fix: support PARCA_BEARER_TOKEN environment variable for BearerToken config

This mirrors the Parca Agent's flags: https://github.com/parca-dev/parca-agent/blob/v0.41.1/flags/flags.go#L325

Author: metalmatze

README.md

@@ -155,7 +155,8 @@ Flags:
       --profile-share-server="api.pprof.me:443"
                                  gRPC address to send share profile requests to.
       --store-address=STRING     gRPC address to send profiles and symbols to.
-      --bearer-token=STRING      Bearer token to authenticate with store.
+      --bearer-token=STRING      Bearer token to authenticate with store
+                                 ($PARCA_BEARER_TOKEN).
       --bearer-token-file=STRING
                                  File to read bearer token from to authenticate
                                  with store.

pkg/parca/parca.go

@@ -120,7 +120,7 @@ type Flags struct {
 	ProfileShareServer string `default:"api.pprof.me:443" help:"gRPC address to send share profile requests to."`
 
 	StoreAddress       string            `kong:"help='gRPC address to send profiles and symbols to.'"`
-	BearerToken        string            `kong:"help='Bearer token to authenticate with store.'"`
+	BearerToken        string            `kong:"help='Bearer token to authenticate with store.',env='PARCA_BEARER_TOKEN'"`
 	BearerTokenFile    string            `kong:"help='File to read bearer token from to authenticate with store.'"`
 	Insecure           bool              `kong:"help='Send gRPC requests via plaintext instead of TLS.'"`
 	InsecureSkipVerify bool              `kong:"help='Skip TLS certificate verification.'"`