Add experimental healthcheck support

README.md

@@ -16,15 +16,17 @@ The following environment variables can be used to configure the service.
 | Name | Default | Description
 | -| -| -
 | `TESTDUMMY_BIND_ADDRESS` | `:8000` | The address to bind the service to
+| `TESTDUMMY_ENABLE_ENV` | `false` | Enable the `/env` endpoint which dumps env vars. :warning: This can be a security risk so enable with caution
+| `TESTDUMMY_ENABLE_REQUEST_LOGGING` | `false` | Logs all requests to stdout
 | `TESTDUMMY_HEALTHY` | `true` | Boolean. When `true` `/health` returns an HTTP 200 response. When `false` `/health`  returns an empty HTTP 500 response.
 | `TESTDUMMY_HEALTHY_AFTER_SECONDS` | | When set, sets the health status to `false` (regardless of `TESTDUMMY_HEALTHY`) until the specified number of seconds. This is useful for testing post deployment "warmup" scenarios.
+| `TESTDUMMY_HEALTHCHECK_PG_DSN` | | When set, adds a healthcheck for the specified Postgres DSN (e.g. postgres://test:test@0.0.0.0:5432/test?sslmode=disable)
 | `TESTDUMMY_PANIC_SECONDS` | | When set, specifies the number of seconds to wait before panicking. This is useful for testing crash recovery scenarios.
-| `TESTDUMMY_ENABLE_REQUEST_LOGGING` | `false` | Logs all requests to stdout
-| `TESTDUMMY_ENABLE_ENV` | `false` | Enable the `/env` endpoint which dumps env vars. :warning: This can be a security risk so enable with caution
 | `TESTDUMMY_ROOT_PATH` | `/` | The root path for all routes
 | `TESTDUMMY_STRESS_CPU_DURATION` | `0s` | Ping endpoints will perform a naive CPU stress test on all cores for the supplied duration
 
 
+
 ## API
 
 | Path | Description
@@ -34,6 +36,7 @@ The following environment variables can be used to configure the service.
 | `/env` | Returns all environment variables in the format `NAME=VALUE`, one per line.
 | `/exit?code={exitCode}` | Causes the process to exit with a default exit code of `1`. Use the `code` parameter to customize the exit code.
 | <code>/health?healthy={true&#124;false}</code> | Returns an empty HTTP 200 if healthy, otherwise an empty HTTP 500.  The healthy status can be changed using the optional `healthy` query parameter. This status persists for the lifetime of the process. See the [Environment Variables](#environment-variables) section for related options.
+| `/healthcheck` | Runs specific healthchecks as configured via the `TESTDUMMY_HEALTHCHECK_*` environment variables.
 | `/status?status={statusCode}` | Returns the supplied HTTP status code
 | `/version` | Returns the testdummy version
 

go.mod

@@ -8,8 +8,15 @@ require (
 	github.com/stretchr/testify v1.9.0
 )
 
+require (
+	github.com/lib/pq v1.10.9 // indirect
+	go.opentelemetry.io/otel v1.24.0 // indirect
+	go.opentelemetry.io/otel/trace v1.24.0 // indirect
+)
+
 require (
 	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/hellofresh/health-go/v5 v5.5.3
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 )

go.sum

@@ -1,13 +1,25 @@
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/google/go-cmp v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI=
+github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
+github.com/hellofresh/health-go/v5 v5.5.3 h1:i+mfJcA8te/QhBzrBZxOw344XgIvHrc9IQzrEyn3OUQ=
+github.com/hellofresh/health-go/v5 v5.5.3/go.mod h1:maWprKoK7N9zno7l2ubFEGVF2SDmTHq5D9sV+lCFmGs=
 github.com/kelseyhightower/envconfig v1.4.0 h1:Im6hONhd3pLkfDFsbRgu68RDNkGF1r3dvMUtDTo2cv8=
 github.com/kelseyhightower/envconfig v1.4.0/go.mod h1:cccZRl6mQpaq41TPp5QxidR+Sa3axMbJDNb//FQX6Gg=
+github.com/lib/pq v1.10.9 h1:YXG7RB+JIjhP29X+OtkiDnYaXQwpS4JEWq7dtCCRUEw=
+github.com/lib/pq v1.10.9/go.mod h1:AlVN5x4E4T544tWzH6hKfbfQvm3HdbOxrmggDNAPY9o=
 github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
 github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/objx v0.5.2 h1:xuMeJ0Sdp5ZMRXx/aWO6RZxdr3beISkG5/G/aIRr3pY=
+github.com/stretchr/objx v0.5.2/go.mod h1:FRsXN1f5AsAjCGJKqEizvkpNtU+EGNCLh3NxZ/8L+MA=
 github.com/stretchr/testify v1.9.0 h1:HtqpIVDClZ4nwg75+f6Lvsy/wHu+3BoSGCbBAcpTsTg=
 github.com/stretchr/testify v1.9.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
+go.opentelemetry.io/otel v1.24.0 h1:0LAOdjNmQeSTzGBzduGe/rU4tZhMwL5rWgtp9Ku5Jfo=
+go.opentelemetry.io/otel v1.24.0/go.mod h1:W7b9Ozg4nkF5tWI5zsXkaKKDjdVjpD4oAt9Qi/MArHo=
+go.opentelemetry.io/otel/trace v1.24.0 h1:CsKnnL4dUAr/0llH9FKuc698G04IrpWV0MQA/Y1YELI=
+go.opentelemetry.io/otel/trace v1.24.0/go.mod h1:HPc3Xr/cOApsBI154IU0OI0HJexz+aw5uPdbs3UCjNU=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=

main.go

@@ -14,6 +14,9 @@ import (
 
 	"github.com/kelseyhightower/envconfig"
 	"github.com/pkg/errors"
+
+	"github.com/hellofresh/health-go/v5"
+	healthPg "github.com/hellofresh/health-go/v5/checks/postgres"
 )
 
 // versionString is overwritten using compiler ldflags
@@ -32,6 +35,7 @@ type RuntimeConfig struct {
 	EnableEnv            bool   `split_words:"true" default:"false"`
 	RootPath             string `split_words:"true" default:"/"`
 	StressCpuDuration    string `split_words:"true" default:"0s"`
+	HealthcheckPgDsn     string `split_words:"true"`
 }
 
 func main() {
@@ -62,7 +66,7 @@ func main() {
 		Handler: logging(rc, logger)(mux),
 	}
 
-	addRoute := func(path string, handler func(http.ResponseWriter, *http.Request)) {
+	addRoute := func(path string, handler http.HandlerFunc) {
 		mux.HandleFunc(filepath.Join(rc.RootPath, path), handler)
 	}
 
@@ -73,9 +77,11 @@ func main() {
 	addRoute("ping", func(w http.ResponseWriter, r *http.Request) { pingHandler(w, r, stressDuration) })
 	addRoute("echo", echoHandler)
 	addRoute("health", healthHandler)
+	addRoute("healthcheck", createHealthcheckHandlerFunc(rc))
 	addRoute("version", versionHandler)
 	addRoute("exit", exitHandler)
 	addRoute("status", statusHandler)
+
 	if rc.EnableEnv {
 		logger.Println("WARNING: /env is enabled. This may expose sensitive information.")
 		addRoute("env", envHandler)
@@ -216,3 +222,22 @@ func logging(rc RuntimeConfig, logger *log.Logger) func(http.Handler) http.Handl
 		})
 	}
 }
+
+func createHealthcheckHandlerFunc(rc RuntimeConfig) http.HandlerFunc {
+	healthChecker, err := health.New()
+	LogIfErr(err, "Error creating health checker")
+
+	if rc.HealthcheckPgDsn != "" {
+		err = healthChecker.Register(health.Config{
+			Name:      "postgres",
+			Timeout:   time.Second * 2,
+			SkipOnErr: false,
+			Check: healthPg.New(healthPg.Config{
+				DSN: rc.HealthcheckPgDsn,
+			}),
+		})
+		LogIfErr(err, "Error registering Postgres health check")
+	}
+
+	return healthChecker.HandlerFunc
+}