Implementing comments from @danielnelson

plugins/inputs/all/all.go

@@ -96,7 +96,7 @@ import (
 	_ "github.com/influxdata/telegraf/plugins/inputs/socket_listener"
 	_ "github.com/influxdata/telegraf/plugins/inputs/solr"
 	_ "github.com/influxdata/telegraf/plugins/inputs/sqlserver"
-	_ "github.com/influxdata/telegraf/plugins/inputs/ssl_cert"
+	_ "github.com/influxdata/telegraf/plugins/inputs/x509_cert"
 	_ "github.com/influxdata/telegraf/plugins/inputs/statsd"
 	_ "github.com/influxdata/telegraf/plugins/inputs/syslog"
 	_ "github.com/influxdata/telegraf/plugins/inputs/sysstat"

plugins/inputs/x509_cert/README.md

@@ -0,0 +1,45 @@
+# X509 Cert Input Plugin
+
+This plugin provides information about X509 certificate accessible via local
+file or network connection.
+
+
+### Configuration
+
+```toml
+# Reads metrics from a SSL certificate
+[[inputs.x509_cert]]
+  ## List of local SSL files
+  # files = ["/etc/ssl/certs/ssl-cert-snakeoil.pem"]
+  ## List of servers
+  # servers = ["tcp://example.org:443"]
+  ## Timeout for SSL connection
+  # timeout = 5
+  ## Optional TLS Config
+  # tls_ca = "/etc/telegraf/ca.pem"
+  # tls_cert = "/etc/telegraf/cert.pem"
+  # tls_key = "/etc/telegraf/key.pem"
+  ## Use TLS but skip chain & host verification
+  # insecure_skip_verify = false
+```
+
+
+### Metrics
+
+- `x509_cert`
+  - tags:
+    - `server` (only if `servers` parameter is defined)
+    - `file` (only if `files` parameter is defined)
+  - fields:
+    - `expiry` (int, seconds)
+    - `age` (int, seconds)
+    - `startdate` (int, seconds)
+    - `enddate` (int, seconds)
+
+
+### Example output
+
+```
+x509_cert,server=google.com:443,host=myhost age=1753627i,expiry=5503972i,startdate=1516092060i,enddate=1523349660i 1517845687000000000
+x509_cert,host=myhost,file=/path/to/the.crt age=7522207i,expiry=308002732i,startdate=1510323480i,enddate=1825848420i 1517845687000000000
+```