feat(aws): add a fallback for expiration key (#4455)

* feat(aws): add a fallback for `expiration`

* fix(aws): intermittent test failures

- extend the time range from `-2s,0s` to `-5s,+2s`

* fix: `docs/config/README.md` readability

Co-authored-by: David Knaack <davidkna@users.noreply.github.com>

Co-authored-by: David Knaack <davidkna@users.noreply.github.com>

docs/config/README.md

@@ -328,6 +328,9 @@ When using [AWSume](https://awsu.me) the profile
 is read from the `AWSUME_PROFILE` env var and the credentials expiration
 date is read from the `AWSUME_EXPIRATION` env var.
 
+When using [saml2aws](https://github.com/Versent/saml2aws) the expiration information obtained from `~/.aws/credentials`
+falls back to the `x_security_token_expires` key.
+
 ### Options
 
 | Option              | Default                                                           | Description                                                                                                 |

src/modules/aws.rs

@@ -131,8 +131,10 @@ fn get_credentials_duration(
         let creds = get_creds(context, aws_creds)?;
         let section = get_profile_creds(creds, aws_profile)?;
 
-        section
-            .get("expiration")
+        let expiration_keys = ["expiration", "x_security_token_expires"];
+        expiration_keys
+            .iter()
+            .find_map(|expiration_key| section.get(expiration_key))
             .and_then(|expiration| DateTime::parse_from_rfc3339(expiration).ok())
     }?;
 
@@ -655,17 +657,20 @@ credential_process = /opt/bin/awscreds-retriever
 
         let expiration_date = now_plus_half_hour.to_rfc3339_opts(chrono::SecondsFormat::Secs, true);
 
+        let expiration_keys = ["expiration", "x_security_token_expires"];
+        expiration_keys.iter().for_each(|key| {
             file.write_all(
                 format!(
                     "[astronauts]
 aws_access_key_id=dummy
 aws_secret_access_key=dummy
-expiration={}
+{}={}
 ",
-                expiration_date
+                    key, expiration_date
                 )
                 .as_bytes(),
-        )?;
+            )
+            .unwrap();
 
             let actual = ModuleRenderer::new("aws")
                 .env("AWS_PROFILE", "astronauts")
@@ -691,8 +696,10 @@ expiration={}
             );
 
             // In principle, "30m" should be correct. However, bad luck in scheduling
-        // on shared runners may delay it. Allow for up to 2 seconds of delay.
-        let possible_values = ["30m", "29m59s", "29m58s"];
+            // on shared runners may delay it.
+            let possible_values = [
+                "30m2s", "30m1s", "30m", "29m59s", "29m58s", "29m57s", "29m56s", "29m55s",
+            ];
             let possible_values = possible_values.map(|duration| {
                 let segment_colored = format!("☁️  astronauts (ap-northeast-2) [{}] ", duration);
                 Some(format!(
@@ -701,7 +708,11 @@ expiration={}
                 ))
             });
 
-        assert!(possible_values.contains(&actual));
+            assert!(
+                possible_values.contains(&actual),
+                "time is not in range: {actual:?}"
+            );
+        });
 
         dir.close()
     }