diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 059f78a..f0816fa 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -1,5 +1,8 @@
 name: CI
 on:
+  pull_request:
+    branches:
+      - main
   push:
     paths:
       - 'run-specs-in-docker.sh'
diff --git a/amqproxy b/amqproxy
new file mode 160000
index 0000000..d09258d
--- /dev/null
+++ b/amqproxy
@@ -0,0 +1 @@
+Subproject commit d09258d8dec72b178e756e33ec806b70ee9fc94a
diff --git a/spec/Dockerfile b/spec/Dockerfile
index 6a46850..a17ff95 100644
--- a/spec/Dockerfile
+++ b/spec/Dockerfile
@@ -11,6 +11,9 @@ RUN shards install
 COPY src/ src/
 COPY spec/ spec/
 
+COPY spec/config.ini /tmp/config.ini
+COPY spec/config_empty.ini /tmp/config_empty.ini
+
 COPY spec/entrypoint.sh /entrypoint.sh
 RUN chmod +x /entrypoint.sh
 ENTRYPOINT ["/entrypoint.sh"]
diff --git a/spec/amqproxy/config_spec.cr b/spec/amqproxy/config_spec.cr
new file mode 100644
index 0000000..d9425cf
--- /dev/null
+++ b/spec/amqproxy/config_spec.cr
@@ -0,0 +1,189 @@
+require "spec"
+require "../../src/amqproxy/config"
+
+describe AMQProxy::Config do
+  it "loads defaults when no ini file, env vars or options are available" do
+    previous_argv = ARGV.clone
+    ARGV.clear
+
+    ARGV.concat([
+      "--config=/tmp/non_existing_file.ini",
+    ])
+
+    config = AMQProxy::Config.load_with_cli(ARGV)
+
+    config.listen_address.should eq "localhost"
+    config.listen_port.should eq 5673
+    config.http_port.should eq 15673
+    config.log_level.should eq ::Log::Severity::Info
+    config.idle_connection_timeout.should eq 5
+    config.term_timeout.should eq -1
+    config.term_client_close_timeout.should eq 0
+    config.upstream.should eq nil
+
+    # Restore ARGV
+    ARGV.clear
+    ARGV.concat(previous_argv)
+  end
+
+  it "reads from empty config file returning default configuration" do
+    previous_argv = ARGV.clone
+    ARGV.clear
+
+    ARGV.concat(["--config=/tmp/config_empty.ini"])
+
+    config = AMQProxy::Config.load_with_cli(ARGV)
+
+    config.listen_address.should eq "localhost"
+    config.listen_port.should eq 5673
+    config.http_port.should eq 15673
+    config.log_level.should eq ::Log::Severity::Info
+    config.idle_connection_timeout.should eq 5
+    config.term_timeout.should eq -1
+    config.term_client_close_timeout.should eq 0
+    config.upstream.should eq nil
+
+    # Restore ARGV
+    ARGV.clear
+    ARGV.concat(previous_argv)
+  end
+
+  it "reads from environment variables and overrules ini file values" do
+    previous_argv = ARGV.clone
+    ARGV.clear
+
+    ENV["LISTEN_ADDRESS"] = "example.com"
+    ENV["LISTEN_PORT"] = "5674"
+    ENV["HTTP_PORT"] = "15674"
+    ENV["LOG_LEVEL"] = "Error"
+    ENV["IDLE_CONNECTION_TIMEOUT"] = "12"
+    ENV["TERM_TIMEOUT"] = "13"
+    ENV["TERM_CLIENT_CLOSE_TIMEOUT"] = "14"
+    ENV["UPSTREAM"] = "amqp://localhost:5674"
+
+    config = AMQProxy::Config.load_with_cli(ARGV)
+
+    config.listen_address.should eq "example.com"
+    config.listen_port.should eq 5674
+    config.http_port.should eq 15674
+    config.log_level.should eq ::Log::Severity::Error
+    config.idle_connection_timeout.should eq 12
+    config.term_timeout.should eq 13
+    config.term_client_close_timeout.should eq 14
+    config.upstream.should eq "amqp://localhost:5674"
+
+    # Clean up
+    ENV.delete("LISTEN_ADDRESS")
+    ENV.delete("LISTEN_PORT")
+    ENV.delete("HTTP_PORT")
+    ENV.delete("LOG_LEVEL")
+    ENV.delete("IDLE_CONNECTION_TIMEOUT")
+    ENV.delete("TERM_TIMEOUT")
+    ENV.delete("TERM_CLIENT_CLOSE_TIMEOUT")
+    ENV.delete("UPSTREAM")
+
+    # Restore ARGV
+    ARGV.clear
+    ARGV.concat(previous_argv)
+  end
+
+  it "reads from command line arguments and overrules env vars" do
+    previous_argv = ARGV.clone
+    ARGV.clear
+
+    ENV["LISTEN_ADDRESS"] = "example.com"
+    ENV["LISTEN_PORT"] = "5674"
+    ENV["HTTP_PORT"] = "15674"
+    ENV["LOG_LEVEL"] = "Error"
+    ENV["IDLE_CONNECTION_TIMEOUT"] = "12"
+    ENV["TERM_TIMEOUT"] = "13"
+    ENV["TERM_CLIENT_CLOSE_TIMEOUT"] = "14"
+    ENV["UPSTREAM"] = "amqp://localhost:5674"
+
+    ARGV.concat([
+      "--listen=example_arg.com",
+      "--port=5675",
+      "--http-port=15675",
+      "--log-level=Warn",
+      "--idle-connection-timeout=15",
+      "--term-timeout=16",
+      "--term-client-close-timeout=17",
+      "amqp://localhost:5679",
+    ])
+
+    config = AMQProxy::Config.load_with_cli(ARGV)
+
+    config.listen_address.should eq "example_arg.com"
+    config.log_level.should eq ::Log::Severity::Warn
+    config.listen_port.should eq 5675
+    config.http_port.should eq 15675
+    config.idle_connection_timeout.should eq 15
+    config.term_timeout.should eq 16
+    config.term_client_close_timeout.should eq 17
+    config.upstream.should eq "amqp://localhost:5679"
+
+    # Clean Up
+    ENV.delete("LISTEN_ADDRESS")
+    ENV.delete("LISTEN_PORT")
+    ENV.delete("HTTP_PORT")
+    ENV.delete("LOG_LEVEL")
+    ENV.delete("IDLE_CONNECTION_TIMEOUT")
+    ENV.delete("TERM_TIMEOUT")
+    ENV.delete("TERM_CLIENT_CLOSE_TIMEOUT")
+    ENV.delete("UPSTREAM")
+
+    # Restore ARGV
+    ARGV.clear
+    ARGV.concat(previous_argv)
+  end
+
+  it "sets log level to debug when debug flag is present" do
+    previous_argv = ARGV.clone
+    ARGV.clear
+
+    ARGV.concat([
+      "--listen=example_arg.com",
+      "--port=5675",
+      "--http-port=15675",
+      "--log-level=Warn",
+      "--idle-connection-timeout=15",
+      "--term-timeout=16",
+      "--term-client-close-timeout=17",
+      "--debug",
+      "amqp://localhost:5679",
+    ])
+
+    config = AMQProxy::Config.load_with_cli(ARGV)
+
+    config.listen_address.should eq "example_arg.com"
+    config.log_level.should eq ::Log::Severity::Debug
+    config.listen_port.should eq 5675
+    config.http_port.should eq 15675
+    config.idle_connection_timeout.should eq 15
+    config.term_timeout.should eq 16
+    config.term_client_close_timeout.should eq 17
+    config.upstream.should eq "amqp://localhost:5679"
+
+    # Restore ARGV
+    ARGV.clear
+    ARGV.concat(previous_argv)
+  end
+
+  it "keeps the log level to trace when debug flag is present" do
+    previous_argv = ARGV.clone
+    ARGV.clear
+
+    ARGV.concat([
+      "--log-level=Trace",
+      "--debug",
+    ])
+
+    config = AMQProxy::Config.load_with_cli(ARGV)
+
+    config.log_level.should eq ::Log::Severity::Trace
+
+    # Restore ARGV
+    ARGV.clear
+    ARGV.concat(previous_argv)
+  end
+end
diff --git a/spec/config.ini b/spec/config.ini
new file mode 100644
index 0000000..ca38d1c
--- /dev/null
+++ b/spec/config.ini
@@ -0,0 +1,13 @@
+[main]
+log_level = debug
+idle_connection_timeout = 55
+term_timeout = 56
+term_client_close_timeout = 57
+upstream = amqp://localhost:5678
+
+[listen]
+bind = 127.0.0.1
+address = 127.0.0.2
+port = 5678
+http_port = 15678
+log_level = debug
diff --git a/spec/config_empty.ini b/spec/config_empty.ini
new file mode 100644
index 0000000..e69de29
diff --git a/src/amqproxy/cli.cr b/src/amqproxy/cli.cr
index 24e5ce2..511a0ef 100644
--- a/src/amqproxy/cli.cr
+++ b/src/amqproxy/cli.cr
@@ -1,3 +1,4 @@
+require "./config"
 require "./version"
 require "./server"
 require "./http_server"
@@ -9,94 +10,27 @@ require "log"
 class AMQProxy::CLI
   Log = ::Log.for(self)
 
-  @listen_address = "localhost"
-  @listen_port = 5673
-  @http_port = 15673
-  @log_level : ::Log::Severity = ::Log::Severity::Info
-  @idle_connection_timeout : Int32 = 5
-  @term_timeout = -1
-  @term_client_close_timeout = 0
+  @config : AMQProxy::Config? = nil
   @server : AMQProxy::Server? = nil
 
-  def parse_config(path) # ameba:disable Metrics/CyclomaticComplexity
-    INI.parse(File.read(path)).each do |name, section|
-      case name
-      when "main", ""
-        section.each do |key, value|
-          case key
-          when "upstream"                  then @upstream = value
-          when "log_level"                 then @log_level = ::Log::Severity.parse(value)
-          when "idle_connection_timeout"   then @idle_connection_timeout = value.to_i
-          when "term_timeout"              then @term_timeout = value.to_i
-          when "term_client_close_timeout" then @term_client_close_timeout = value.to_i
-          else                                  raise "Unsupported config #{name}/#{key}"
-          end
-        end
-      when "listen"
-        section.each do |key, value|
-          case key
-          when "port"            then @listen_port = value.to_i
-          when "bind", "address" then @listen_address = value
-          when "log_level"       then @log_level = ::Log::Severity.parse(value)
-          else                        raise "Unsupported config #{name}/#{key}"
-          end
-        end
-      else raise "Unsupported config section #{name}"
-      end
-    end
-  rescue ex
-    abort ex.message
-  end
-
-  def apply_env_variables
-    @listen_address = ENV["LISTEN_ADDRESS"]? || @listen_address
-    @listen_port = ENV["LISTEN_PORT"]?.try &.to_i || @listen_port
-    @http_port = ENV["HTTP_PORT"]?.try &.to_i || @http_port
-    @log_level = ENV["LOG_LEVEL"]?.try { |level| ::Log::Severity.parse(level) } || @log_level
-    @idle_connection_timeout = ENV["IDLE_CONNECTION_TIMEOUT"]?.try &.to_i || @idle_connection_timeout
-    @term_timeout = ENV["TERM_TIMEOUT"]?.try &.to_i || @term_timeout
-    @term_client_close_timeout = ENV["TERM_CLIENT_CLOSE_TIMEOUT"]?.try &.to_i || @term_client_close_timeout
-    @upstream = ENV["AMQP_URL"]? || @upstream
-  end
-
   def run(argv)
     raise "run cant be called multiple times" unless @server.nil?
 
-    # Parse config file first
-    OptionParser.parse(argv) do |parser|
-      parser.on("-c FILE", "--config=FILE", "Load config file") { |v| parse_config(v) }
-      parser.invalid_option { } # Invalid arguments are handled by the next OptionParser
-    end
-
-    apply_env_variables
+    # load cascading configuration. load sequence: defaults -> file -> env -> cli
+    config = @config = AMQProxy::Config.load_with_cli(argv)
 
-    # Parse CLI arguments
-    p = OptionParser.parse(argv) do |parser|
-      parser.banner = "Usage: amqproxy [options] [amqp upstream url]"
-      parser.on("-l ADDRESS", "--listen=ADDRESS", "Address to listen on (default is localhost)") do |v|
-        @listen_address = v
-      end
-      parser.on("-p PORT", "--port=PORT", "Port to listen on (default: 5673)") { |v| @listen_port = v.to_i }
-      parser.on("-b PORT", "--http-port=PORT", "HTTP Port to listen on (default: 15673)") { |v| @http_port = v.to_i }
-      parser.on("-t IDLE_CONNECTION_TIMEOUT", "--idle-connection-timeout=SECONDS", "Maximum time in seconds an unused pooled connection stays open (default 5s)") do |v|
-        @idle_connection_timeout = v.to_i
-      end
-      parser.on("--term-timeout=SECONDS", "At TERM the server waits SECONDS seconds for clients to gracefully close their sockets after Close has been sent (default: infinite)") do |v|
-        @term_timeout = v.to_i
-      end
-      parser.on("--term-client-close-timeout=SECONDS", "At TERM the server waits SECONDS seconds for clients to send Close before sending Close to clients (default: 0s)") do |v|
-        @term_client_close_timeout = v.to_i
-      end
-      parser.on("-d", "--debug", "Verbose logging") { @log_level = ::Log::Severity::Debug }
-      parser.on("-h", "--help", "Show this help") { puts parser.to_s; exit 0 }
-      parser.on("-v", "--version", "Display version") { puts AMQProxy::VERSION.to_s; exit 0 }
-      parser.invalid_option { |arg| abort "Invalid argument: #{arg}" }
-    end
+    log_backend = if ENV.has_key?("JOURNAL_STREAM")
+                    ::Log::IOBackend.new(formatter: Journal::LogFormat, dispatcher: ::Log::DirectDispatcher)
+                  else
+                    ::Log::IOBackend.new(formatter: Stdout::LogFormat, dispatcher: ::Log::DirectDispatcher)
+                  end
+    ::Log.setup_from_env(default_level: config.log_level, backend: log_backend)
 
-    @upstream ||= argv.shift?
-    upstream_url = @upstream || abort p.to_s
+    Log.debug { config.inspect }
 
+    upstream_url = config.upstream || abort "Upstream AMQP url is required. Add -h switch for help."
     u = URI.parse upstream_url
+
     abort "Invalid upstream URL" unless u.host
     default_port =
       case u.scheme
@@ -107,20 +41,13 @@ class AMQProxy::CLI
     port = u.port || default_port
     tls = u.scheme == "amqps"
 
-    log_backend = if ENV.has_key?("JOURNAL_STREAM")
-                    ::Log::IOBackend.new(formatter: Journal::LogFormat, dispatcher: ::Log::DirectDispatcher)
-                  else
-                    ::Log::IOBackend.new(formatter: Stdout::LogFormat, dispatcher: ::Log::DirectDispatcher)
-                  end
-    ::Log.setup_from_env(default_level: @log_level, backend: log_backend)
-
     Signal::INT.trap &->self.initiate_shutdown(Signal)
     Signal::TERM.trap &->self.initiate_shutdown(Signal)
 
-    server = @server = AMQProxy::Server.new(u.hostname || "", port, tls, @idle_connection_timeout)
+    server = @server = AMQProxy::Server.new(u.hostname || "", port, tls, config.idle_connection_timeout)
 
-    HTTPServer.new(server, @listen_address, @http_port.to_i)
-    server.listen(@listen_address, @listen_port.to_i)
+    HTTPServer.new(server, config.listen_address, config.http_port)
+    server.listen(config.listen_address, config.listen_port)
 
     shutdown
 
@@ -149,17 +76,22 @@ class AMQProxy::CLI
     unless server = @server
       raise "Can't call shutdown before run"
     end
+
+    unless config = @config
+      raise "Configuration has not been loaded"
+    end
+
     if server.client_connections > 0
-      if @term_client_close_timeout > 0
-        wait_for_clients_to_close @term_client_close_timeout.seconds
+      if config.term_client_close_timeout > 0
+        wait_for_clients_to_close config.term_client_close_timeout.seconds
       end
       server.disconnect_clients
     end
 
     if server.client_connections > 0
-      if @term_timeout >= 0
+      if config.term_timeout >= 0
         spawn do
-          sleep @term_timeout.seconds
+          sleep config.term_timeout.seconds
           abort "Exiting with #{server.client_connections} client connections still open"
         end
       end
diff --git a/src/amqproxy/config.cr b/src/amqproxy/config.cr
new file mode 100644
index 0000000..46626f7
--- /dev/null
+++ b/src/amqproxy/config.cr
@@ -0,0 +1,111 @@
+require "ini"
+require "log"
+require "option_parser"
+
+module AMQProxy
+  class Config
+    getter listen_address = "localhost"
+    getter listen_port = 5673
+    getter http_port = 15673
+    getter log_level = Log::Severity::Info
+    getter idle_connection_timeout = 5
+    getter term_timeout = -1
+    getter term_client_close_timeout = 0
+    getter upstream : String? = nil
+    getter debug : Bool? = nil
+    getter config_file = "config.ini"
+
+    protected def load_from_file # ameba:disable Metrics/CyclomaticComplexity
+      if config_file.empty? || !File.exists?(config_file)
+        return self
+      end
+
+      INI.parse(File.read(config_file)).each do |name, section|
+        case name
+        when "main", ""
+          section.each do |key, value|
+            case key
+            when "upstream"                  then @upstream = value
+            when "log_level"                 then @log_level = ::Log::Severity.parse(value)
+            when "idle_connection_timeout"   then @idle_connection_timeout = value.to_i
+            when "term_timeout"              then @term_timeout = value.to_i
+            when "term_client_close_timeout" then @term_client_close_timeout = value.to_i
+            else                                  raise "Unsupported config #{name}/#{key}"
+            end
+          end
+        when "listen"
+          section.each do |key, value|
+            case key
+            when "http_port"       then @http_port = value.to_i
+            when "port"            then @listen_port = value.to_i
+            when "bind", "address" then @listen_address = value
+            when "log_level"       then @log_level = ::Log::Severity.parse(value)
+            else                        raise "Unsupported config #{name}/#{key}"
+            end
+          end
+        else raise "Unsupported config section #{name}"
+        end
+      end
+
+      self
+    end
+
+    protected def load_from_env # ameba:disable Metrics/CyclomaticComplexity
+      @listen_address = ENV["LISTEN_ADDRESS"]? || @listen_address
+      @listen_port = ENV["LISTEN_PORT"]?.try &.to_i || @listen_port
+      @http_port = ENV["HTTP_PORT"]?.try &.to_i || @http_port
+      @log_level = Log::Severity.parse(ENV["LOG_LEVEL"]? || self.log_level.to_s) || @log_level
+      @idle_connection_timeout = ENV["IDLE_CONNECTION_TIMEOUT"]?.try &.to_i || @idle_connection_timeout
+      @term_timeout = ENV["TERM_TIMEOUT"]?.try &.to_i || @term_timeout
+      @term_client_close_timeout = ENV["TERM_CLIENT_CLOSE_TIMEOUT"]?.try &.to_i || @term_client_close_timeout
+      @upstream = ENV["AMQP_URL"]? || ENV["UPSTREAM"]? || @upstream
+
+      self
+    end
+
+    protected def load_cli_options(argv)
+      OptionParser.parse(argv) do |parser|
+        parser.on("-l ADDRESS", "--listen=ADDRESS", "Address to listen on (default is localhost)") do |v|
+          @listen_address = v
+        end
+        parser.on("-p PORT", "--port=PORT", "Port to listen on (default: 5673)") { |v| @listen_port = v.to_i }
+        parser.on("-b PORT", "--http-port=PORT", "HTTP Port to listen on (default: 15673)") { |v| @http_port = v.to_i }
+        parser.on("-t IDLE_CONNECTION_TIMEOUT", "--idle-connection-timeout=SECONDS", "Maximum time in seconds an unused pooled connection stays open (default 5s)") do |v|
+          @idle_connection_timeout = v.to_i
+        end
+        parser.on("--term-timeout=SECONDS", "At TERM the server waits SECONDS seconds for clients to gracefully close their sockets after Close has been sent (default: infinite)") do |v|
+          @term_timeout = v.to_i
+        end
+        parser.on("--term-client-close-timeout=SECONDS", "At TERM the server waits SECONDS seconds for clients to send Close beforing sending Close to clients (default: 0s)") do |v|
+          @term_client_close_timeout = v.to_i
+        end
+        parser.on("--log-level=LEVEL", "The log level (default: info)") { |v| @log_level = ::Log::Severity.parse(v) }
+        parser.on("-d", "--debug", "Verbose logging") { @debug = true }
+        parser.on("-c FILE", "--config=FILE", "Load config file") do |v|
+          @config_file = v
+        end
+        parser.on("-h", "--help", "Show this help") { puts parser.to_s; exit 0 }
+        parser.on("-v", "--version", "Display version") { puts AMQProxy::VERSION.to_s; exit 0 }
+        parser.invalid_option { |arg| abort "Invalid argument: #{arg}" }
+      end
+
+      @upstream = argv.shift? || @upstream
+
+      if @debug && @log_level > Log::Severity::Debug
+        @log_level = Log::Severity::Debug
+      end
+
+      self
+    end
+
+    def self.load_with_cli(argv)
+      new()
+        .load_cli_options(argv.dup) # handle config file/help/version options
+        .load_from_file
+        .load_from_env
+        .load_cli_options(argv)
+    rescue ex
+      abort ex.message
+    end
+  end
+end