From 9e772e931b1b2b2d27c6d2c4a03b133c745fc8ef Mon Sep 17 00:00:00 2001
From: Evan Bradley <11745660+evan-bradley@users.noreply.github.com>
Date: Wed, 15 Jan 2025 11:46:48 -0500
Subject: [PATCH 1/3] [service] Return telemetry.Config validation errors

---
 .chloggen/service-config-validate.yaml     | 25 ++++++++++++++++++++++
 otelcol/testdata/otelcol-emptyreaders.yaml |  1 +
 service/config.go                          |  2 +-
 3 files changed, 27 insertions(+), 1 deletion(-)
 create mode 100644 .chloggen/service-config-validate.yaml

diff --git a/.chloggen/service-config-validate.yaml b/.chloggen/service-config-validate.yaml
new file mode 100644
index 00000000000..7cb483d00f8
--- /dev/null
+++ b/.chloggen/service-config-validate.yaml
@@ -0,0 +1,25 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: bug_fix
+
+# The name of the component, or a single word describing the area of concern, (e.g. otlpreceiver)
+component: service
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Include validation errors from telemetry.Config when validating the service config
+
+# One or more tracking issues or pull requests related to the change
+issues: []
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext: Previously validation errors were only printed to the console
+
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: []
diff --git a/otelcol/testdata/otelcol-emptyreaders.yaml b/otelcol/testdata/otelcol-emptyreaders.yaml
index 3a71b541f1a..f8f78dc7ba6 100644
--- a/otelcol/testdata/otelcol-emptyreaders.yaml
+++ b/otelcol/testdata/otelcol-emptyreaders.yaml
@@ -7,6 +7,7 @@ exporters:
 service:
   telemetry:
     metrics:
+      level: none
       readers: []
   pipelines:
     metrics:
diff --git a/service/config.go b/service/config.go
index 9c3eb4d7d74..2cf2d26934d 100644
--- a/service/config.go
+++ b/service/config.go
@@ -29,7 +29,7 @@ func (cfg *Config) Validate() error {
 	}
 
 	if err := cfg.Telemetry.Validate(); err != nil {
-		fmt.Printf("service::telemetry config validation failed: %v\n", err)
+		return fmt.Errorf("service::telemetry config validation failed: %w", err)
 	}
 
 	return nil

From 92dfb4c9f96caf623506611d1c1c80fa4ab384d0 Mon Sep 17 00:00:00 2001
From: Evan Bradley <11745660+evan-bradley@users.noreply.github.com>
Date: Wed, 22 Jan 2025 10:09:08 -0500
Subject: [PATCH 2/3] Fix test

---
 service/config_test.go | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/service/config_test.go b/service/config_test.go
index ab292a2665d..f313b1aa318 100644
--- a/service/config_test.go
+++ b/service/config_test.go
@@ -71,14 +71,19 @@ func TestConfigValidate(t *testing.T) {
 				cfg.Telemetry.Metrics.Readers = nil
 				return cfg
 			},
-			expected: nil,
+			expected: errors.New("service::telemetry config validation failed: collector telemetry metrics reader should exist when metric level is not none"),
 		},
 	}
 
 	for _, tt := range testCases {
 		t.Run(tt.name, func(t *testing.T) {
 			cfg := tt.cfgFn()
-			assert.Equal(t, tt.expected, cfg.Validate())
+			err := cfg.Validate()
+			if tt.expected != nil {
+				assert.EqualError(t, err, tt.expected.Error())
+			} else {
+				assert.NoError(t, err)
+			}
 		})
 	}
 }

From c1b198046ca5c8cda8b9612aa9bb8533905a1a6f Mon Sep 17 00:00:00 2001
From: Evan Bradley <11745660+evan-bradley@users.noreply.github.com>
Date: Wed, 22 Jan 2025 11:41:32 -0500
Subject: [PATCH 3/3] Add issue number

---
 .chloggen/service-config-validate.yaml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.chloggen/service-config-validate.yaml b/.chloggen/service-config-validate.yaml
index 7cb483d00f8..03abd62cb71 100644
--- a/.chloggen/service-config-validate.yaml
+++ b/.chloggen/service-config-validate.yaml
@@ -10,7 +10,7 @@ component: service
 note: Include validation errors from telemetry.Config when validating the service config
 
 # One or more tracking issues or pull requests related to the change
-issues: []
+issues: [12100]
 
 # (Optional) One or more lines of additional information to render under the primary note.
 # These lines will be padded with 2 spaces and then inserted directly into the document.