6 +4,7 @@ import (
"crypto/tls"
"errors"
"fmt"
"io/ioutil"
"log"
"net"
"net/rpc"
@ -402,9 +403,51 @@ func (s *Server) setupRaft() error {
}
snap = snapshots
// If we see a peers.json file, attempt recovery based on it.
// For an existing cluster being upgraded to the new version of
// Raft, we almost never want to run recovery based on the old
// peers.json file. We create a peers.info file with a helpful
// note about where peers.json went, and use that as a sentinel
// to avoid ingesting the old one that first time (if we have to
// create the peers.info file because it's not there, we also
// blow away any existing peers.json file).
peersFile := filepath.Join(path, "peers.json")
peersInfoFile := filepath.Join(path, "peers.info")
if _, err := os.Stat(peersInfoFile); os.IsNotExist(err) {
content := []byte(`
As of Consul 0.7.0, the peers.json file is only used for recovery
after an outage. It should be formatted as a JSON array containing the address
and port of each Consul server in the cluster, like this:
["10.1.0.1:8500","10.1.0.2:8500","10.1.0.3:8500"]
Under normal operation, the peers.json file will not be present.
When Consul starts for the first time, it will create this peers.info file and
delete any existing peers.json file so that recovery doesn't occur on the first
startup.
Once this peers.info file is present, any peers.json file will be ingested at
startup, and will set the Raft peer configuration manually to recover from an
outage. It's crucial that all servers in the cluster are shut down before
creating the peers.json file, and that all servers receive the same
configuration. Once the peers.json file is successfully ingested and applied, it
will be deleted.
Please see https://www.consul.io/docs/guides/outage.html for more information.
`)
if err := ioutil.WriteFile(peersInfoFile, content, 0755); err != nil {
return fmt.Errorf("failed to write peers.info file: %v", err)
}
// Blow away the peers.json file if present, since the
// peers.info sentinel wasn't there.
if _, err := os.Stat(peersFile); err == nil {
if err := os.Remove(peersFile); err != nil {
return fmt.Errorf("failed to delete peers.json, please delete manually (see peers.info for details): %v", err)
}
s.logger.Printf("[INFO] consul: deleted peers.json file (see peers.info for details)")
}
} else if _, err := os.Stat(peersFile); err == nil {
s.logger.Printf("[INFO] consul: found peers.json file, recovering Raft configuration...")
configuration, err := raft.ReadPeersJSON(peersFile)
if err != nil {
@ -419,7 +462,7 @@ func (s *Server) setupRaft() error {
return fmt.Errorf("recovery failed: %v", err)
}
if err := os.Remove(peersFile); err != nil {
return fmt.Errorf("recovery failed to delete peers.json, please delete manually: %v", err)
return fmt.Errorf("recovery failed to delete peers.json, please delete manually (see peers.info for details): %v", err)
}
s.logger.Printf("[INFO] consul: deleted peers.json file after successful recovery")
}