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package clients
import (
"context"
"sync"
"time"
"github.com/mimecast/dtail/internal/clients/connectors"
"github.com/mimecast/dtail/internal/config"
"github.com/mimecast/dtail/internal/discovery"
"github.com/mimecast/dtail/internal/io/dlog"
"github.com/mimecast/dtail/internal/regex"
"github.com/mimecast/dtail/internal/ssh/client"
gossh "golang.org/x/crypto/ssh"
)
// This is the main client data structure.
type baseClient struct {
config.Args
// To display client side stats
stats *stats
// List of remote servers to connect to.
servers []string
// We have one connection per remote server.
connections []connectors.Connector
// SSH auth methods to use to connect to the remote servers.
sshAuthMethods []gossh.AuthMethod
// To deal with SSH host keys
hostKeyCallback client.HostKeyCallback
// Throttle how fast we initiate SSH connections concurrently
throttleCh chan struct{}
// Retry connection upon failure?
retry bool
// Connection maker helper.
maker maker
// Regex is the regular expresion object for line filtering
Regex regex.Regex
}
func (c *baseClient) init() {
dlog.Client.Debug("Initiating base client", c.Args.String())
flag := regex.Default
if c.Args.RegexInvert {
flag = regex.Invert
}
regex, err := regex.New(c.Args.RegexStr, flag)
if err != nil {
dlog.Client.FatalPanic(c.Regex, "Invalid regex!", err, regex)
}
c.Regex = regex
if c.Args.Serverless {
return
}
c.sshAuthMethods, c.hostKeyCallback = client.InitSSHAuthMethods(
c.Args.SSHAuthMethods, c.Args.SSHHostKeyCallback, c.Args.TrustAllHosts,
c.throttleCh, c.Args.SSHPrivateKeyFilePath)
}
func (c *baseClient) makeConnections(maker maker) {
c.maker = maker
discoveryService := discovery.New(c.Discovery, c.ServersStr, discovery.Shuffle)
for _, server := range discoveryService.ServerList() {
c.connections = append(c.connections, c.makeConnection(server,
c.sshAuthMethods, c.hostKeyCallback))
}
c.stats = newTailStats(len(c.connections))
}
func (c *baseClient) Start(ctx context.Context, statsCh <-chan string) (status int) {
dlog.Client.Trace("Starting base client")
// Can be nil when serverless.
if c.hostKeyCallback != nil {
// Periodically check for unknown hosts, and ask the user whether to trust them or not.
go c.hostKeyCallback.PromptAddHosts(ctx)
}
// Print client stats every time something on statsCh is received.
go c.stats.Start(ctx, c.throttleCh, statsCh, c.Args.Quiet)
var wg sync.WaitGroup
wg.Add(len(c.connections))
var mutex sync.Mutex
for i, conn := range c.connections {
go func(i int, conn connectors.Connector) {
defer wg.Done()
connStatus := c.startConnection(ctx, i, conn)
mutex.Lock()
defer mutex.Unlock()
if connStatus > status {
status = connStatus
}
}(i, conn)
}
wg.Wait()
return
}
func (c *baseClient) startConnection(ctx context.Context, i int,
conn connectors.Connector) (status int) {
for {
connCtx, cancel := context.WithCancel(ctx)
defer cancel()
conn.Start(connCtx, cancel, c.throttleCh, c.stats.connectionsEstCh)
// Retrieve status code from handler (dtail client will exit with that status)
status = conn.Handler().Status()
// Do we want to retry?
if !c.retry {
// No, we don't.
return
}
select {
case <-ctx.Done():
// No, context is done, so no retry.
return
default:
}
// Yes, we want to retry.
time.Sleep(time.Second * 2)
dlog.Client.Debug(conn.Server(), "Reconnecting")
conn = c.makeConnection(conn.Server(), c.sshAuthMethods, c.hostKeyCallback)
c.connections[i] = conn
}
}
func (c *baseClient) makeConnection(server string, sshAuthMethods []gossh.AuthMethod,
hostKeyCallback client.HostKeyCallback) connectors.Connector {
if c.Args.Serverless {
return connectors.NewServerless(c.UserName, c.maker.makeHandler(server),
c.maker.makeCommands())
}
return connectors.NewServerConnection(server, c.UserName, sshAuthMethods,
hostKeyCallback, c.maker.makeHandler(server), c.maker.makeCommands())
}
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