Initial version

.dockerignore

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+*.exe
+Dockerfile
+*.crt
+*.key

.github/dependabot.yml

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+# To get started with Dependabot version updates, you'll need to specify which
+# package ecosystems to update and where the package manifests are located.
+# Please see the documentation for all configuration options:
+# https://docs.github.com/github/administering-a-repository/configuration-options-for-dependency-updates
+
+version: 2
+updates:
+  - package-ecosystem: "gomod"
+    directory: "/"
+    schedule:
+      interval: "weekly"
+  - package-ecosystem: "docker"
+    directory: "/"
+    schedule:
+      interval: "weekly"

.github/workflows/docker-image.yml

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+name: Docker Image CI
+
+on:
+  push:
+    branches: [ "main" ]
+  pull_request:
+    branches: [ "main" ]
+
+jobs:
+
+  build:
+
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v3
+    - name: Build the Docker image
+      run: docker build . --file Dockerfile --tag my-image-name:$(date +%s)

.github/workflows/docker-publish.yml

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+name: Docker
+
+# This workflow uses actions that are not certified by GitHub.
+# They are provided by a third-party and are governed by
+# separate terms of service, privacy policy, and support
+# documentation.
+
+on:
+  schedule:
+    - cron: '27 23 * * *'
+  push:
+    branches: [ "main" ]
+    # Publish semver tags as releases.
+    tags: [ 'v*.*.*' ]
+  pull_request:
+    branches: [ "main" ]
+
+env:
+  # Use docker.io for Docker Hub if empty
+  REGISTRY: ghcr.io
+  # github.repository as <account>/<repo>
+  IMAGE_NAME: ${{ github.repository }}
+
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      packages: write
+      # This is used to complete the identity challenge
+      # with sigstore/fulcio when running outside of PRs.
+      id-token: write
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v3
+
+      # Install the cosign tool except on PR
+      # https://github.com/sigstore/cosign-installer
+      - name: Install cosign
+        if: github.event_name != 'pull_request'
+        uses: sigstore/cosign-installer@6e04d228eb30da1757ee4e1dd75a0ec73a653e06 #v3.1.1
+        with:
+          cosign-release: 'v2.1.1'
+
+      # Set up BuildKit Docker container builder to be able to build
+      # multi-platform images and export cache
+      # https://github.com/docker/setup-buildx-action
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@f95db51fddba0c2d1ec667646a06c2ce06100226 # v3.0.0
+
+      # Login against a Docker registry except on PR
+      # https://github.com/docker/login-action
+      - name: Log into registry ${{ env.REGISTRY }}
+        if: github.event_name != 'pull_request'
+        uses: docker/login-action@343f7c4344506bcbf9b4de18042ae17996df046d # v3.0.0
+        with:
+          registry: ${{ env.REGISTRY }}
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      # Extract metadata (tags, labels) for Docker
+      # https://github.com/docker/metadata-action
+      - name: Extract Docker metadata
+        id: meta
+        uses: docker/metadata-action@96383f45573cb7f253c731d3b3ab81c87ef81934 # v5.0.0
+        with:
+          images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
+
+      # Build and push Docker image with Buildx (don't push on PR)
+      # https://github.com/docker/build-push-action
+      - name: Build and push Docker image
+        id: build-and-push
+        uses: docker/build-push-action@0565240e2d4ab88bba5387d719585280857ece09 # v5.0.0
+        with:
+          context: .
+          push: ${{ github.event_name != 'pull_request' }}
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}
+          cache-from: type=gha
+          cache-to: type=gha,mode=max
+
+      # Sign the resulting Docker image digest except on PRs.
+      # This will only write to the public Rekor transparency log when the Docker
+      # repository is public to avoid leaking data.  If you would like to publish
+      # transparency data even for private images, pass --force to cosign below.
+      # https://github.com/sigstore/cosign
+      - name: Sign the published Docker image
+        if: ${{ github.event_name != 'pull_request' }}
+        env:
+          # https://docs.github.com/en/actions/security-guides/security-hardening-for-github-actions#using-an-intermediate-environment-variable
+          TAGS: ${{ steps.meta.outputs.tags }}
+          DIGEST: ${{ steps.build-and-push.outputs.digest }}
+        # This step uses the identity token to provision an ephemeral certificate
+        # against the sigstore community Fulcio instance.
+        run: echo "${TAGS}" | xargs -I {} cosign sign --yes {}@${DIGEST}

.gitignore

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+*.exe
+*.crt
+*.key

Dockerfile

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+FROM golang:1.21@sha256:9baee0edab4139ae9b108fffabb8e2e98a67f0b259fd25283c2a084bd74fea0d AS builder
+
+COPY . /build
+
+RUN cd /build && \
+    go build ./cmd/http-auth-server
+
+FROM gcr.io/distroless/base-debian12:nonroot@sha256:5a779e9c2635dbea68ae7988f398f95686ccde186cd2abf51207e41ed2ec51f4
+
+COPY --from=builder /build/http-auth-server /app/http-auth-server
+
+ENV AUTH_LISTEN=":9091"
+
+ENTRYPOINT [ "/app/http-auth-server" ]

cmd/http-auth-server/main.go

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+package main
+
+import (
+	"log/slog"
+	"net/http"
+	"net/url"
+	"os"
+	"time"
+
+	"github.com/andrewheberle/go-http-auth-server/pkg/sp"
+	"github.com/spf13/pflag"
+	"github.com/spf13/viper"
+)
+
+func main() {
+	// command line flags
+	pflag.String("cert", "", "HTTPS Certificate")
+	pflag.String("key", "", "HTTPS Key")
+	pflag.String("listen", "127.0.0.1:9091", "Listen address")
+	pflag.String("sp-cert", "", "Service Provider Certificate")
+	pflag.String("sp-key", "", "Service Provider Key")
+	pflag.String("sp-url", "http://localhost:9091", "Service Provider URL")
+	pflag.StringToString("sp-claim-mapping", map[string]string{"urn:oasis:names:tc:SAML:attribute:subject-id": "remote-user", "mail": "remote-email", "displayName": "remote-name", "role": "remote-groups"}, "Mapping of claims to headers")
+	pflag.String("metadata", "", "IdP Metadata URL")
+	pflag.Bool("debug", false, "Enable debug logging")
+	pflag.Parse()
+
+	// bind to viper
+	viper.BindPFlags(pflag.CommandLine)
+
+	// load from environment
+	viper.SetEnvPrefix("auth")
+	viper.AutomaticEnv()
+
+	// logging setup
+	var logLevel = new(slog.LevelVar)
+	logHandler := slog.NewTextHandler(os.Stderr, &slog.HandlerOptions{Level: logLevel})
+	slog.SetDefault(slog.New(logHandler))
+	if viper.GetBool("debug") {
+		logLevel.Set(slog.LevelDebug)
+	}
+
+	// validate service provider root url
+	root, err := url.Parse(viper.GetString("sp-url"))
+	if err != nil {
+		slog.Error("problem with SP URL", err)
+		os.Exit(1)
+	}
+
+	// validate metadata url
+	metadata, err := url.Parse(viper.GetString("metadata"))
+	if err != nil {
+		slog.Error("problem with IdP metadata URL", err)
+		os.Exit(1)
+	}
+
+	// set up auth provider
+	provider, err := sp.NewServiceProvider(viper.GetString("sp-cert"), viper.GetString("sp-key"), metadata, root, viper.GetStringMapString("sp-claim-mapping"))
+	if err != nil {
+		slog.Error("problem setting up SP", err)
+		os.Exit(1)
+	}
+
+	// set up auth endpoints
+	http.HandleFunc("/api/verify", provider.ForwardAuthHandler)
+	http.HandleFunc("/api/authz/forward-auth", provider.ForwardAuthHandler)
+
+	// set up saml endpoints
+	http.HandleFunc(provider.AcsURL().Path, provider.ACSHandler)
+	http.HandleFunc(provider.MetadataURL().Path, provider.MetadataHandler)
+	http.HandleFunc(provider.LogoutUrl().Path, provider.LogoutHandler)
+
+	// login endpoint
+	http.Handle("/login", provider.RequireAccount(http.HandlerFunc((func(w http.ResponseWriter, r *http.Request) {
+		w.Write([]byte("Logged In."))
+	}))))
+
+	// dummy endpoint
+
+	srv := &http.Server{
+		Addr:         viper.GetString("listen"),
+		ReadTimeout:  time.Second * 3,
+		WriteTimeout: time.Second * 3,
+	}
+
+	slog.Info("starting service",
+		"listen", srv.Addr,
+		"idp-metadata-url", metadata.String(),
+		"sp-acs-url", provider.AcsURL().String(),
+		"sp-metdata-url", provider.MetadataURL().String(),
+		"sp-logout-url", provider.LogoutUrl().String(),
+	)
+
+	if err := srv.ListenAndServe(); err != nil {
+		slog.Error("problem with SP URL", err)
+		os.Exit(1)
+	}
+}

go.mod

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+module github.com/andrewheberle/go-http-auth-server
+
+go 1.21.4
+
+require (
+	github.com/crewjam/saml v0.4.14
+	github.com/spf13/pflag v1.0.5
+	github.com/spf13/viper v1.17.0
+)
+
+require (
+	github.com/beevik/etree v1.1.0 // indirect
+	github.com/crewjam/httperr v0.2.0 // indirect
+	github.com/fsnotify/fsnotify v1.6.0 // indirect
+	github.com/golang-jwt/jwt/v4 v4.4.3 // indirect
+	github.com/hashicorp/hcl v1.0.0 // indirect
+	github.com/jonboulle/clockwork v0.2.2 // indirect
+	github.com/magiconair/properties v1.8.7 // indirect
+	github.com/mattermost/xml-roundtrip-validator v0.1.0 // indirect
+	github.com/mitchellh/mapstructure v1.5.0 // indirect
+	github.com/pelletier/go-toml/v2 v2.1.0 // indirect
+	github.com/pkg/errors v0.9.1 // indirect
+	github.com/russellhaering/goxmldsig v1.3.0 // indirect
+	github.com/sagikazarmark/locafero v0.3.0 // indirect
+	github.com/sagikazarmark/slog-shim v0.1.0 // indirect
+	github.com/sourcegraph/conc v0.3.0 // indirect
+	github.com/spf13/afero v1.10.0 // indirect
+	github.com/spf13/cast v1.5.1 // indirect
+	github.com/subosito/gotenv v1.6.0 // indirect
+	go.uber.org/atomic v1.9.0 // indirect
+	go.uber.org/multierr v1.9.0 // indirect
+	golang.org/x/crypto v0.14.0 // indirect
+	golang.org/x/exp v0.0.0-20230905200255-921286631fa9 // indirect
+	golang.org/x/sys v0.13.0 // indirect
+	golang.org/x/text v0.13.0 // indirect
+	gopkg.in/ini.v1 v1.67.0 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
+)