[feature] Add a request ID and include it in logs (#1476)

This adds a lightweight form of tracing to GTS. Each incoming request is
assigned a Request ID which we then pass on and log in all our log
lines. Any function that gets called downstream from an HTTP handler
should now emit a requestID=value pair whenever it logs something.

Co-authored-by: kim <grufwub@gmail.com>

6 files changed, 42 insertions, 2 deletions

diff --git a/internal/config/config.go b/internal/config/config.go
index 516fb11d6..1dea90788 100644
--- a/internal/config/config.go
+++ b/internal/config/config.go
@@ -147,6 +147,8 @@ type Configuration struct {
 	AdminAccountPassword  string `name:"password" usage:"the password to set for this account"`
 	AdminTransPath        string `name:"path" usage:"the path of the file to import from/export to"`
 	AdminMediaPruneDryRun bool   `name:"dry-run" usage:"perform a dry run and only log number of items eligible for pruning"`
+
+	RequestIDHeader string `name:"request-id-header" usage:"Header to extract the Request ID from. Eg.,'X-Request-Id'"`
 }
 
 type CacheConfiguration struct {
diff --git a/internal/config/defaults.go b/internal/config/defaults.go
index 709f063ca..528419e97 100644
--- a/internal/config/defaults.go
+++ b/internal/config/defaults.go
@@ -163,4 +163,6 @@ var Defaults = Configuration{
 	},
 
 	AdminMediaPruneDryRun: true,
+
+	RequestIDHeader: "X-Request-Id",
 }
diff --git a/internal/config/flags.go b/internal/config/flags.go
index d8c31368b..3ef44bf62 100644
--- a/internal/config/flags.go
+++ b/internal/config/flags.go
@@ -140,6 +140,8 @@ func (s *ConfigState) AddServerFlags(cmd *cobra.Command) {
 		cmd.Flags().Int(AdvancedRateLimitRequestsFlag(), cfg.AdvancedRateLimitRequests, fieldtag("AdvancedRateLimitRequests", "usage"))
 		cmd.Flags().Int(AdvancedThrottlingMultiplierFlag(), cfg.AdvancedThrottlingMultiplier, fieldtag("AdvancedThrottlingMultiplier", "usage"))
 		cmd.Flags().Duration(AdvancedThrottlingRetryAfterFlag(), cfg.AdvancedThrottlingRetryAfter, fieldtag("AdvancedThrottlingRetryAfter", "usage"))
+
+		cmd.Flags().String(RequestIDHeaderFlag(), cfg.RequestIDHeader, fieldtag("RequestIDHeader", "usage"))
 	})
 }
 
diff --git a/internal/config/helpers.gen.go b/internal/config/helpers.gen.go
index 64e7d02f7..1a4c14a82 100644
--- a/internal/config/helpers.gen.go
+++ b/internal/config/helpers.gen.go
@@ -2977,3 +2977,28 @@ func GetAdminMediaPruneDryRun() bool { return global.GetAdminMediaPruneDryRun()
 
 // SetAdminMediaPruneDryRun safely sets the value for global configuration 'AdminMediaPruneDryRun' field
 func SetAdminMediaPruneDryRun(v bool) { global.SetAdminMediaPruneDryRun(v) }
+
+// GetRequestIDHeader safely fetches the Configuration value for state's 'RequestIDHeader' field
+func (st *ConfigState) GetRequestIDHeader() (v string) {
+	st.mutex.Lock()
+	v = st.config.RequestIDHeader
+	st.mutex.Unlock()
+	return
+}
+
+// SetRequestIDHeader safely sets the Configuration value for state's 'RequestIDHeader' field
+func (st *ConfigState) SetRequestIDHeader(v string) {
+	st.mutex.Lock()
+	defer st.mutex.Unlock()
+	st.config.RequestIDHeader = v
+	st.reloadToViper()
+}
+
+// RequestIDHeaderFlag returns the flag name for the 'RequestIDHeader' field
+func RequestIDHeaderFlag() string { return "request-id-header" }
+
+// GetRequestIDHeader safely fetches the value for global configuration 'RequestIDHeader' field
+func GetRequestIDHeader() string { return global.GetRequestIDHeader() }
+
+// SetRequestIDHeader safely sets the value for global configuration 'RequestIDHeader' field
+func SetRequestIDHeader(v string) { global.SetRequestIDHeader(v) }
diff --git a/internal/config/testdata/test.yaml b/internal/config/testdata/test.yaml
index 87fe105d2..c2d902944 100644
--- a/internal/config/testdata/test.yaml
+++ b/internal/config/testdata/test.yaml
@@ -415,4 +415,13 @@ cache:
   gts:
     account-max-size: 99
     account-ttl: "3h"
-    account-sweep-freq: "1s"
\ No newline at end of file
+    account-sweep-freq: "1s"
+
+##################################
+##### OBSERVABILITY SETTINGS #####
+##################################
+
+# String. Header name to use to extract a request or trace ID from. Typically set by a
+# loadbalancer or proxy.
+# Default: "X-Request-Id"
+request-id-header: "X-Trace-Id"
diff --git a/internal/config/validate.go b/internal/config/validate.go
index 765739d6c..866ec1be1 100644
--- a/internal/config/validate.go
+++ b/internal/config/validate.go
@@ -55,7 +55,7 @@ func Validate() error {
 		// no problem
 		break
 	case "http":
-		log.Warnf("%s was set to 'http'; this should *only* be used for debugging and tests!", ProtocolFlag())
+		log.Warnf(nil, "%s was set to 'http'; this should *only* be used for debugging and tests!", ProtocolFlag())
 	case "":
 		errs = append(errs, fmt.Errorf("%s must be set", ProtocolFlag()))
 	default: