New configuration for commands/handlers to run after updates

* The new configuration includes specific commands per file, as well
    as handlers that can be triggered by updates but will only ever run
    once.
  * For now, commands from the pre_commands section are executed, the
    rest is ignored

buildcert.go

@@ -206,12 +206,12 @@ func (b *tCertificateBuilder) RunCommandsIfChanged() error {
 		log.Debug("Not running commands")
 		return nil
 	}
-	for i := range b.config.AfterUpdate {
+	for i := range b.config.AfterUpdate.PreCommands {
 		err := b.RunCommand(i)
 		if err != nil {
 			return fmt.Errorf(
 				"Failed while executing command '%s': %w",
-				b.config.AfterUpdate[i],
+				b.config.AfterUpdate.PreCommands[i],
 				err,
 			)
 		}
@@ -224,9 +224,9 @@ func (b *tCertificateBuilder) RunCommand(pos int) error {
 	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
 	defer cancel()
 
-	log := b.logger.WithField("command", b.config.AfterUpdate[pos])
+	log := b.logger.WithField("command", b.config.AfterUpdate.PreCommands[pos])
 	log.Debug("Executing command")
-	cmd := exec.CommandContext(ctx, "sh", "-c", b.config.AfterUpdate[pos])
+	cmd := exec.CommandContext(ctx, "sh", "-c", b.config.AfterUpdate.PreCommands[pos])
 	output, err := cmd.CombinedOutput()
 	if len(output) != 0 {
 		if utf8.Valid(output) {

config.go

@@ -59,6 +59,16 @@ type (
 		Servers   []tLdapServerConfig   `yaml:"servers"`
 	}
 
+	// Handlers. Each handler has a name and contains a list of commands.
+	tHandlers map[string][]string
+
+	// Certificate file updates configuration.
+	tCertFileUpdateConfig struct {
+		PreCommands  []string  `yaml:"pre_commands"`
+		Handlers     tHandlers `yaml:"handlers"`
+		PostCommands []string  `yaml:"post_commands"`
+	}
+
 	// Certificate file configuration.
 	tCertificateFileConfig struct {
 		Path           string                `yaml:"path"`
@@ -71,7 +81,7 @@ type (
 		CAChainOf      string                `yaml:"ca_chain_of"`
 		Reverse        bool                  `yaml:"reverse"`
 		AppendFiles    []string              `yaml:"append_files"`
-		AfterUpdate    []string    `yaml:"after_update"`
+		AfterUpdate    tCertFileUpdateConfig `yaml:"after_update"`
 	}
 
 	// Main configuration.

fetch-certificates.yml.example

@@ -53,6 +53,15 @@ ldap:
     - host: ldap1.example.org
     - host: ldap2.example.org
 
+# Handlers. Certificate updates can specify that a handler must be executed
+# if the PEM file is replaced. A handler will only be executed once for all
+# triggered updates. Each handler is a list of commands. When a handler runs,
+# the first command that fails will stop the execution.
+handlers:
+  apache:
+    - /usr/sbin/apache2ctl configtest
+    - /usr/sbin/apache2ctl graceful
+
 # Certificates that must be updated
 certificates:
 
@@ -89,7 +98,15 @@ certificates:
     # A list of files to append to the output.
     append_files:
       - /some/other/file.pem
-    # A list of commands that will be executed when the file is replaced.
+    # Define what must be done after an update.
-    # If one of the commands fails, execution will stop.
     after_update:
-      - apache2ctl graceful
+      # Commands to execute before handlers are run. The order of the commands
+      # is respected. If a command fails to run, execution stops.
+      pre_commands: []
+      # Handlers to trigger. Handlers will still be executed if a pre-command
+      # had failed but they were triggered by more than one update. Execution
+      # order is arbitrary.
+      handlers:
+        - apache
+      # Commands to execute after handlers are run.
+      post_commands: []