github.com/looshlee/beatles@v0.0.0-20220727174639-742810ab631c/pkg/command/exec/exec.go (about)

     1  // Copyright 2018 Authors of Cilium
     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 exec
    16  
    17  import (
    18  	"bufio"
    19  	"bytes"
    20  	"context"
    21  	"fmt"
    22  	"os/exec"
    23  	"strings"
    24  	"time"
    25  
    26  	"github.com/sirupsen/logrus"
    27  )
    28  
    29  // combinedOutput is the core implementation of catching deadline exceeded
    30  // options and logging errors, with an optional set of filtered outputs.
    31  func combinedOutput(ctx context.Context, cmd *exec.Cmd, filters []string, scopedLog *logrus.Entry, verbose bool) ([]byte, error) {
    32  	out, err := cmd.CombinedOutput()
    33  	if ctx.Err() != nil {
    34  		scopedLog.WithError(err).WithField("cmd", cmd.Args).Error("Command execution failed")
    35  		return nil, fmt.Errorf("Command execution failed for %s: %s", cmd.Args, ctx.Err())
    36  	}
    37  	if err != nil {
    38  		if verbose {
    39  			scopedLog.WithError(err).WithField("cmd", cmd.Args).Error("Command execution failed")
    40  
    41  			scanner := bufio.NewScanner(bytes.NewReader(out))
    42  		scan:
    43  			for scanner.Scan() {
    44  				text := scanner.Text()
    45  				for _, filter := range filters {
    46  					if strings.Contains(text, filter) {
    47  						continue scan
    48  					}
    49  				}
    50  				scopedLog.Warn(text)
    51  			}
    52  		}
    53  	}
    54  	return out, err
    55  }
    56  
    57  // Cmd wraps exec.Cmd with a context to provide convenient execution of a
    58  // command with nice checking of the context timeout in the form:
    59  //
    60  // err := exec.Prog().WithTimeout(5*time.Second, myprog, myargs...).CombinedOutput(log, verbose)
    61  type Cmd struct {
    62  	*exec.Cmd
    63  	ctx      context.Context
    64  	cancelFn func()
    65  
    66  	// filters is a slice of strings that should be omitted from logging.
    67  	filters []string
    68  }
    69  
    70  // CommandContext wraps exec.CommandContext to allow this package to be used as
    71  // a drop-in replacement for the standard exec library.
    72  func CommandContext(ctx context.Context, prog string, args ...string) *Cmd {
    73  	return &Cmd{
    74  		Cmd: exec.CommandContext(ctx, prog, args...),
    75  		ctx: ctx,
    76  	}
    77  }
    78  
    79  // WithTimeout creates a Cmd with a context that times out after the specified
    80  // duration.
    81  func WithTimeout(timeout time.Duration, prog string, args ...string) *Cmd {
    82  	ctx, cancel := context.WithTimeout(context.Background(), timeout)
    83  	cmd := CommandContext(ctx, prog, args...)
    84  	cmd.cancelFn = cancel
    85  	return cmd
    86  }
    87  
    88  // WithCancel creates a Cmd with a context that can be cancelled by calling the
    89  // resulting Cancel() function.
    90  func WithCancel(ctx context.Context, prog string, args ...string) (*Cmd, context.CancelFunc) {
    91  	newCtx, cancel := context.WithCancel(ctx)
    92  	cmd := CommandContext(newCtx, prog, args...)
    93  	return cmd, cancel
    94  }
    95  
    96  // WithFilters modifies the specified command to filter any output lines from
    97  // logs if they contain any of the substrings specified as arguments to this
    98  // function.
    99  func (c *Cmd) WithFilters(filters ...string) *Cmd {
   100  	c.filters = append(c.filters, filters...)
   101  	return c
   102  }
   103  
   104  // CombinedOutput runs the command and returns its combined standard output and
   105  // standard error. Unlike the standard library, if the context is exceeded, it
   106  // will return an error indicating so.
   107  //
   108  // Logs any errors that occur to the specified logger.
   109  func (c *Cmd) CombinedOutput(scopedLog *logrus.Entry, verbose bool) ([]byte, error) {
   110  	out, err := combinedOutput(c.ctx, c.Cmd, c.filters, scopedLog, verbose)
   111  	if c.cancelFn != nil {
   112  		c.cancelFn()
   113  	}
   114  	return out, err
   115  }