feat: Add support for custom certificates

lib/kamal/cli/app.rb

@@ -12,6 +12,7 @@ def boot
 
           KAMAL.roles_on(host).each do |role|
             Kamal::Cli::App::Assets.new(host, role, self).run
+            Kamal::Cli::App::SslCertificates.new(host, role, self).run
           end
         end
 

lib/kamal/cli/app/ssl_certificates.rb

@@ -0,0 +1,28 @@
+class Kamal::Cli::App::SslCertificates
+  attr_reader :host, :role, :sshkit
+  delegate :execute, :info, to: :sshkit
+
+  def initialize(host, role, sshkit)
+    @host = host
+    @role = role
+    @sshkit = sshkit
+  end
+
+  def run
+    if role.running_proxy? && role.proxy.custom_ssl_certificate?
+      info "Writing SSL certificates for #{role.name} on #{host}"
+      execute *app.create_ssl_directory
+      if cert_content = role.proxy.certificate_pem_content
+        execute *app.write_certificate_file(cert_content)
+      end
+      if key_content = role.proxy.private_key_pem_content
+        execute *app.write_private_key_file(key_content)
+      end
+    end
+  end
+
+  private
+    def app
+      @app ||= KAMAL.app(role: role, host: host)
+    end
+end

lib/kamal/commands/app/proxy.rb

@@ -21,6 +21,18 @@ def remove_proxy_app_directory
     remove_directory config.proxy_boot.app_directory
   end
 
+  def create_ssl_directory
+    make_directory(config.proxy_boot.tls_directory)
+  end
+
+  def write_certificate_file(content)
+    [ :sh, "-c", Kamal::Utils.sensitive("cat > #{config.proxy_boot.tls_directory}/cert.pem << 'KAMAL_CERT_EOF'\n#{content}\nKAMAL_CERT_EOF", redaction: "cat > #{config.proxy_boot.tls_directory}/cert.pem << 'KAMAL_CERT_EOF'\n[CERTIFICATE CONTENT REDACTED]\nKAMAL_CERT_EOF") ]
+  end
+
+  def write_private_key_file(content)
+    [ :sh, "-c", Kamal::Utils.sensitive("cat > #{config.proxy_boot.tls_directory}/key.pem << 'KAMAL_KEY_EOF'\n#{content}\nKAMAL_KEY_EOF", redaction: "cat > #{config.proxy_boot.tls_directory}/key.pem << 'KAMAL_KEY_EOF'\n[PRIVATE KEY CONTENT REDACTED]\nKAMAL_KEY_EOF") ]
+  end
+
   private
     def proxy_exec(*command)
       docker :exec, proxy_container_name, "kamal-proxy", *command

lib/kamal/configuration.rb

@@ -63,7 +63,7 @@ def initialize(raw_config, destination: nil, version: nil, validate: true)
     @env = Env.new(config: @raw_config.env || {}, secrets: secrets)
 
     @logging = Logging.new(logging_config: @raw_config.logging)
-    @proxy = Proxy.new(config: self, proxy_config: @raw_config.proxy)
+    @proxy = Proxy.new(config: self, proxy_config: @raw_config.proxy, secrets: secrets)
     @proxy_boot = Proxy::Boot.new(config: self)
     @ssh = Ssh.new(config: self)
     @sshkit = Sshkit.new(config: self)

lib/kamal/configuration/accessory.rb

@@ -125,7 +125,8 @@ def initialize_proxy
       Kamal::Configuration::Proxy.new \
         config: config,
         proxy_config: accessory_config["proxy"],
-        context: "accessories/#{name}/proxy"
+        context: "accessories/#{name}/proxy",
+        secrets: config.secrets
     end
 
     def initialize_registry

lib/kamal/configuration/docs/proxy.yml

@@ -11,7 +11,6 @@
 # run on the same proxy.
 #
 proxy:
-
   # Hosts
   #
   # The hosts that will be used to serve the app. The proxy will only route requests
@@ -45,7 +44,21 @@ proxy:
   # unless you explicitly set `forward_headers: true`
   #
   # Defaults to `false`:
-  ssl: true
+  ssl: ...
+
+  # Custom SSL certificate
+  #
+  # In some cases, using Let's Encrypt for automatic certificate management is not an 
+  # option, or you may already have SSL certificates issued by a different 
+  # Certificate Authority (CA). Kamal supports loading custom SSL certificates 
+  # directly from secrets.
+  #
+  # Examples:
+  #   ssl: true              # Enable SSL with Let's Encrypt
+  #   ssl: false             # Disable SSL
+  #   ssl:                   # Enable custom SSL
+  #     certificate_pem: CERTIFICATE_PEM
+  #     private_key_pem: PRIVATE_KEY_PEM
 
   # SSL redirect
   #

lib/kamal/configuration/proxy.rb

@@ -6,12 +6,13 @@ class Kamal::Configuration::Proxy
 
   delegate :argumentize, :optionize, to: Kamal::Utils
 
-  attr_reader :config, :proxy_config
+  attr_reader :config, :proxy_config, :secrets
 
-  def initialize(config:, proxy_config:, context: "proxy")
+  def initialize(config:, proxy_config:, secrets:, context: "proxy")
     @config = config
     @proxy_config = proxy_config
     @proxy_config = {} if @proxy_config.nil?
+    @secrets = secrets
     validate! @proxy_config, with: Kamal::Configuration::Validator::Proxy, context: context
   end
 
@@ -27,10 +28,42 @@ def hosts
     proxy_config["hosts"] || proxy_config["host"]&.split(",") || []
   end
 
+  def custom_ssl_certificate?
+    ssl = proxy_config["ssl"]
+    return false unless ssl.is_a?(Hash)
+    ssl["certificate_pem"].present? && ssl["private_key_pem"].present?
+  end
+
+  def certificate_pem_content
+    ssl = proxy_config["ssl"]
+    return nil unless ssl.is_a?(Hash)
+    secrets[ssl["certificate_pem"]]
+  end
+
+  def private_key_pem_content
+    ssl = proxy_config["ssl"]
+    return nil unless ssl.is_a?(Hash)
+    secrets[ssl["private_key_pem"]]
+  end
+
+  def certificate_pem
+    tls_file_path("cert.pem")
+  end
+
+  def private_key_pem
+    tls_file_path("key.pem")
+  end
+
+  def tls_file_path(filename)
+    File.join(config.proxy_boot.tls_container_directory, filename) if custom_ssl_certificate?
+  end
+
   def deploy_options
     {
       host: hosts,
-      tls: proxy_config["ssl"].presence,
+      tls: ssl? ? true : nil,
+      "tls-certificate-path": certificate_pem,
+      "tls-private-key-path": private_key_pem,
       "deploy-timeout": seconds_duration(config.deploy_timeout),
       "drain-timeout": seconds_duration(config.drain_timeout),
       "health-check-interval": seconds_duration(proxy_config.dig("healthcheck", "interval")),
@@ -66,7 +99,7 @@ def stop_command_args(**options)
   end
 
   def merge(other)
-    self.class.new config: config, proxy_config: proxy_config.deep_merge(other.proxy_config)
+    self.class.new config: config, proxy_config: proxy_config.deep_merge(other.proxy_config), secrets: secrets
   end
 
   private

lib/kamal/configuration/proxy/boot.rb

@@ -100,6 +100,14 @@ def error_pages_container_directory
     File.join app_container_directory, "error_pages"
   end
 
+  def tls_directory
+    File.join app_directory, "tls"
+  end
+
+  def tls_container_directory
+    File.join app_container_directory, "tls"
+  end
+
   private
     def ensure_valid_bind_ips(bind_ips)
       bind_ips.present? && bind_ips.each do |ip|

lib/kamal/configuration/role.rb

@@ -150,8 +150,8 @@ def asset_volume_directory(version = config.version)
   end
 
   def ensure_one_host_for_ssl
-    if running_proxy? && proxy.ssl? && hosts.size > 1
-      raise Kamal::ConfigurationError, "SSL is only supported on a single server, found #{hosts.size} servers for role #{name}"
+    if running_proxy? && proxy.ssl? && hosts.size > 1 && !proxy.custom_ssl_certificate?
+      raise Kamal::ConfigurationError, "SSL is only supported on a single server unless you provide custom certificates, found #{hosts.size} servers for role #{name}"
     end
   end
 
@@ -173,6 +173,7 @@ def initialize_specialized_proxy
         @specialized_proxy = Kamal::Configuration::Proxy.new \
           config: config,
           proxy_config: proxy_config,
+          secrets: config.secrets,
           context: "servers/#{name}/proxy"
       end
     end

lib/kamal/configuration/validator.rb

@@ -24,7 +24,9 @@ def validate_against_example!(validation_config, example)
             example_value = example[key]
 
             if example_value == "..."
-              unless key.to_s == "proxy" && boolean?(value.class)
+              if key.to_s == "ssl"
+                validate_type! value, TrueClass, FalseClass, Hash
+              elsif key.to_s != "proxy" || !boolean?(value.class)
                 validate_type! value, *(Array if key == :servers), Hash
               end
             elsif key == "hosts"

lib/kamal/configuration/validator/proxy.rb

@@ -10,6 +10,16 @@ def validate!
       if (config.keys & [ "host", "hosts" ]).size > 1
         error "Specify one of 'host' or 'hosts', not both"
       end
+
+      if config["ssl"].is_a?(Hash)
+        if config["ssl"]["certificate_pem"].present? && config["ssl"]["private_key_pem"].blank?
+          error "Missing private_key_pem setting (required when certificate_pem is present)"
+        end
+
+        if config["ssl"]["private_key_pem"].present? && config["ssl"]["certificate_pem"].blank?
+          error "Missing certificate_pem setting (required when private_key_pem is present)"
+        end
+      end
     end
   end
 end

test/cli/app_test.rb

@@ -220,6 +220,21 @@ class CliAppTest < CliTestCase
     end
   end
 
+  test "boot with custom ssl certificate" do
+    Kamal::Configuration::Proxy.any_instance.stubs(:custom_ssl_certificate?).returns(true)
+    Kamal::Configuration::Proxy.any_instance.stubs(:certificate_pem_content).returns("CERTIFICATE CONTENT")
+    Kamal::Configuration::Proxy.any_instance.stubs(:private_key_pem_content).returns("PRIVATE KEY CONTENT")
+
+    stub_running
+    run_command("boot", config: :with_proxy).tap do |output|
+      assert_match "Writing SSL certificates for web on 1.1.1.1", output
+      assert_match "mkdir -p .kamal/proxy/apps-config/app/tls", output
+      assert_match "sh -c [REDACTED]", output
+      assert_match "--tls-certificate-path=\"/home/kamal-proxy/.apps-config/app/tls/cert.pem\"", output
+      assert_match "--tls-private-key-path=\"/home/kamal-proxy/.apps-config/app/tls/key.pem\"", output
+    end
+  end
+
   test "start" do
     SSHKit::Backend::Abstract.any_instance.stubs(:capture_with_info).returns("999") # old version
 

test/commands/app_test.rb

@@ -149,8 +149,6 @@ class CommandsAppTest < ActiveSupport::TestCase
       new_command.remove.join(" ")
   end
 
-
-
   test "logs" do
     assert_equal \
       "sh -c 'docker ps --latest --quiet --filter label=service=app --filter label=destination= --filter label=role=web --filter status=running --filter status=restarting --filter ancestor=$(docker image ls --filter reference=dhh/app:latest --format '\\''{{.ID}}'\\'') ; docker ps --latest --quiet --filter label=service=app --filter label=destination= --filter label=role=web --filter status=running --filter status=restarting' | head -1 | xargs docker logs --timestamps 2>&1",

test/configuration/proxy/boot_test.rb

@@ -25,5 +25,7 @@ class ConfigurationProxyBootTest < ActiveSupport::TestCase
     assert_equal "/home/kamal-proxy/.apps-config/app", @proxy_boot_config.app_container_directory
     assert_equal ".kamal/proxy/apps-config/app/error_pages", @proxy_boot_config.error_pages_directory
     assert_equal "/home/kamal-proxy/.apps-config/app/error_pages", @proxy_boot_config.error_pages_container_directory
+    assert_equal ".kamal/proxy/apps-config/app/tls", @proxy_boot_config.tls_directory
+    assert_equal "/home/kamal-proxy/.apps-config/app/tls", @proxy_boot_config.tls_container_directory
   end
 end

test/configuration/proxy_test.rb

@@ -45,6 +45,64 @@ class ConfigurationProxyTest < ActiveSupport::TestCase
     end
   end
 
+  test "ssl with certificate and private key from secrets" do
+    with_test_secrets("secrets" => "CERT_PEM=certificate\nKEY_PEM=private_key") do
+      @deploy[:proxy] = {
+        "ssl" => {
+          "certificate_pem" => "CERT_PEM",
+          "private_key_pem" => "KEY_PEM"
+        },
+        "host" => "example.com"
+      }
+
+      proxy = config.proxy
+      assert_equal "/home/kamal-proxy/.apps-config/app/tls/cert.pem", proxy.certificate_pem
+      assert_equal "/home/kamal-proxy/.apps-config/app/tls/key.pem", proxy.private_key_pem
+    end
+  end
+
+  test "deploy options with custom ssl certificates" do
+    with_test_secrets("secrets" => "CERT_PEM=certificate\nKEY_PEM=private_key") do
+      @deploy[:proxy] = {
+        "ssl" => {
+          "certificate_pem" => "CERT_PEM",
+          "private_key_pem" => "KEY_PEM"
+        },
+        "host" => "example.com"
+      }
+
+      proxy = config.proxy
+      options = proxy.deploy_options
+      assert_equal true, options[:tls]
+      assert_equal "/home/kamal-proxy/.apps-config/app/tls/cert.pem", options[:"tls-certificate-path"]
+      assert_equal "/home/kamal-proxy/.apps-config/app/tls/key.pem", options[:"tls-private-key-path"]
+    end
+  end
+
+  test "ssl with certificate and no private key" do
+    with_test_secrets("secrets" => "CERT_PEM=certificate") do
+      @deploy[:proxy] = {
+        "ssl" => {
+          "certificate_pem" => "CERT_PEM"
+        },
+        "host" => "example.com"
+      }
+      assert_raises(Kamal::ConfigurationError) { config.proxy.ssl? }
+    end
+  end
+
+  test "ssl with private key and no certificate" do
+    with_test_secrets("secrets" => "KEY_PEM=private_key") do
+      @deploy[:proxy] = {
+        "ssl" => {
+          "private_key_pem" => "KEY_PEM"
+        },
+        "host" => "example.com"
+      }
+      assert_raises(Kamal::ConfigurationError) { config.proxy.ssl? }
+    end
+  end
+
   private
     def config
       Kamal::Configuration.new(@deploy)

test/configuration_test.rb

@@ -386,7 +386,7 @@ class ConfigurationTest < ActiveSupport::TestCase
       Kamal::Configuration.new(@deploy_with_roles)
     end
 
-    assert_equal "SSL is only supported on a single server, found 2 servers for role workers", exception.message
+    assert_equal "SSL is only supported on a single server unless you provide custom certificates, found 2 servers for role workers", exception.message
   end
 
   test "two proxy ssl roles with same host" do