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plugin.go
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plugin.go
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// Copyright 2016-2018, Pulumi Corporation.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package plugin
import (
"bufio"
"io"
"os"
"os/exec"
"strconv"
"strings"
"sync/atomic"
"time"
multierror "github.com/hashicorp/go-multierror"
"github.com/pkg/errors"
"golang.org/x/net/context"
"google.golang.org/grpc"
"google.golang.org/grpc/codes"
"google.golang.org/grpc/connectivity"
"google.golang.org/grpc/status"
"github.com/pulumi/pulumi/pkg/diag"
"github.com/pulumi/pulumi/pkg/util/cmdutil"
"github.com/pulumi/pulumi/pkg/util/contract"
"github.com/pulumi/pulumi/pkg/util/logging"
"github.com/pulumi/pulumi/pkg/util/rpcutil"
)
type plugin struct {
stdoutDone <-chan bool
stderrDone <-chan bool
Bin string
Args []string
Conn *grpc.ClientConn
Proc *os.Process
Stdin io.WriteCloser
Stdout io.ReadCloser
Stderr io.ReadCloser
}
// pluginRPCConnectionTimeout dictates how long we wait for the plugin's RPC to become available.
var pluginRPCConnectionTimeout = time.Second * 10
// A unique ID provided to the output stream of each plugin. This allows the output of the plugin
// to be streamed to the display, while still allowing that output to be sent a small piece at a
// time.
var nextStreamID int32
func newPlugin(ctx *Context, bin string, prefix string, args []string) (*plugin, error) {
if logging.V(9) {
var argstr string
for i, arg := range args {
if i > 0 {
argstr += ","
}
argstr += arg
}
logging.V(9).Infof("Launching plugin '%v' from '%v' with args: %v", prefix, bin, argstr)
}
// Try to execute the binary.
plug, err := execPlugin(bin, args, ctx.Pwd)
if err != nil {
return nil, errors.Wrapf(err, "failed to load plugin %s", bin)
}
contract.Assert(plug != nil)
// If we did not successfully launch the plugin, we still need to wait for stderr and stdout to drain.
defer func() {
if plug.Conn == nil {
contract.IgnoreError(plug.Close())
}
}()
outStreamID := atomic.AddInt32(&nextStreamID, 1)
errStreamID := atomic.AddInt32(&nextStreamID, 1)
// For now, we will spawn goroutines that will spew STDOUT/STDERR to the relevant diag streams.
runtrace := func(t io.Reader, stderr bool, done chan<- bool) {
reader := bufio.NewReader(t)
for {
msg, readerr := reader.ReadString('\n')
if readerr != nil {
break
}
if strings.TrimSpace(msg) != "" {
if stderr {
ctx.Diag.Infoerrf(diag.StreamMessage("" /*urn*/, msg, errStreamID))
} else {
ctx.Diag.Infof(diag.StreamMessage("" /*urn*/, msg, outStreamID))
}
}
}
close(done)
}
// Set up a tracer on stderr before going any further, since important errors might get communicated this way.
stderrDone := make(chan bool)
plug.stderrDone = stderrDone
go runtrace(plug.Stderr, true, stderrDone)
// Now that we have a process, we expect it to write a single line to STDOUT: the port it's listening on. We only
// read a byte at a time so that STDOUT contains everything after the first newline.
var port string
b := make([]byte, 1)
for {
n, readerr := plug.Stdout.Read(b)
if readerr != nil {
killerr := plug.Proc.Kill()
contract.IgnoreError(killerr) // we are ignoring because the readerr trumps it.
if port == "" {
return nil, errors.Wrapf(readerr, "could not read plugin [%v] stdout", bin)
}
return nil, errors.Wrapf(readerr, "failure reading plugin [%v] stdout (read '%v')", bin, port)
}
if n > 0 && b[0] == '\n' {
break
}
port += string(b[:n])
}
// Parse the output line (minus the '\n') to ensure it's a numeric port.
if _, err = strconv.Atoi(port); err != nil {
killerr := plug.Proc.Kill()
contract.IgnoreError(killerr) // ignoring the error because the existing one trumps it.
return nil, errors.Wrapf(
err, "%v plugin [%v] wrote a non-numeric port to stdout ('%v')", prefix, bin, port)
}
// After reading the port number, set up a tracer on stdout just so other output doesn't disappear.
stdoutDone := make(chan bool)
plug.stdoutDone = stdoutDone
go runtrace(plug.Stdout, false, stdoutDone)
// Now that we have the port, go ahead and create a gRPC client connection to it.
conn, err := grpc.Dial("127.0.0.1:"+port, grpc.WithInsecure(), grpc.WithUnaryInterceptor(
rpcutil.OpenTracingClientInterceptor(),
))
if err != nil {
return nil, errors.Wrapf(err, "could not dial plugin [%v] over RPC", bin)
}
// Now wait for the gRPC connection to the plugin to become ready.
// TODO[pulumi/pulumi#337]: in theory, this should be unnecessary. gRPC's default WaitForReady behavior
// should auto-retry appropriately. On Linux, however, we are observing different behavior. In the meantime
// while this bug exists, we'll simply do a bit of waiting of our own up front.
timeout, _ := context.WithTimeout(context.Background(), pluginRPCConnectionTimeout)
for {
s := conn.GetState()
if s == connectivity.Ready {
// The connection is supposedly ready; but we will make sure it is *actually* ready by sending a dummy
// method invocation to the server. Until it responds successfully, we can't safely proceed.
outer:
for {
err = grpc.Invoke(timeout, "", nil, nil, conn)
if err == nil {
break // successful connect
} else {
// We have an error; see if it's a known status and, if so, react appropriately.
status, ok := status.FromError(err)
if ok {
switch status.Code() {
case codes.Unavailable:
// The server is unavailable. This is the Linux bug. Wait a little and retry.
time.Sleep(time.Millisecond * 10)
continue // keep retrying
case codes.Unimplemented, codes.ResourceExhausted:
// Since we sent "" as the method above, this is the expected response. Ready to go.
break outer
}
}
// Unexpected error; get outta dodge.
return nil, errors.Wrapf(err, "%v plugin [%v] did not come alive", prefix, bin)
}
}
break
}
// Not ready yet; ask the gRPC client APIs to block until the state transitions again so we can retry.
if !conn.WaitForStateChange(timeout, s) {
return nil, errors.Errorf("%v plugin [%v] did not begin responding to RPC connections", prefix, bin)
}
}
// Done; store the connection and return the plugin info.
plug.Conn = conn
return plug, nil
}
func execPlugin(bin string, pluginArgs []string, pwd string) (*plugin, error) {
var args []string
// Flow the logging information if set.
if logging.LogFlow {
if logging.LogToStderr {
args = append(args, "-logtostderr")
}
if logging.Verbose > 0 {
args = append(args, "-v="+strconv.Itoa(logging.Verbose))
}
}
// Always flow tracing settings.
if cmdutil.TracingEndpoint != "" {
args = append(args, "--tracing", cmdutil.TracingEndpoint)
}
args = append(args, pluginArgs...)
cmd := exec.Command(bin, args...)
cmdutil.RegisterProcessGroup(cmd)
cmd.Dir = pwd
in, _ := cmd.StdinPipe()
out, _ := cmd.StdoutPipe()
err, _ := cmd.StderrPipe()
if err := cmd.Start(); err != nil {
return nil, err
}
return &plugin{
Bin: bin,
Args: args,
Proc: cmd.Process,
Stdin: in,
Stdout: out,
Stderr: err,
}, nil
}
func (p *plugin) Close() error {
if p.Conn != nil {
closerr := p.Conn.Close()
contract.IgnoreError(closerr)
}
var result error
// On each platform, plugins are not loaded directly, instead a shell launches each plugin as a child process, so
// instead we need to kill all the children of the PID we have recorded, as well. Otherwise we will block waiting
// for the child processes to close.
if err := cmdutil.KillChildren(p.Proc.Pid); err != nil {
result = multierror.Append(result, err)
}
// IDEA: consider a more graceful termination than just SIGKILL.
if err := p.Proc.Kill(); err != nil {
result = multierror.Append(result, err)
}
// Wait for stdout and stderr to drain.
if p.stdoutDone != nil {
<-p.stdoutDone
}
if p.stderrDone != nil {
<-p.stderrDone
}
return result
}