URL decode headers from environment variables in OtlpConfig (#4595)

The headers from environment variables are expected to be URL encoded according to the spec. This change tries to URL decode them. See open-telemetry/opentelemetry-specification#3832 See https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/protocol/exporter.md#specifying-headers-via-environment-variables
micrometer-metrics · Jan 31, 2024 · 33bb267 · 33bb267
1 parent 58aa718
commit 33bb267
Show file tree

Hide file tree

Showing 2 changed files with 23 additions and 2 deletions.
diff --git a/...ations/micrometer-registry-otlp/src/main/java/io/micrometer/registry/otlp/OtlpConfig.java b/...ations/micrometer-registry-otlp/src/main/java/io/micrometer/registry/otlp/OtlpConfig.java
@@ -18,6 +18,7 @@
 import io.micrometer.core.instrument.config.validate.Validated;
 import io.micrometer.core.instrument.push.PushRegistryConfig;
 
+import java.net.URLDecoder;
 import java.util.Arrays;
 import java.util.Map;
 import java.util.Objects;
@@ -131,6 +132,14 @@ default Map<String, String> headers() {
             headersString = env.getOrDefault("OTEL_EXPORTER_OTLP_HEADERS", "").trim();
             String metricsHeaders = env.getOrDefault("OTEL_EXPORTER_OTLP_METRICS_HEADERS", "").trim();
             headersString = Objects.equals(headersString, "") ? metricsHeaders : headersString + "," + metricsHeaders;
+            try {
+                // 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 (Exception e) {
+                throw new IllegalArgumentException("Cannot decode header value: " + headersString, e);
+            }
         }
 
         String[] keyValues = Objects.equals(headersString, "") ? new String[] {} : headersString.split(",");

diff --git a/...ns/micrometer-registry-otlp/src/test/java/io/micrometer/registry/otlp/OtlpConfigTest.java b/...ns/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;
 
@@ -62,8 +63,19 @@ void headersConfigTakesPrecedenceOverEnvVars() throws Exception {
     @Test
     void headersUseEnvVarWhenConfigNotSet() throws Exception {
         OtlpConfig config = k -> null;
-        withEnvironmentVariable("OTEL_EXPORTER_OTLP_HEADERS", "header2=value")
-            .execute(() -> assertThat(config.headers()).containsEntry("header2", "value").hasSize(1));
+        withEnvironmentVariable("OTEL_EXPORTER_OTLP_HEADERS", "header2=va%20lue,header3=f oo")
+            .execute(() -> assertThat(config.headers()).containsEntry("header2", "va lue")
+                .containsEntry("header3", "f oo")
+                .hasSize(2));
+    }
+
+    @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