new config struct

config.go

+package main
+
+import (
+	log "github.com/sirupsen/logrus"
+	"os"
+)
+
+type Configuration struct {
+	DomainsListPath string
+}
+
+var configuration Configuration
+func readConfig() {
+	configuration.DomainsListPath = requireEnvVar("DOMAINS_LIST_PATH")
+}
+
+func requireEnvVar(envName string) string {
+	full_env_key := "MCA_" + envName
+	val, ok := os.LookupEnv(full_env_key)
+	if !ok {
+		log.Fatal("Required environment variable is not set: ", full_env_key)
+	}
+	return val
+}

go.mod

@@ -3,10 +3,13 @@ module nogweii.net/go/my-certificate-alert
 go 1.16
 
 require (
-	github.com/CaliDog/certstream-go v0.0.0-20200713031452-eca7997412f1 // indirect
-	github.com/gobwas/glob v0.2.3 // indirect
+	github.com/CaliDog/certstream-go v0.0.0-20200713031452-eca7997412f1
+	github.com/gobwas/glob v0.2.3
 	github.com/gorilla/websocket v1.4.2 // indirect
 	github.com/jmoiron/jsonq v0.0.0-20150511023944-e874b168d07e // indirect
 	github.com/pkg/errors v0.9.1 // indirect
-	github.com/sirupsen/logrus v1.8.1 // indirect
+	github.com/sirupsen/logrus v1.8.1
+	github.com/stretchr/testify v1.7.0 // indirect
+	golang.org/x/sys v0.0.0-20210510120138-977fb7262007 // indirect
+	gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b // indirect
 )

go.sum

 github.com/CaliDog/certstream-go v0.0.0-20200713031452-eca7997412f1 h1:P2kAob5k67YLNGJg0C6Wg0nTLrUpIxYvpPFVrk1y1PQ=
 github.com/CaliDog/certstream-go v0.0.0-20200713031452-eca7997412f1/go.mod h1:JBo69gi8JyPpZoLZgmZeXiq4o7Ib2qf2RiIxiWC0oYQ=
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+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/gobwas/glob v0.2.3 h1:A4xDbljILXROh+kObIiy5kIaPYD8e96x1tgBhUI5J+Y=
 github.com/gobwas/glob v0.2.3/go.mod h1:d3Ez4x06l9bZtSvzIay5+Yzi0fmZzPgnTbPcKjJAkT8=
@@ -9,9 +11,18 @@ github.com/jmoiron/jsonq v0.0.0-20150511023944-e874b168d07e h1:ZZCvgaRDZg1gC9/1x
 github.com/jmoiron/jsonq v0.0.0-20150511023944-e874b168d07e/go.mod h1:+rHyWac2R9oAZwFe1wGY2HBzFJJy++RHBg1cU23NkD8=
 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/sirupsen/logrus v1.8.1 h1:dJKuHgqk1NNQlqoA6BTlM1Wf9DOH3NBjQyu0h9+AZZE=
 github.com/sirupsen/logrus v1.8.1/go.mod h1:yWOB1SBYBC5VeMP7gHvWumXLIWorT60ONWic61uBYv0=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
-golang.org/x/sys v0.0.0-20191026070338-33540a1f6037 h1:YyJpGZS1sBuBCzLAR1VEpK193GlqGZbnPFnPV/5Rsb4=
+github.com/stretchr/testify v1.7.0 h1:nwc3DEeHmmLAfoZucVR881uASk0Mfjw8xYJ99tb5CcY=
+github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 golang.org/x/sys v0.0.0-20191026070338-33540a1f6037/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20210510120138-977fb7262007 h1:gG67DSER+11cZvqIMb8S8bt0vZtiN6xWYARwirrOSfE=
+golang.org/x/sys v0.0.0-20210510120138-977fb7262007/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
+gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b h1:h8qDotaEPuJATrMmW04NCwg7v22aHH28wwpauUhK9Oo=
+gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

main.go

@@ -17,11 +17,8 @@ func main() {
 		"version": "0.0.0", // TODO: actually get the version number
 	}).Info("Starting my certificate alert")
 
-	domains_list_path := os.Getenv("MCA_DOMAINS_LIST")
-	if domains_list_path == "" {
-		log.Fatal("Must specify a path to a file with environment variable $MCA_DOMAINS_LIST")
-	}
-	readDomainsFromFile(domains_list_path)
+	readConfig()
+	readDomainsFromFile(configuration.DomainsListPath)
 
 	stream, errStream := certstream.CertStreamEventStream(true)