Merge pull request #7 from skpr/custom-headers

Adds config file and ability to add custom headers

Dockerfile

@@ -1,4 +1,4 @@
-FROM golang:latest AS builder
+FROM golang:1.19 AS builder
 
 LABEL stage=builder
 RUN mkdir -p /go/src/github.com/skpr/proxy-app
@@ -11,7 +11,11 @@ RUN GO111MODULE=on GOOS=linux GOARCH=amd64 CGO_ENABLED=0 go build -a -ldflags '-
 FROM skpr/base:1.x
 
 ENV PROXY_APP_ADDR=":8080"
-ENV PROXY_APP_MAX_AGE="5m"
+ENV PROXY_APP_CONFIG_FILE_PATH="/etc/skpr/proxy-app/config.yaml"
+
+ADD example/config.yaml /etc/skpr/proxy-app/config.yaml
+
+RUN cat $PROXY_APP_CONFIG_FILE_PATH
 
 COPY --from=builder /go/src/github.com/skpr/proxy-app/proxy-app /usr/local/bin/proxy-app
 RUN chmod +x /usr/local/bin/proxy-app

example/config.yaml

@@ -0,0 +1,3 @@
+responseHeaders:
+  Cache-Control: "max-age=300, public"
+  # Strict-Transport-Security: "max-age=86400; includeSubDomains"

go.mod

@@ -6,5 +6,6 @@ require (
 	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/skpr/go-config v0.0.0-20210803015120-ef4cd8061d76
 	github.com/stretchr/testify v1.7.0 // indirect
+	gopkg.in/yaml.v2 v2.2.2
 	gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b // indirect
 )

go.sum

@@ -10,6 +10,7 @@ github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81P
 github.com/stretchr/testify v1.7.0 h1:nwc3DEeHmmLAfoZucVR881uASk0Mfjw8xYJ99tb5CcY=
 github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v2 v2.2.2 h1:ZCJp+EgiOT7lHqUV2J862kp8Qj64Jo6az82+3Td9dZw=
 gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
 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=

internal/config/config.go

@@ -0,0 +1,31 @@
+package config
+
+import (
+	"fmt"
+	"os"
+
+	"gopkg.in/yaml.v2"
+)
+
+// File for configuring the proxy application behaviours.
+type File struct {
+	// ResponseHeaders to be added to all responses.
+	ResponseHeaders map[string]string `yaml:"responseHeaders"`
+}
+
+// Load config file from path.
+func Load(path string) (File, error) {
+	var file File
+
+	data, err := os.ReadFile(path)
+	if err != nil {
+		return file, fmt.Errorf("failed to load file: %w", err)
+	}
+
+	err = yaml.Unmarshal(data, &file)
+	if err != nil {
+		return file, fmt.Errorf("failed to marshal data: %w", err)
+	}
+
+	return file, nil
+}

internal/server/server.go

@@ -3,11 +3,11 @@ package server
 import (
 	"encoding/base64"
 	"fmt"
+	"github.com/skpr/proxy-app/internal/config"
 	"net/http"
 	"net/http/httputil"
 	"net/url"
 	"strings"
-	"time"
 )
 
 // RunParams is passed to the Run() function.
@@ -22,8 +22,6 @@ type RunParams struct {
 	Password string
 	// TrimPathPrefix from backend requests.
 	TrimPathPrefix string
-	// MaxAge applied to a response.
-	MaxAge string
 }
 
 // Validate the server parameters.
@@ -36,24 +34,15 @@ func (p RunParams) Validate() error {
 		return fmt.Errorf("not provided: endpoint")
 	}
 
-	if p.MaxAge == "" {
-		return fmt.Errorf("not provided: max-age")
-	}
-
 	return nil
 }
 
 // Run the server.
-func Run(params RunParams) error {
+func Run(params RunParams, config config.File) error {
 	if err := params.Validate(); err != nil {
 		return fmt.Errorf("validation failed: %w", err)
 	}
 
-	maxAge, err := time.ParseDuration(params.MaxAge)
-	if err != nil {
-		return fmt.Errorf("failed to parse max age: %w", err)
-	}
-
 	endpoint, err := url.Parse(params.Endpoint)
 	if err != nil {
 		return fmt.Errorf("failed to parse endpoint: %w", err)
@@ -82,7 +71,10 @@ func Run(params RunParams) error {
 	}
 
 	proxy.ModifyResponse = func(r *http.Response) error {
-		r.Header.Set("Cache-Control", fmt.Sprintf("max-age=%v, public", maxAge.Seconds()))
+		for headerKey, headerValue := range config.ResponseHeaders {
+			r.Header.Set(headerKey, headerValue)
+		}
+
 		return nil
 	}
 

main.go

@@ -2,9 +2,11 @@ package main
 
 import (
 	"errors"
+	"fmt"
 	"os"
 
 	skprconfig "github.com/skpr/go-config"
+	"github.com/skpr/proxy-app/internal/config"
 	"github.com/skpr/proxy-app/internal/server"
 )
 
@@ -19,8 +21,6 @@ const (
 	EnvSkprConfigKeyPassword = "PROXY_APP_CONFIG_KEY_PASSWORD"
 	// EnvSkprConfigKeyTrimPathPrefix used to load the path prefix value from Skpr config.
 	EnvSkprConfigKeyTrimPathPrefix = "PROXY_APP_CONFIG_KEY_TRIM_PATH_PREFIX"
-	// EnvSkprConfigKeyMaxAge used to set the max-age for all responses.
-	EnvSkprConfigKeyMaxAge = "PROXY_APP_CONFIG_KEY_MAX_AGE"
 
 	// EnvAddr sets the address for the proxy application.
 	EnvAddr = "PROXY_APP_ADDR"
@@ -32,8 +32,8 @@ const (
 	EnvPassword = "PROXY_APP_PASSWORD"
 	// EnvTrimPathPrefix strips the path prefix from backend requests.
 	EnvTrimPathPrefix = "PROXY_APP_TRIM_PATH_PREFIX"
-	// EnvMaxAge used to set the max-age for all responses.
-	EnvMaxAge = "PROXY_APP_MAX_AGE"
+	// EnvConfigFilePath is used to load a file which configures this app's advanced behaviours.
+	EnvConfigFilePath = "PROXY_APP_CONFIG_FILE_PATH"
 )
 
 func main() {
@@ -48,10 +48,16 @@ func main() {
 		Username:       skprclient.GetWithFallback(os.Getenv(EnvSkprConfigKeyUsername), os.Getenv(EnvUsername)),
 		Password:       skprclient.GetWithFallback(os.Getenv(EnvSkprConfigKeyPassword), os.Getenv(EnvPassword)),
 		TrimPathPrefix: skprclient.GetWithFallback(os.Getenv(EnvSkprConfigKeyTrimPathPrefix), os.Getenv(EnvTrimPathPrefix)),
-		MaxAge:         skprclient.GetWithFallback(os.Getenv(EnvSkprConfigKeyMaxAge), os.Getenv(EnvMaxAge)),
 	}
 
-	if err := server.Run(params); err != nil {
+	configFile, err := config.Load(os.Getenv(EnvConfigFilePath))
+	if err != nil {
+		panic(err)
+	}
+
+	fmt.Println(configFile)
+
+	if err := server.Run(params, configFile); err != nil {
 		panic(err)
 	}
 }