github.com/google/cloudprober@v0.11.3/servers/external/external.go (about)

     1  // Copyright 2020 The Cloudprober Authors.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //      http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  // Package external adds support for an external server.
    16  package external
    17  
    18  import (
    19  	"context"
    20  	"fmt"
    21  	"os/exec"
    22  
    23  	"github.com/google/cloudprober/logger"
    24  	"github.com/google/cloudprober/metrics"
    25  	configpb "github.com/google/cloudprober/servers/external/proto"
    26  	"github.com/google/shlex"
    27  )
    28  
    29  // Server implements a external command runner.
    30  type Server struct {
    31  	c *configpb.ServerConf
    32  	l *logger.Logger
    33  
    34  	cmdName string
    35  	cmdArgs []string
    36  	cmd     *exec.Cmd
    37  }
    38  
    39  // TODO
    40  //	1. Export health status (pid-file OR by monitoring the process started.)
    41  //	2. Add support for command-line substitution.
    42  //  2. Add auto-restart support.
    43  
    44  // New creates a new external server.
    45  func New(initCtx context.Context, c *configpb.ServerConf, l *logger.Logger) (*Server, error) {
    46  	cmdParts, err := shlex.Split(c.GetCommand())
    47  	if err != nil {
    48  		return nil, fmt.Errorf("error parsing command line (%s): %v", c.GetCommand(), err)
    49  	}
    50  
    51  	return &Server{
    52  		c:       c,
    53  		l:       l,
    54  		cmdName: cmdParts[0],
    55  		cmdArgs: cmdParts[1:len(cmdParts)],
    56  	}, nil
    57  }
    58  
    59  // Start runs the external command.
    60  func (s *Server) Start(ctx context.Context, dataChan chan<- *metrics.EventMetrics) error {
    61  	s.cmd = exec.CommandContext(ctx, s.cmdName, s.cmdArgs...)
    62  	go func() {
    63  		err := s.cmd.Run()
    64  		s.l.Infof("Command %s started. Err status: %v", s.c.GetCommand(), err)
    65  	}()
    66  
    67  	return nil
    68  }