template_render.go

Documentation: github.com/prometheus/alertmanager/cli

     1  // Copyright 2021 Prometheus Team
     2  // Licensed under the Apache License, Version 2.0 (the "License");
     3  // you may not use this file except in compliance with the License.
     4  // You may obtain a copy of the License at
     5  //
     6  // http://www.apache.org/licenses/LICENSE-2.0
     7  //
     8  // Unless required by applicable law or agreed to in writing, software
     9  // distributed under the License is distributed on an "AS IS" BASIS,
    10  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    11  // See the License for the specific language governing permissions and
    12  // limitations under the License.
    13  
    14  package cli
    15  
    16  import (
    17  	"context"
    18  	"encoding/json"
    19  	"fmt"
    20  	"io"
    21  	"os"
    22  	"time"
    23  
    24  	"gopkg.in/alecthomas/kingpin.v2"
    25  
    26  	"github.com/prometheus/alertmanager/template"
    27  )
    28  
    29  var defaultData = template.Data{
    30  	Receiver: "receiver",
    31  	Status:   "alertstatus",
    32  	Alerts: template.Alerts{
    33  		template.Alert{
    34  			Status: "alertstatus",
    35  			Labels: template.KV{
    36  				"label1":          "value1",
    37  				"label2":          "value2",
    38  				"instance":        "foo.bar:1234",
    39  				"commonlabelkey1": "commonlabelvalue1",
    40  				"commonlabelkey2": "commonlabelvalue2",
    41  			},
    42  			Annotations: template.KV{
    43  				"annotation1":          "value1",
    44  				"annotation2":          "value2",
    45  				"commonannotationkey1": "commonannotationvalue1",
    46  				"commonannotationkey2": "commonannotationvalue2",
    47  			},
    48  			StartsAt:     time.Now().Add(-5 * time.Minute),
    49  			EndsAt:       time.Now(),
    50  			GeneratorURL: "https://generatorurl.com",
    51  			Fingerprint:  "fingerprint1",
    52  		},
    53  		template.Alert{
    54  			Status: "alertstatus",
    55  			Labels: template.KV{
    56  				"foo":             "bar",
    57  				"baz":             "qux",
    58  				"commonlabelkey1": "commonlabelvalue1",
    59  				"commonlabelkey2": "commonlabelvalue2",
    60  			},
    61  			Annotations: template.KV{
    62  				"aaa":                  "bbb",
    63  				"ccc":                  "ddd",
    64  				"commonannotationkey1": "commonannotationvalue1",
    65  				"commonannotationkey2": "commonannotationvalue2",
    66  			},
    67  			StartsAt:     time.Now().Add(-10 * time.Minute),
    68  			EndsAt:       time.Now(),
    69  			GeneratorURL: "https://generatorurl.com",
    70  			Fingerprint:  "fingerprint2",
    71  		},
    72  	},
    73  	GroupLabels: template.KV{
    74  		"grouplabelkey1": "grouplabelvalue1",
    75  		"grouplabelkey2": "grouplabelvalue2",
    76  	},
    77  	CommonLabels: template.KV{
    78  		"commonlabelkey1": "commonlabelvalue1",
    79  		"commonlabelkey2": "commonlabelvalue2",
    80  	},
    81  	CommonAnnotations: template.KV{
    82  		"commonannotationkey1": "commonannotationvalue1",
    83  		"commonannotationkey2": "commonannotationvalue2",
    84  	},
    85  	ExternalURL: "https://example.com",
    86  }
    87  
    88  type templateRenderCmd struct {
    89  	templateFilesGlobs []string
    90  	templateType       string
    91  	templateText       string
    92  	templateData       *os.File
    93  }
    94  
    95  func configureTemplateRenderCmd(cc *kingpin.CmdClause) {
    96  	var (
    97  		c         = &templateRenderCmd{}
    98  		renderCmd = cc.Command("render", "Render a given definition in a template file to standard output.")
    99  	)
   100  
   101  	renderCmd.Flag("template.glob", "Glob of paths that will be expanded and used for rendering.").Required().StringsVar(&c.templateFilesGlobs)
   102  	renderCmd.Flag("template.text", "The template that will be rendered.").Required().StringVar(&c.templateText)
   103  	renderCmd.Flag("template.type", "The type of the template. Can be either text (default) or html.").EnumVar(&c.templateType, "html", "text")
   104  	renderCmd.Flag("template.data", "Full path to a file which contains the data of the alert(-s) with which the --template.text will be rendered. Must be in JSON. File must be formatted according to the following layout: https://pkg.go.dev/github.com/prometheus/alertmanager/template#Data. If none has been specified then a predefined, simple alert will be used for rendering.").FileVar(&c.templateData)
   105  
   106  	renderCmd.Action(execWithTimeout(c.render))
   107  }
   108  
   109  func (c *templateRenderCmd) render(ctx context.Context, _ *kingpin.ParseContext) error {
   110  	tmpl, err := template.FromGlobs(c.templateFilesGlobs...)
   111  	if err != nil {
   112  		return err
   113  	}
   114  
   115  	f := tmpl.ExecuteTextString
   116  	if c.templateType == "html" {
   117  		f = tmpl.ExecuteHTMLString
   118  	}
   119  
   120  	var data template.Data
   121  	if c.templateData == nil {
   122  		data = defaultData
   123  	} else {
   124  		content, err := io.ReadAll(c.templateData)
   125  		if err != nil {
   126  			return err
   127  		}
   128  		if err := json.Unmarshal(content, &data); err != nil {
   129  			return err
   130  		}
   131  	}
   132  
   133  	rendered, err := f(c.templateText, data)
   134  	if err != nil {
   135  		return err
   136  	}
   137  
   138  	fmt.Print(rendered)
   139  	return nil
   140  }
   141
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