agent spec bypass proxy for cloud metadata (#785)

* try to bypass proxy for metadata * Apply suggestions from code review Co-authored-by: Trent Mick <[email protected]> * add more context why it makes sense --------- Co-authored-by: Trent Mick <[email protected]>
elastic · Apr 19, 2023 · ecf4ce6 · ecf4ce6
1 parent 6b807a5
commit ecf4ce6
Showing 1 changed file with 18 additions and 0 deletions.
diff --git a/specs/agents/metadata.md b/specs/agents/metadata.md
@@ -211,6 +211,12 @@ Fetching of cloud metadata for services running as AWS Lambda functions follow a
 
 [Metadata about an EC2 instance](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/instancedata-data-retrieval.html) can be retrieved from the internal metadata endpoint, `http://169.254.169.254`.
 
+In the case where a proxy is configured on the application, the agents SHOULD attempt to make
+the calls to the metadata endpoint directly, without using the proxy.
+This is recommended as those HTTP calls could be caller-sensitive and have to be made directly
+ by the virtual machine where the APM agent executes, also, the `169.254.x.x` IP address range
+is reserved for "link-local" addresses that are not routed.
+
 As an example with curl, first, an API token must be created
 
 ```sh
@@ -239,6 +245,12 @@ From the returned metadata, the following fields are useful
 Metadata about a GCP machine instance can be retrieved from the 
 metadata service, `http://metadata.google.internal`.
 
+In the case where a proxy is configured on the application, the agents SHOULD attempt to make
+the calls to the metadata endpoint directly, without using the proxy.
+This is recommended as those HTTP calls could be caller-sensitive and have to be made directly
+ by the virtual machine where the APM agent executes, also, the `169.254.x.x` IP address range
+is reserved for "link-local" addresses that are not routed.
+
 An example with curl
 
 ```sh
@@ -265,6 +277,12 @@ From the returned metadata, the following fields are useful
 Metadata about an Azure VM can be retrieved from the internal metadata
 endpoint, `http://169.254.169.254`.
 
+In the case where a proxy is configured on the application, the agents SHOULD attempt to make
+the calls to the metadata endpoint directly, without using the proxy.
+This is recommended as those HTTP calls could be caller-sensitive and have to be made directly
+ by the virtual machine where the APM agent executes, also, the `169.254.x.x` IP address range
+is reserved for "link-local" addresses that are not routed.
+
 An example with curl
 
 ```sh