1 files changed, 157 insertions, 0 deletions
diff --git a/src/go/collectors/go.d.plugin/agent/discovery/sd/pipeline/compose.go b/src/go/collectors/go.d.plugin/agent/discovery/sd/pipeline/compose.go
new file mode 100644
index 000000000..de2ed21b8
--- /dev/null
+++ b/src/go/collectors/go.d.plugin/agent/discovery/sd/pipeline/compose.go
@@ -0,0 +1,157 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+package pipeline
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"text/template"
+
+	"github.com/netdata/netdata/go/go.d.plugin/agent/confgroup"
+	"github.com/netdata/netdata/go/go.d.plugin/agent/discovery/sd/model"
+	"github.com/netdata/netdata/go/go.d.plugin/logger"
+
+	"gopkg.in/yaml.v2"
+)
+
+func newConfigComposer(cfg []ComposeRuleConfig) (*configComposer, error) {
+	rules, err := newComposeRules(cfg)
+	if err != nil {
+		return nil, err
+	}
+
+	c := &configComposer{
+		rules: rules,
+		buf:   bytes.Buffer{},
+	}
+
+	return c, nil
+}
+
+type (
+	configComposer struct {
+		*logger.Logger
+		rules []*composeRule
+		buf   bytes.Buffer
+	}
+
+	composeRule struct {
+		name string
+		sr   selector
+		conf []*composeRuleConf
+	}
+	composeRuleConf struct {
+		sr   selector
+		tmpl *template.Template
+	}
+)
+
+func (c *configComposer) compose(tgt model.Target) []confgroup.Config {
+	var configs []confgroup.Config
+
+	for i, rule := range c.rules {
+		if !rule.sr.matches(tgt.Tags()) {
+			continue
+		}
+
+		for j, conf := range rule.conf {
+			if !conf.sr.matches(tgt.Tags()) {
+				continue
+			}
+
+			c.buf.Reset()
+
+			if err := conf.tmpl.Execute(&c.buf, tgt); err != nil {
+				c.Warningf("failed to execute rule[%d]->config[%d]->template on target '%s': %v",
+					i+1, j+1, tgt.TUID(), err)
+				continue
+			}
+			if c.buf.Len() == 0 {
+				continue
+			}
+
+			cfgs, err := c.parseTemplateData(c.buf.Bytes())
+			if err != nil {
+				c.Warningf("failed to parse template data: %v", err)
+				continue
+			}
+
+			configs = append(configs, cfgs...)
+		}
+	}
+
+	if len(configs) > 0 {
+		c.Debugf("created %d config(s) for target '%s'", len(configs), tgt.TUID())
+	}
+	return configs
+}
+
+func (c *configComposer) parseTemplateData(bs []byte) ([]confgroup.Config, error) {
+	var data any
+	if err := yaml.Unmarshal(bs, &data); err != nil {
+		return nil, err
+	}
+
+	type (
+		single = map[any]any
+		multi  = []any
+	)
+
+	switch data.(type) {
+	case single:
+		var cfg confgroup.Config
+		if err := yaml.Unmarshal(bs, &cfg); err != nil {
+			return nil, err
+		}
+		return []confgroup.Config{cfg}, nil
+	case multi:
+		var cfgs []confgroup.Config
+		if err := yaml.Unmarshal(bs, &cfgs); err != nil {
+			return nil, err
+		}
+		return cfgs, nil
+	default:
+		return nil, errors.New("unknown config format")
+	}
+}
+
+func newComposeRules(cfg []ComposeRuleConfig) ([]*composeRule, error) {
+	var rules []*composeRule
+
+	fmap := newFuncMap()
+
+	for i, ruleCfg := range cfg {
+		i++
+		rule := composeRule{name: ruleCfg.Name}
+
+		sr, err := parseSelector(ruleCfg.Selector)
+		if err != nil {
+			return nil, fmt.Errorf("rule '%d': %v", i, err)
+		}
+		rule.sr = sr
+
+		for j, confCfg := range ruleCfg.Config {
+			j++
+			var conf composeRuleConf
+
+			sr, err := parseSelector(confCfg.Selector)
+			if err != nil {
+				return nil, fmt.Errorf("rule '%d/%d': %v", i, j, err)
+			}
+			conf.sr = sr
+
+			tmpl, err := parseTemplate(confCfg.Template, fmap)
+			if err != nil {
+				return nil, fmt.Errorf("rule '%d/%d': %v", i, j, err)
+			}
+			conf.tmpl = tmpl
+
+			rule.conf = append(rule.conf, &conf)
+		}
+
+		rules = append(rules, &rule)
+	}
+
+	return rules, nil
+}