Add option to set CLI flags via env variables

Author: martialblog

README.md

@@ -14,22 +14,24 @@ Available Commands:
   pipeline    Checks the status of the Logstash Pipelines
 
 Flags:
-  -H, --hostname string    Hostname of the Logstash server (default "localhost")
+  -H, --hostname string    Hostname of the Logstash server (CHECK_LOGSTASH_HOSTNAME) (default "localhost")
   -p, --port int           Port of the Logstash server (default 9600)
   -s, --secure             Use a HTTPS connection
   -i, --insecure           Skip the verification of the server's TLS certificate
-  -b, --bearer string      Specify the Bearer Token for server authentication
-  -u, --user string        Specify the user name and password for server authentication <user:password>
-      --ca-file string     Specify the CA File for TLS authentication
-      --cert-file string   Specify the Certificate File for TLS authentication
-      --key-file string    Specify the Key File for TLS authentication
+  -b, --bearer string      Specify the Bearer Token for server authentication (CHECK_LOGSTASH_BEARER)
+  -u, --user string        Specify the user name and password for server authentication <user:password> (CHECK_LOGSTASH_BASICAUTH)
+      --ca-file string     Specify the CA File for TLS authentication (CHECK_LOGSTASH_CA_FILE)
+      --cert-file string   Specify the Certificate File for TLS authentication (CHECK_LOGSTASH_CERT_FILE)
+      --key-file string    Specify the Key File for TLS authentication (CHECK_LOGSTASH_KEY_FILE)
   -t, --timeout int        Timeout in seconds for the CheckPlugin (default 30)
   -h, --help               help for check_logstash
   -v, --version            version for check_logstash
 ```
 
 The check plugin respects the environment variables `HTTP_PROXY`, `HTTPS_PROXY` and `NO_PROXY`.
 
+Various flags can be set with environment variables, refer to the help to see which flags.
+
 ### Health
 
 Checks the health status of the Logstash server.

cmd/config.go

@@ -15,12 +15,12 @@ import (
 )
 
 type Config struct {
-	BasicAuth string
-	Bearer    string
-	CAFile    string
-	CertFile  string
-	KeyFile   string
-	Hostname  string
+	BasicAuth string `env:"CHECK_LOGSTASH_BASICAUTH"`
+	Bearer    string `env:"CHECK_LOGSTASH_BEARER"`
+	CAFile    string `env:"CHECK_LOGSTASH_CA_FILE"`
+	CertFile  string `env:"CHECK_LOGSTASH_CERT_FILE"`
+	KeyFile   string `env:"CHECK_LOGSTASH_KEY_FILE"`
+	Hostname  string `env:"CHECK_LOGSTASH_HOSTNAME"`
 	Port      int
 	Info      bool
 	Insecure  bool

cmd/root.go

@@ -40,23 +40,23 @@ func init() {
 
 	pfs := rootCmd.PersistentFlags()
 	pfs.StringVarP(&cliConfig.Hostname, "hostname", "H", "localhost",
-		"Hostname of the Logstash server")
+		"Hostname of the Logstash server (CHECK_LOGSTASH_HOSTNAME)")
 	pfs.IntVarP(&cliConfig.Port, "port", "p", 9600,
 		"Port of the Logstash server")
 	pfs.BoolVarP(&cliConfig.Secure, "secure", "s", false,
 		"Use a HTTPS connection")
 	pfs.BoolVarP(&cliConfig.Insecure, "insecure", "i", false,
 		"Skip the verification of the server's TLS certificate")
 	pfs.StringVarP(&cliConfig.Bearer, "bearer", "b", "",
-		"Specify the Bearer Token for server authentication")
+		"Specify the Bearer Token for server authentication (CHECK_LOGSTASH_BEARER)")
 	pfs.StringVarP(&cliConfig.BasicAuth, "user", "u", "",
-		"Specify the user name and password for server authentication <user:password>")
+		"Specify the user name and password for server authentication <user:password> (CHECK_LOGSTASH_BASICAUTH)")
 	pfs.StringVarP(&cliConfig.CAFile, "ca-file", "", "",
-		"Specify the CA File for TLS authentication")
+		"Specify the CA File for TLS authentication (CHECK_LOGSTASH_CA_FILE)")
 	pfs.StringVarP(&cliConfig.CertFile, "cert-file", "", "",
-		"Specify the Certificate File for TLS authentication")
+		"Specify the Certificate File for TLS authentication (CHECK_LOGSTASH_CERT_FILE)")
 	pfs.StringVarP(&cliConfig.KeyFile, "key-file", "", "",
-		"Specify the Key File for TLS authentication")
+		"Specify the Key File for TLS authentication (CHECK_LOGSTASH_KEY_FILE)")
 	pfs.IntVarP(&Timeout, "timeout", "t", Timeout,
 		"Timeout in seconds for the CheckPlugin")
 
@@ -65,6 +65,8 @@ func init() {
 
 	help := rootCmd.HelpTemplate()
 	rootCmd.SetHelpTemplate(help + Copyright)
+
+	check.LoadFromEnv(&cliConfig)
 }
 
 func Usage(cmd *cobra.Command, _ []string) {