From 3328b40c0ffe33b2c23e15398e7564b48dfb401c Mon Sep 17 00:00:00 2001
From: Gregor Zeitlinger <gregor.zeitlinger@grafana.com>
Date: Fri, 19 Jan 2024 12:09:17 +0100
Subject: [PATCH] header values are be expected to be W3C baggage encoded

---
 .../java/io/micrometer/registry/otlp/OtlpConfig.java   |  6 +++---
 .../io/micrometer/registry/otlp/OtlpConfigTest.java    | 10 ++++++++++
 2 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/implementations/micrometer-registry-otlp/src/main/java/io/micrometer/registry/otlp/OtlpConfig.java b/implementations/micrometer-registry-otlp/src/main/java/io/micrometer/registry/otlp/OtlpConfig.java
index ec20dbadbd..d6910e5a53 100644
--- a/implementations/micrometer-registry-otlp/src/main/java/io/micrometer/registry/otlp/OtlpConfig.java
+++ b/implementations/micrometer-registry-otlp/src/main/java/io/micrometer/registry/otlp/OtlpConfig.java
@@ -18,7 +18,6 @@
 import io.micrometer.core.instrument.config.validate.Validated;
 import io.micrometer.core.instrument.push.PushRegistryConfig;
 
-import java.io.UnsupportedEncodingException;
 import java.net.URLDecoder;
 import java.util.Arrays;
 import java.util.Map;
@@ -137,8 +136,9 @@ default Map<String, String> headers() {
                 // headers are encoded as URL - see
                 // https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/protocol/exporter.md#specifying-headers-via-environment-variables
                 headersString = URLDecoder.decode(headersString, "UTF-8");
-            } catch (UnsupportedEncodingException e) {
-                throw new IllegalArgumentException("cannot decode header value: " + headersString, e);
+            }
+            catch (Exception e) {
+                throw new IllegalArgumentException("Cannot decode header value: " + headersString, e);
             }
         }
 
diff --git a/implementations/micrometer-registry-otlp/src/test/java/io/micrometer/registry/otlp/OtlpConfigTest.java b/implementations/micrometer-registry-otlp/src/test/java/io/micrometer/registry/otlp/OtlpConfigTest.java
index 77c4928740..a3c52f2fe0 100644
--- a/implementations/micrometer-registry-otlp/src/test/java/io/micrometer/registry/otlp/OtlpConfigTest.java
+++ b/implementations/micrometer-registry-otlp/src/test/java/io/micrometer/registry/otlp/OtlpConfigTest.java
@@ -23,6 +23,7 @@
 import java.util.stream.Stream;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
 import static uk.org.webcompere.systemstubs.SystemStubs.withEnvironmentVariable;
 import static uk.org.webcompere.systemstubs.SystemStubs.withEnvironmentVariables;
 
@@ -66,6 +67,15 @@ void headersUseEnvVarWhenConfigNotSet() throws Exception {
             .execute(() -> assertThat(config.headers()).containsEntry("header2", "va lue").hasSize(1));
     }
 
+    @Test
+    void headersDecodingError() throws Exception {
+        OtlpConfig config = k -> null;
+        withEnvironmentVariable("OTEL_EXPORTER_OTLP_HEADERS", "header2=%-1").execute(() -> {
+            assertThatThrownBy(config::headers).isInstanceOf(IllegalArgumentException.class)
+                .hasMessage("Cannot decode header value: header2=%-1,");
+        });
+    }
+
     @Test
     void combineHeadersFromEnvVars() throws Exception {
         OtlpConfig config = k -> null;