github.com/grafana/tanka@v0.26.1-0.20240506093700-c22cfc35c21a/pkg/kubernetes/client/kubectl.go (about)

     1  package client
     2  
     3  import (
     4  	"bytes"
     5  	"encoding/json"
     6  	"fmt"
     7  	"os"
     8  	"regexp"
     9  
    10  	"github.com/pkg/errors"
    11  
    12  	"github.com/grafana/tanka/pkg/kubernetes/manifest"
    13  )
    14  
    15  // Kubectl uses the `kubectl` command to operate on a Kubernetes cluster
    16  type Kubectl struct {
    17  	info Info
    18  }
    19  
    20  // New returns a instance of Kubectl with a correct context already discovered.
    21  func New(endpoint string) (*Kubectl, error) {
    22  	k := Kubectl{}
    23  
    24  	// discover context
    25  	var err error
    26  	k.info.Kubeconfig, err = findContextFromEndpoint(endpoint)
    27  	if err != nil {
    28  		return nil, errors.Wrap(err, "finding usable context")
    29  	}
    30  
    31  	// query versions (requires context)
    32  	k.info.ClientVersion, k.info.ServerVersion, err = k.version()
    33  	if err != nil {
    34  		return nil, errors.Wrap(err, "obtaining versions")
    35  	}
    36  
    37  	return &k, nil
    38  }
    39  
    40  func NewFromNames(names []string) (*Kubectl, error) {
    41  	k := Kubectl{}
    42  
    43  	var err error
    44  	k.info.Kubeconfig, err = findContextFromNames(names)
    45  	if err != nil {
    46  		return nil, errors.Wrap(err, "finding usable context")
    47  	}
    48  
    49  	// query versions (requires context)
    50  	k.info.ClientVersion, k.info.ServerVersion, err = k.version()
    51  	if err != nil {
    52  		return nil, errors.Wrap(err, "obtaining versions")
    53  	}
    54  
    55  	return &k, nil
    56  }
    57  
    58  // Info returns known informational data about the client and its environment
    59  func (k Kubectl) Info() Info {
    60  	return k.info
    61  }
    62  
    63  // Close runs final cleanup:
    64  func (k Kubectl) Close() error {
    65  	return nil
    66  }
    67  
    68  // Namespaces of the cluster
    69  func (k Kubectl) Namespaces() (map[string]bool, error) {
    70  	cmd := k.ctl("get", "namespaces", "-o", "json")
    71  
    72  	var sout bytes.Buffer
    73  	var serr bytes.Buffer
    74  	cmd.Stdout = &sout
    75  	cmd.Stderr = &serr
    76  
    77  	err := cmd.Run()
    78  	if err != nil {
    79  		return nil, errors.Wrap(err, serr.String())
    80  	}
    81  
    82  	var list manifest.Manifest
    83  	if err := json.Unmarshal(sout.Bytes(), &list); err != nil {
    84  		return nil, err
    85  	}
    86  
    87  	items, err := list.Items()
    88  	if err != nil {
    89  		return nil, err
    90  	}
    91  
    92  	namespaces := make(map[string]bool)
    93  	for _, m := range items {
    94  		namespaces[m.Metadata().Name()] = true
    95  	}
    96  	return namespaces, nil
    97  }
    98  
    99  type ErrNamespaceNotFound struct {
   100  	Namespace string
   101  }
   102  
   103  func (e ErrNamespaceNotFound) Error() string {
   104  	return fmt.Sprintf("Namespace not found: %s", e.Namespace)
   105  }
   106  
   107  // Namespace finds a single namespace in the cluster
   108  func (k Kubectl) Namespace(namespace string) (manifest.Manifest, error) {
   109  	cmd := k.ctl("get", "namespaces", namespace, "-o", "json", "--ignore-not-found")
   110  
   111  	var sout bytes.Buffer
   112  	cmd.Stdout = &sout
   113  	cmd.Stderr = os.Stderr
   114  
   115  	err := cmd.Run()
   116  	if err != nil {
   117  		return nil, err
   118  	}
   119  	if len(sout.Bytes()) == 0 {
   120  		return nil, ErrNamespaceNotFound{
   121  			Namespace: namespace,
   122  		}
   123  	}
   124  	var ns manifest.Manifest
   125  	if err := json.Unmarshal(sout.Bytes(), &ns); err != nil {
   126  		return nil, err
   127  	}
   128  	return ns, nil
   129  }
   130  
   131  // FilterWriter is an io.Writer that discards every message that matches at
   132  // least one of the regular expressions.
   133  type FilterWriter struct {
   134  	buf     string
   135  	filters []*regexp.Regexp
   136  }
   137  
   138  func (r *FilterWriter) Write(p []byte) (n int, err error) {
   139  	for _, re := range r.filters {
   140  		if re.Match(p) {
   141  			// silently discard
   142  			return len(p), nil
   143  		}
   144  	}
   145  	r.buf += string(p)
   146  	return os.Stderr.Write(p)
   147  }