Add local Pyroscope server and Go continuous profiling

Add a docker-compose service running the Grafana Pyroscope backend on
port 4040 with a persistent data volume, and instrument the Go app via
github.com/grafana/pyroscope-go. The app pushes CPU, memory, and
goroutine profiles every 10s when pyroscope.enabled is set in
config.yaml. Config is extended with application_name and server_address
(defaults to http://localhost:4040). Document usage in the README.

1 files changed, 17 insertions, 0 deletions

diff --git a/config/config.go b/config/config.go
index 6fe9048..f95d3f8 100644
--- a/config/config.go
+++ b/config/config.go
@@ -16,6 +16,7 @@ type Config struct {
 	Storage       StorageConfig       `yaml:"storage"`
 	Strava        StravaConfig        `yaml:"strava"`
 	OfficialClimb OfficialClimbConfig `yaml:"official_climb"`
+	Pyroscope     PyroscopeConfig     `yaml:"pyroscope"`
 }
 
 type DatabaseConfig struct {
@@ -43,6 +44,12 @@ type OfficialClimbConfig struct {
 	MatchRadiusM float64 `yaml:"match_radius_m"`
 }
 
+type PyroscopeConfig struct {
+	Enabled         bool   `yaml:"enabled"`
+	ApplicationName string `yaml:"application_name"`
+	ServerAddress   string `yaml:"server_address"`
+}
+
 func Default() Config {
 	return Config{
 		Database: DatabaseConfig{Path: "biking_home.db"},
@@ -52,6 +59,10 @@ func Default() Config {
 		},
 		Storage:       StorageConfig{GPXDir: "data/rides"},
 		OfficialClimb: OfficialClimbConfig{MatchRadiusM: official_climb.DefaultMatchRadiusM},
+		Pyroscope: PyroscopeConfig{
+			ApplicationName: "biking_home",
+			ServerAddress:   "http://localhost:4040",
+		},
 	}
 }
 
@@ -73,6 +84,12 @@ func Load(filename string) (Config, error) {
 	if config.Storage.GPXDir == "" {
 		return Config{}, fmt.Errorf("config %q: storage.gpx_dir is required", filename)
 	}
+	if config.Pyroscope.Enabled && config.Pyroscope.ApplicationName == "" {
+		return Config{}, fmt.Errorf("config %q: pyroscope.application_name is required when pyroscope is enabled", filename)
+	}
+	if config.Pyroscope.Enabled && config.Pyroscope.ServerAddress == "" {
+		return Config{}, fmt.Errorf("config %q: pyroscope.server_address is required when pyroscope is enabled", filename)
+	}
 	if math.IsNaN(config.OfficialClimb.MatchRadiusM) || math.IsInf(config.OfficialClimb.MatchRadiusM, 0) || config.OfficialClimb.MatchRadiusM <= 0 {
 		return Config{}, fmt.Errorf("config %q: official_climb.match_radius_m must be greater than zero", filename)
 	}