first (BIG) commit

config/config.go

@@ -0,0 +1,78 @@
+// Package config implements a solution for parsing a configuration file ("gotenberg.yml")
+// and populating an instance of Config which will be used accross the application.
+package config
+
+import (
+	"fmt"
+	"io/ioutil"
+	"text/template"
+
+	"gopkg.in/yaml.v2"
+)
+
+// Config represents the data provided by a YAML file.
+type Config struct {
+	// Port the port the application will listen to.
+	Port string `yaml:"port"`
+	// LogLevel the log level used by the logger of the application.
+	LogLevel string `yaml:"logLevel"`
+	// Commands the commands' templates from the configuration file.
+	Commands struct {
+		// HTMLtoPDF the command's template to convert an HTML file to a PDF file.
+		HTMLtoPDF string `yaml:"HTMLtoPDF"`
+		// WordToPDF the command's template to convert a Word file to a PDF file.
+		WordToPDF string `yaml:"WordToPDF"`
+		// MergePDF the command's template to merge many PDF files into one final PDF file.
+		MergePDF string `yaml:"MergePDF"`
+	} `yaml:"commands"`
+	// Templates gathers all instances of Template which will be created from previous
+	// Commands block.
+	Templates struct {
+		// HTMLtoPDF the instance of template created from Commands.HTMLtoPDF.
+		HTMLtoPDF *template.Template
+		// WordToPDF the instance of template created from Commands.HTMLtoPDF.
+		WordToPDF *template.Template
+		// MergePDF the instance of template created from Commands.HTMLtoPDF.
+		MergePDF *template.Template
+	}
+}
+
+// AppConfig is the configuration instance used accross the application.
+var AppConfig *Config
+
+// configurationFilePath is our default configuration file to parse.
+const configurationFilePath = "gotenberg.yml"
+
+// MakeConfig instantiates our configuration by parsing a YAML file.
+func MakeConfig() error {
+	AppConfig = &Config{}
+
+	data, err := ioutil.ReadFile(configurationFilePath)
+	if err != nil {
+		return err
+	}
+
+	if err := yaml.Unmarshal(data, &AppConfig); err != nil {
+		return err
+	}
+
+	tmpl, err := template.New("HTMLToPDF").Parse(AppConfig.Commands.HTMLtoPDF)
+	if err != nil {
+		return fmt.Errorf("Unable to parse the HTML to PDF command: %s", err)
+	}
+	AppConfig.Templates.HTMLtoPDF = tmpl
+
+	tmpl, err = template.New("WordToPDF").Parse(AppConfig.Commands.WordToPDF)
+	if err != nil {
+		return fmt.Errorf("Unable to parse the Word to PDF command: %s", err)
+	}
+	AppConfig.Templates.WordToPDF = tmpl
+
+	tmpl, err = template.New("MergePDF").Parse(AppConfig.Commands.MergePDF)
+	if err != nil {
+		return fmt.Errorf("Unable to parse the merge PDF command: %s", err)
+	}
+	AppConfig.Templates.MergePDF = tmpl
+
+	return nil
+}