Add support for the config file (#254)

README.md

@@ -69,38 +69,39 @@ Supported Kubernetes resources are `pod`, `replicationcontroller`, `service`, `d
 ### cli flags
 
 <!-- auto generated cli flags begin --->
- flag                        | default   | purpose
------------------------------|-----------|---------
- `--all-namespaces`, `-A`    | `false`   | If present, tail across all namespaces. A specific namespace is ignored even if specified with --namespace.
- `--color`                   | `auto`    | Force set color output. 'auto':  colorize if tty attached, 'always': always colorize, 'never': never colorize.
- `--completion`              |           | Output stern command-line completion code for the specified shell. Can be 'bash', 'zsh' or 'fish'.
- `--container`, `-c`         | `.*`      | Container name when multiple containers in pod. (regular expression)
- `--container-state`         | `all`     | Tail containers with state in running, waiting, terminated, or all. 'all' matches all container states. To specify multiple states, repeat this or set comma-separated value.
- `--context`                 |           | Kubernetes context to use. Default to current context configured in kubeconfig.
- `--ephemeral-containers`    | `true`    | Include or exclude ephemeral containers.
- `--exclude`, `-e`           | `[]`      | Log lines to exclude. (regular expression)
- `--exclude-container`, `-E` | `[]`      | Container name to exclude when multiple containers in pod. (regular expression)
- `--exclude-pod`             | `[]`      | Pod name to exclude. (regular expression)
- `--field-selector`          |           | Selector (field query) to filter on. If present, default to ".*" for the pod-query.
- `--include`, `-i`           | `[]`      | Log lines to include. (regular expression)
- `--init-containers`         | `true`    | Include or exclude init containers.
- `--kubeconfig`              |           | Path to kubeconfig file to use. Default to KUBECONFIG variable then ~/.kube/config path.
- `--max-log-requests`        | `-1`      | Maximum number of concurrent logs to request. Defaults to 50, but 5 when specifying --no-follow
- `--namespace`, `-n`         |           | Kubernetes namespace to use. Default to namespace configured in kubernetes context. To specify multiple namespaces, repeat this or set comma-separated value.
- `--no-follow`               | `false`   | Exit when all logs have been shown.
- `--node`                    |           | Node name to filter on.
- `--only-log-lines`          | `false`   | Print only log lines
- `--output`, `-o`            | `default` | Specify predefined template. Currently support: [default, raw, json, extjson, ppextjson]
- `--prompt`, `-p`            | `false`   | Toggle interactive prompt for selecting 'app.kubernetes.io/instance' label values.
- `--selector`, `-l`          |           | Selector (label query) to filter on. If present, default to ".*" for the pod-query.
- `--since`, `-s`             | `48h0m0s` | Return logs newer than a relative duration like 5s, 2m, or 3h.
- `--tail`                    | `-1`      | The number of lines from the end of the logs to show. Defaults to -1, showing all logs.
- `--template`                |           | Template to use for log lines, leave empty to use --output flag.
- `--template-file`, `-T`     |           | Path to template to use for log lines, leave empty to use --output flag. It overrides --template option.
- `--timestamps`, `-t`        |           | Print timestamps with the specified format. One of 'default' or 'short'. If specified but without value, 'default' is used.
- `--timezone`                | `Local`   | Set timestamps to specific timezone.
- `--verbosity`               | `0`       | Number of the log level verbosity
- `--version`, `-v`           | `false`   | Print the version and exit.
+ flag                        | default                       | purpose
+-----------------------------|-------------------------------|---------
+ `--all-namespaces`, `-A`    | `false`                       | If present, tail across all namespaces. A specific namespace is ignored even if specified with --namespace.
+ `--color`                   | `auto`                        | Force set color output. 'auto':  colorize if tty attached, 'always': always colorize, 'never': never colorize.
+ `--completion`              |                               | Output stern command-line completion code for the specified shell. Can be 'bash', 'zsh' or 'fish'.
+ `--config`                  | `~/.config/stern/config.yaml` | Path to the stern config file
+ `--container`, `-c`         | `.*`                          | Container name when multiple containers in pod. (regular expression)
+ `--container-state`         | `all`                         | Tail containers with state in running, waiting, terminated, or all. 'all' matches all container states. To specify multiple states, repeat this or set comma-separated value.
+ `--context`                 |                               | Kubernetes context to use. Default to current context configured in kubeconfig.
+ `--ephemeral-containers`    | `true`                        | Include or exclude ephemeral containers.
+ `--exclude`, `-e`           | `[]`                          | Log lines to exclude. (regular expression)
+ `--exclude-container`, `-E` | `[]`                          | Container name to exclude when multiple containers in pod. (regular expression)
+ `--exclude-pod`             | `[]`                          | Pod name to exclude. (regular expression)
+ `--field-selector`          |                               | Selector (field query) to filter on. If present, default to ".*" for the pod-query.
+ `--include`, `-i`           | `[]`                          | Log lines to include. (regular expression)
+ `--init-containers`         | `true`                        | Include or exclude init containers.
+ `--kubeconfig`              |                               | Path to kubeconfig file to use. Default to KUBECONFIG variable then ~/.kube/config path.
+ `--max-log-requests`        | `-1`                          | Maximum number of concurrent logs to request. Defaults to 50, but 5 when specifying --no-follow
+ `--namespace`, `-n`         |                               | Kubernetes namespace to use. Default to namespace configured in kubernetes context. To specify multiple namespaces, repeat this or set comma-separated value.
+ `--no-follow`               | `false`                       | Exit when all logs have been shown.
+ `--node`                    |                               | Node name to filter on.
+ `--only-log-lines`          | `false`                       | Print only log lines
+ `--output`, `-o`            | `default`                     | Specify predefined template. Currently support: [default, raw, json, extjson, ppextjson]
+ `--prompt`, `-p`            | `false`                       | Toggle interactive prompt for selecting 'app.kubernetes.io/instance' label values.
+ `--selector`, `-l`          |                               | Selector (label query) to filter on. If present, default to ".*" for the pod-query.
+ `--since`, `-s`             | `48h0m0s`                     | Return logs newer than a relative duration like 5s, 2m, or 3h.
+ `--tail`                    | `-1`                          | The number of lines from the end of the logs to show. Defaults to -1, showing all logs.
+ `--template`                |                               | Template to use for log lines, leave empty to use --output flag.
+ `--template-file`, `-T`     |                               | Path to template to use for log lines, leave empty to use --output flag. It overrides --template option.
+ `--timestamps`, `-t`        |                               | Print timestamps with the specified format. One of 'default' or 'short'. If specified but without value, 'default' is used.
+ `--timezone`                | `Local`                       | Set timestamps to specific timezone.
+ `--verbosity`               | `0`                           | Number of the log level verbosity
+ `--version`, `-v`           | `false`                       | Print the version and exit.
 <!-- auto generated cli flags end --->
 
 See `stern --help` for details
@@ -109,6 +110,19 @@ Stern will use the `$KUBECONFIG` environment variable if set. If both the
 environment variable and `--kubeconfig` flag are passed the cli flag will be
 used.
 
+## config file
+
+You can use the config file to change the default values of stern options. The default config file path is `~/.config/stern/config.yaml`. 
+
+```yaml
+# <flag name>: <value>
+tail: 10
+max-log-requests: 999
+timestamps: short
+```
+
+You can change the config file path with `--config` flag or `STERNCONFIG` environment variable.
+
 ### templates
 
 stern supports outputting custom log messages.  There are a few predefined

cmd/cmd.go

@@ -26,19 +26,23 @@ import (
 	"text/template"
 	"time"
 
-	"k8s.io/klog/v2"
-
 	"github.com/fatih/color"
+	"github.com/mitchellh/go-homedir"
 	"github.com/pkg/errors"
 	"github.com/spf13/cast"
 	"github.com/spf13/cobra"
 	"github.com/spf13/pflag"
 	"github.com/stern/stern/stern"
+	"gopkg.in/yaml.v3"
 	"k8s.io/apimachinery/pkg/fields"
 	"k8s.io/apimachinery/pkg/labels"
 	"k8s.io/cli-runtime/pkg/genericclioptions"
+	"k8s.io/klog/v2"
 )
 
+// Use "~" to avoid exposing the user name in the help message
+var defaultConfigFilePath = "~/.config/stern/config.yaml"
+
 type options struct {
 	genericclioptions.IOStreams
 
@@ -74,6 +78,7 @@ type options struct {
 	onlyLogLines        bool
 	maxLogRequests      int
 	node                string
+	configFilePath      string
 }
 
 func NewOptions(streams genericclioptions.IOStreams) *options {
@@ -95,6 +100,7 @@ func NewOptions(streams genericclioptions.IOStreams) *options {
 		prompt:              false,
 		noFollow:            false,
 		maxLogRequests:      -1,
+		configFilePath:      defaultConfigFilePath,
 	}
 }
 
@@ -107,6 +113,11 @@ func (o *options) Complete(args []string) error {
 		}
 	}
 
+	envVar, ok := os.LookupEnv("STERNCONFIG")
+	if ok {
+		o.configFilePath = envVar
+	}
+
 	return nil
 }
 
@@ -289,6 +300,54 @@ func (o *options) setVerbosity() error {
 	return nil
 }
 
+// overrideFlagSetDefaultFromConfig overrides the default value of the flagSets
+// from the config file
+func (o *options) overrideFlagSetDefaultFromConfig(fs *pflag.FlagSet) error {
+	expanded, err := homedir.Expand(o.configFilePath)
+	if err != nil {
+		return err
+	}
+
+	if o.configFilePath == defaultConfigFilePath {
+		if _, err := os.Stat(expanded); os.IsNotExist(err) {
+			return nil
+		}
+	}
+
+	configFile, err := os.Open(expanded)
+	if err != nil {
+		return err
+	}
+
+	data := make(map[string]interface{})
+
+	if err := yaml.NewDecoder(configFile).Decode(data); err != nil {
+		return err
+	}
+
+	for name, value := range data {
+		flag := fs.Lookup(name)
+		if flag == nil {
+			// To avoid command execution failure, we only output a warning
+			// message instead of exiting with an error if an unknown option is
+			// specified.
+			klog.Warningf("Unknown option specified in the config file: %s", name)
+			continue
+		}
+
+		// flag has higher priority than the config file
+		if flag.Changed {
+			continue
+		}
+
+		if err := flag.Value.Set(fmt.Sprint(value)); err != nil {
+			return fmt.Errorf("invalid value %q for %q in the config file: %v", value, name, err)
+		}
+	}
+
+	return nil
+}
+
 // AddFlags adds all the flags used by stern.
 func (o *options) AddFlags(fs *pflag.FlagSet) {
 	fs.BoolVarP(&o.allNamespaces, "all-namespaces", "A", o.allNamespaces, "If present, tail across all namespaces. A specific namespace is ignored even if specified with --namespace.")
@@ -321,6 +380,7 @@ func (o *options) AddFlags(fs *pflag.FlagSet) {
 	fs.StringVarP(&o.timestamps, "timestamps", "t", o.timestamps, "Print timestamps with the specified format. One of 'default' or 'short'. If specified but without value, 'default' is used.")
 	fs.StringVar(&o.timezone, "timezone", o.timezone, "Set timestamps to specific timezone.")
 	fs.BoolVar(&o.onlyLogLines, "only-log-lines", o.onlyLogLines, "Print only log lines")
+	fs.StringVar(&o.configFilePath, "config", o.configFilePath, "Path to the stern config file")
 	fs.IntVar(&o.verbosity, "verbosity", o.verbosity, "Number of the log level verbosity")
 	fs.BoolVarP(&o.version, "version", "v", o.version, "Print the version and exit.")
 
@@ -486,6 +546,10 @@ func NewSternCmd(stream genericclioptions.IOStreams) (*cobra.Command, error) {
 				return err
 			}
 
+			if err := o.overrideFlagSetDefaultFromConfig(cmd.Flags()); err != nil {
+				return err
+			}
+
 			if err := o.Validate(); err != nil {
 				return err
 			}

cmd/cmd_test.go

@@ -2,13 +2,16 @@ package cmd
 
 import (
 	"bytes"
+	"os"
+	"path/filepath"
 	"reflect"
 	"regexp"
 	"strings"
 	"testing"
 	"time"
 
 	"github.com/fatih/color"
+	"github.com/spf13/pflag"
 	"github.com/stern/stern/stern"
 	"k8s.io/apimachinery/pkg/fields"
 	"k8s.io/apimachinery/pkg/labels"
@@ -54,6 +57,47 @@ func TestSternCommand(t *testing.T) {
 	}
 }
 
+func TestOptionsComplete(t *testing.T) {
+	streams := genericclioptions.NewTestIOStreamsDiscard()
+
+	tests := []struct {
+		name                   string
+		env                    map[string]string
+		args                   []string
+		expectedConfigFilePath string
+	}{
+		{
+			name:                   "No environment variables",
+			env:                    map[string]string{},
+			args:                   []string{},
+			expectedConfigFilePath: defaultConfigFilePath,
+		},
+		{
+			name: "Set STERNCONFIG env to ./config.yaml",
+			env: map[string]string{
+				"STERNCONFIG": "./config.yaml",
+			},
+			args:                   []string{},
+			expectedConfigFilePath: "./config.yaml",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			for k, v := range tt.env {
+				t.Setenv(k, v)
+			}
+
+			o := NewOptions(streams)
+			_ = o.Complete(tt.args)
+
+			if tt.expectedConfigFilePath != o.configFilePath {
+				t.Errorf("expected %s for configFilePath, but got %s", tt.expectedConfigFilePath, o.configFilePath)
+			}
+		})
+	}
+}
+
 func TestOptionsValidate(t *testing.T) {
 	streams := genericclioptions.NewTestIOStreamsDiscard()
 
@@ -745,3 +789,97 @@ func TestOptionsSternConfig(t *testing.T) {
 		})
 	}
 }
+
+func TestOptionsOverrideFlagSetDefaultFromConfig(t *testing.T) {
+	orig := defaultConfigFilePath
+	defer func() {
+		defaultConfigFilePath = orig
+	}()
+
+	defaultConfigFilePath = "./config.yaml"
+	wd, _ := os.Getwd()
+
+	tests := []struct {
+		name                    string
+		flagConfigFilePathValue string
+		flagTailValue           string
+		expectedTailValue       int64
+		wantErr                 bool
+	}{
+		{
+			name:                    "--config=testdata/config-tail1.yaml",
+			flagConfigFilePathValue: filepath.Join(wd, "testdata/config-tail1.yaml"),
+			expectedTailValue:       1,
+			wantErr:                 false,
+		},
+		{
+			name:                    "--config=config-not-exist.yaml",
+			flagConfigFilePathValue: filepath.Join(wd, "config-not-exist.yaml"),
+			wantErr:                 true,
+		},
+		{
+			name:                    "--config=config-invalid.yaml",
+			flagConfigFilePathValue: filepath.Join(wd, "testdata/config-invalid.yaml"),
+			wantErr:                 true,
+		},
+		{
+			name:                    "--config=config-unknown-option.yaml",
+			flagConfigFilePathValue: filepath.Join(wd, "testdata/config-unknown-option.yaml"),
+			expectedTailValue:       1,
+			wantErr:                 false,
+		},
+		{
+			name:                    "--config=config-tail-invalid-value.yaml",
+			flagConfigFilePathValue: filepath.Join(wd, "testdata/config-tail-invalid-value.yaml"),
+			wantErr:                 true,
+		},
+		{
+			name:              "config file path is not specified and config file does not exist",
+			expectedTailValue: -1,
+			wantErr:           false,
+		},
+		{
+			name:                    "--config=testdata/config-tail1.yaml and --tail=2",
+			flagConfigFilePathValue: filepath.Join(wd, "testdata/config-tail1.yaml"),
+			flagTailValue:           "2",
+			expectedTailValue:       2,
+			wantErr:                 false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			o := NewOptions(genericclioptions.NewTestIOStreamsDiscard())
+			fs := pflag.NewFlagSet("", pflag.ExitOnError)
+			o.AddFlags(fs)
+
+			args := []string{}
+			if tt.flagConfigFilePathValue != "" {
+				args = append(args, "--config="+tt.flagConfigFilePathValue)
+			}
+			if tt.flagTailValue != "" {
+				args = append(args, "--tail="+tt.flagTailValue)
+			}
+
+			if err := fs.Parse(args); err != nil {
+				t.Fatal(err)
+			}
+
+			err := o.overrideFlagSetDefaultFromConfig(fs)
+			if tt.wantErr {
+				if err == nil {
+					t.Error("expected err, but got nil")
+				}
+				return
+			}
+
+			if err != nil {
+				t.Errorf("unexpected err: %v", err)
+			}
+
+			if tt.expectedTailValue != o.tail {
+				t.Errorf("expected %d for tail, but got %d", tt.expectedTailValue, o.tail)
+			}
+		})
+	}
+}

cmd/testdata/config-invalid.yaml

@@ -0,0 +1 @@
+this is invalid config file

cmd/testdata/config-tail-invalid-value.yaml

@@ -0,0 +1 @@
+tail: invalid

cmd/testdata/config-tail1.yaml

@@ -0,0 +1 @@
+tail: 1

cmd/testdata/config-unknown-option.yaml

@@ -0,0 +1,2 @@
+unknown: 999
+tail: 1