feat(core): add stringToLogLevel utility

packages/opentelemetry-core/src/index.ts

@@ -88,6 +88,7 @@ export { merge } from './utils/merge';
 export { TimeoutError, callWithTimeout } from './utils/timeout';
 export { isUrlIgnored, urlMatches } from './utils/url';
 export { BindOnceFuture } from './utils/callback';
+export { stringToLogLevel } from './utils/configuration';
 import { _export } from './internal/exporter';
 export const internal = {
   _export,

packages/opentelemetry-core/src/utils/configuration.ts

@@ -0,0 +1,51 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+import { diag, DiagLogLevel } from '@opentelemetry/api';
+import { inspect } from 'util';
+
+const logLevelMap: { [key: string]: DiagLogLevel } = {
+  ALL: DiagLogLevel.ALL,
+  VERBOSE: DiagLogLevel.VERBOSE,
+  DEBUG: DiagLogLevel.DEBUG,
+  INFO: DiagLogLevel.INFO,
+  WARN: DiagLogLevel.WARN,
+  ERROR: DiagLogLevel.ERROR,
+  NONE: DiagLogLevel.NONE,
+};
+
+/**
+ * Convert a string to a {@link DiagLogLevel}, defaults to {@link DiagLogLevel} if the log level does not exist or undefined if the input is undefined.
+ * @param value
+ */
+export function stringToLogLevel(
+  value: string | undefined
+): DiagLogLevel | undefined {
+  if (value == null) {
+    // don't fall back to default - no value set has different semantics for ús than an incorrect value (do not set vs. fall back to default)
+    return undefined;
+  }
+
+  const resolvedLogLevel = logLevelMap[value.toUpperCase()];
+
+  if (resolvedLogLevel == null) {
+    diag.warn(
+      `Cannot resolve log level ${inspect(value)}, expected one of ${inspect(Object.keys(logLevelMap))}, using default`
+    );
+    return DiagLogLevel.INFO;
+  }
+
+  return resolvedLogLevel;
+}