Merge pull request #67 from minrk/traefik

Add HTTPS support with traefik

MANIFEST.in

@@ -1 +1,2 @@
 include tljh/systemd-units/*
+include tljh/*.tpl

docs/howto/https.rst

@@ -0,0 +1,79 @@
+.. _howto/https:
+
+============
+Enable HTTPS
+============
+
+Every JupyterHub deployment should enable HTTPS!
+HTTPS encrypts traffic so that usernames and passwords and other potentially sensitive bits of information are communicated securely.
+The Littlest JupyterHub supports automatically configuring HTTPS via `Let's Encrypt <https://letsencrypt.org>`_,
+or setting it up :ref:`manually <manual_https>` with your own TLS key and certificate.
+If you don't know how to do that,
+then :ref:`Let's Encrypt <letsencrypt>` is probably the right path for you.
+
+
+.. _letsencrypt:
+
+Automatic HTTPS with Let's Encrypt
+==================================
+
+To enable HTTPS via letsencrypt::
+
+    sudo -E tljh-config set https.enabled true
+    sudo -E tljh-config set https.letsencrypt.email you@example.com
+    sudo -E tljh-config add-item https.letsencrypt.domains yourhub.yourdomain.edu
+
+where ``you@example.com`` is your email address and ``yourhub.yourdomain.edu`` is the domain where your hub will be running.
+
+Once you have loaded this, your config should look like::
+
+    sudo -E tljh-config show
+
+
+.. sourcecode:: yaml
+
+    https:
+      enabled: true
+      letsencrypt:
+        email: you@example.com
+        domains:
+        - yourhub.yourdomain.edu
+
+Finally, you can reload the proxy to load the new configuration::
+
+    sudo -E tljh-config reload proxy
+
+At this point, the proxy should negotiate with Let's Encrypt to set up a trusted HTTPS certificate for you.
+It may take a moment for the proxy to negotiate with Let's Encrypt to get your certificates, after which you can access your Hub securely at https://yourhub.yourdomain.edu.
+
+.. _manual_https:
+
+Manual HTTPS with existing key and certificate
+==============================================
+
+You may already have an SSL key and certificate.
+If so, you can tell your deployment to use these files::
+
+    sudo -E tljh-config set https.enabled true
+    sudo -E tljh-config set https.tls.key /etc/mycerts/mydomain.key
+    sudo -E tljh-config set https.tls.cert /etc/mycerts/mydomain.cert
+
+
+Once you have loaded this, your config should look like::
+
+    sudo -E tljh-config show
+
+
+.. sourcecode:: yaml
+
+    https:
+      enabled: true
+      tls:
+        key: /etc/mycerts/mydomain.key
+        cert: /etc/mycerts/mydomain.cert
+
+Finally, you can reload the proxy to load the new configuration::
+
+    sudo -E tljh-config reload proxy
+
+and now access your Hub securely at https://yourhub.yourdomain.edu.

docs/index.rst

@@ -35,6 +35,9 @@ Ubuntu 18.04. We have a bunch of tutorials to get you started.
   You should use this if your cloud provider does not already have a direct tutorial,
   or if you have experience setting up servers.
 
+Once you are ready to run your server for real,
+it's a good idea to proceed directly to :doc:`howto/https`.
+
 Tutorials
 =========
 
@@ -53,6 +56,7 @@ How-To guides answer the question 'How do I...?' for a lot of topics.
 .. toctree::
    :titlesonly:
 
+   howto/https
    howto/user-environment
    howto/admin-users
    howto/notebook-interfaces

setup.py

@@ -12,11 +12,12 @@ setup(
     include_package_data=True,
     install_requires=[
         'pyyaml==3.*',
-        'ruamel.yaml==0.15.*'
+        'ruamel.yaml==0.15.*',
+        'jinja2',
     ],
     entry_points={
         'console_scripts': [
-            'tljh-config = tljh.config:main'
-        ]
-    }
+            'tljh-config = tljh.config:main',
+        ],
+    },
 )

tljh/config.py

@@ -157,6 +157,7 @@ def reload_component(component):
         print('Hub reload with new configuration complete')
     elif component == 'proxy':
         systemd.restart_service('configurable-http-proxy')
+        systemd.restart_service('traefik')
         print('Proxy reload with new configuration complete')
 
 
@@ -238,5 +239,6 @@ def main():
     elif args.action == 'reload':
         reload_component(args.component)
     
+
 if __name__ == '__main__':
     main()

tljh/configurer.py

@@ -7,6 +7,13 @@ be called many times per lifetime of a jupyterhub.
 Traitlets that modify the startup of JupyterHub should not be here.
 FIXME: A strong feeling that JSON Schema should be involved somehow.
 """
+
+import os
+import yaml
+
+INSTALL_PREFIX = os.environ.get('TLJH_INSTALL_PREFIX', '/opt/tljh')
+CONFIG_FILE = os.path.join(INSTALL_PREFIX, 'config.yaml')
+
 # Default configuration for tljh
 # User provided config is merged into this
 default = {
@@ -19,19 +26,46 @@ default = {
     'users': {
         'allowed': [],
         'banned': [],
-        'admin': []
+        'admin': [],
     },
     'limits': {
         'memory': '1G',
-        'cpu': None
+        'cpu': None,
+    },
+    'http': {
+        'port': 80,
+    },
+    'https': {
+        'enabled': False,
+        'port': 443,
+        'tls': {
+            'cert': '',
+            'key': '',
+        },
+        'letsencrypt': {
+            'email': '',
+            'domains': [],
+        },
     },
     'user_environment': {
-        'default_app': 'classic'
-    }
-
+        'default_app': 'classic',
+    },
 }
 
 
+def load_config(config_file=CONFIG_FILE):
+    """Load the current config as a dictionary
+
+    merges overrides from config.yaml with default config
+    """
+    if os.path.exists(config_file):
+        with open(config_file) as f:
+            config_overrides = yaml.safe_load(f)
+    else:
+        config_overrides = {}
+    return _merge_dictionaries(dict(default), config_overrides)
+
+
 def apply_config(config_overrides, c):
     """
     Merge config_overrides with config defaults & apply to JupyterHub config c

tljh/installer.py

@@ -10,7 +10,7 @@ from urllib.request import urlopen, URLError
 
 from ruamel.yaml import YAML
 
-from tljh import conda, systemd, user, apt
+from tljh import conda, systemd, traefik, user, apt
 
 INSTALL_PREFIX = os.environ.get('TLJH_INSTALL_PREFIX', '/opt/tljh')
 HUB_ENV_PREFIX = os.path.join(INSTALL_PREFIX, 'hub')
@@ -110,25 +110,32 @@ def ensure_chp_package(prefix):
 
 def ensure_jupyterhub_service(prefix):
     """
-    Ensure JupyterHub & CHP Services are set up properly
+    Ensure JupyterHub Services are set up properly
     """
+
+    os.makedirs(STATE_DIR, mode=0o700, exist_ok=True)
+
     with open(os.path.join(HERE, 'systemd-units', 'jupyterhub.service')) as f:
         hub_unit_template = f.read()
 
     with open(os.path.join(HERE, 'systemd-units', 'configurable-http-proxy.service')) as f:
         proxy_unit_template = f.read()
 
+    with open(os.path.join(HERE, 'systemd-units', 'traefik.service')) as f:
+        traefik_unit_template = f.read()
+
+    traefik.ensure_traefik_config(STATE_DIR)
+
     unit_params = dict(
         python_interpreter_path=sys.executable,
         jupyterhub_config_path=os.path.join(HERE, 'jupyterhub_config.py'),
-        install_prefix=INSTALL_PREFIX
+        install_prefix=INSTALL_PREFIX,
     )
     systemd.install_unit('configurable-http-proxy.service', proxy_unit_template.format(**unit_params))
     systemd.install_unit('jupyterhub.service', hub_unit_template.format(**unit_params))
+    systemd.install_unit('traefik.service', traefik_unit_template.format(**unit_params))
     systemd.reload_daemon()
 
-    os.makedirs(STATE_DIR, mode=0o700, exist_ok=True)
-
     # Set up proxy / hub secret oken if it is not already setup
     proxy_secret_path = os.path.join(STATE_DIR, 'configurable-http-proxy.secret')
     if not os.path.exists(proxy_secret_path):
@@ -141,10 +148,12 @@ def ensure_jupyterhub_service(prefix):
     systemd.start_service('configurable-http-proxy')
     # If JupyterHub is running, we want to restart it.
     systemd.restart_service('jupyterhub')
+    systemd.restart_service('traefik')
 
-    # Mark JupyterHub & CHP to start at boot ime
+    # Mark JupyterHub & CHP to start at boot time
     systemd.enable_service('jupyterhub')
     systemd.enable_service('configurable-http-proxy')
+    systemd.enable_service('traefik')
 
 
 def ensure_jupyterhub_package(prefix):
@@ -165,6 +174,7 @@ def ensure_jupyterhub_package(prefix):
         'jupyterhub-ldapauthenticator==1.2.2',
         'oauthenticator==0.7.3',
     ])
+    traefik.ensure_traefik_binary(prefix)
 
 
 def ensure_usergroups():
@@ -252,7 +262,7 @@ def ensure_jupyterhub_running(times=4):
             urlopen('http://127.0.0.1')
             return
         except HTTPError as h:
-            if h.code in [404, 503]:
+            if h.code in [404, 502, 503]:
                 # May be transient
                 time.sleep(1)
                 continue

tljh/jupyterhub_config.py

@@ -29,8 +29,6 @@ class CustomSpawner(SystemdSpawner):
 
 c.JupyterHub.spawner_class = CustomSpawner
 
-c.JupyterHub.port = 80
-
 # Use a high port so users can try this on machines with a JupyterHub already present
 c.JupyterHub.hub_port = 15001
 

tljh/systemd-units/configurable-http-proxy.service

@@ -5,7 +5,7 @@
 After=network.target
 
 [Service]
-User=root
+User=nobody
 Restart=always
 # chp process should have no write access anywhere on disk
 ProtectHome=tmpfs
@@ -16,8 +16,8 @@ ProtectKernelTunables=yes
 ProtectKernelModules=yes
 EnvironmentFile={install_prefix}/state/configurable-http-proxy.secret
 ExecStart={install_prefix}/hub/node_modules/.bin/configurable-http-proxy \
-            --ip 0.0.0.0 \
-            --port 80 \
+            --ip 127.0.0.1 \
+            --port 15003 \
             --api-ip 127.0.0.1 \
             --api-port 15002 \
             --error-target http://127.0.0.1:15001/hub/error

tljh/systemd-units/traefik.service

@@ -0,0 +1,24 @@
+# Template file for Traefik systemd service
+# Uses simple string.format() for 'templating'
+[Unit]
+# Wait for network stack to be fully up before starting proxy
+After=network.target
+
+[Service]
+User=root
+Restart=always
+# process only needs to write state/acme.json file, no other files
+ProtectHome=tmpfs
+ProtectSystem=strict
+PrivateTmp=yes
+PrivateDevices=yes
+ProtectKernelTunables=yes
+ProtectKernelModules=yes
+ReadWritePaths={install_prefix}/state/acme.json
+WorkingDirectory={install_prefix}/state
+ExecStart={install_prefix}/hub/bin/traefik \
+            -c {install_prefix}/state/traefik.toml
+
+[Install]
+# Start service when system boots
+WantedBy=multi-user.target

tljh/traefik.py

@@ -0,0 +1,84 @@
+"""Traefik installation and setup"""
+import hashlib
+import os
+from urllib.request import urlretrieve
+
+from jinja2 import Environment, Template
+
+from tljh.configurer import load_config
+
+# FIXME: support more than one platform here
+plat = "linux-amd64"
+traefik_version = "1.6.5"
+
+# record sha256 hashes for supported platforms here
+checksums = {
+    "linux-amd64": "9e77c7664e316953e3f5463c323dffeeecbb35d0b1db7fb49f52e1d9464ca193"
+}
+
+
+def checksum_file(path):
+    """Compute the sha256 checksum of a path"""
+    hasher = hashlib.sha256()
+    with open(path, "rb") as f:
+        for chunk in iter(lambda: f.read(4096), b""):
+            hasher.update(chunk)
+    return hasher.hexdigest()
+
+
+def ensure_traefik_binary(prefix):
+    """Download and install the traefik binary"""
+    traefik_bin = os.path.join(prefix, "bin", "traefik")
+    if os.path.exists(traefik_bin):
+        checksum = checksum_file(traefik_bin)
+        if checksum == checksums[plat]:
+            # already have the right binary
+            # ensure permissions and we're done
+            os.chmod(traefik_bin, 0o755)
+            return
+        else:
+            print(f"checksum mismatch on {traefik_bin}")
+            os.remove(traefik_bin)
+
+    traefik_url = (
+        "https://github.com/containous/traefik/releases"
+        f"/download/v{traefik_version}/traefik_{plat}"
+    )
+    print(f"Downloading traefik {traefik_version}...")
+    # download the file
+    urlretrieve(traefik_url, traefik_bin)
+    os.chmod(traefik_bin, 0o755)
+
+    # verify that we got what we expected
+    checksum = checksum_file(traefik_bin)
+    if checksum != checksums[plat]:
+        raise IOError(f"Checksum failed {traefik_bin}: {checksum} != {checksums[plat]}")
+
+
+def ensure_traefik_config(state_dir):
+    """Render the traefik.toml config file"""
+    config = load_config()
+    with open(os.path.join(os.path.dirname(__file__), "traefik.toml.tpl")) as f:
+        template = Template(f.read())
+    new_toml = template.render(config)
+    https = config["https"]
+    letsencrypt = https["letsencrypt"]
+    tls = https["tls"]
+    # validate https config
+    if https["enabled"]:
+        if not tls["cert"] and not letsencrypt["email"]:
+            raise ValueError(
+                "To enable https, you must set tls.cert+key or letsencrypt.email+domains"
+            )
+        if (letsencrypt["email"] and not letsencrypt["domains"]) or (
+            letsencrypt["domains"] and not letsencrypt["email"]
+        ):
+            raise ValueError("Both email and domains must be set for letsencrypt")
+    with open(os.path.join(state_dir, "traefik.toml"), "w") as f:
+        os.fchmod(f.fileno(), 0o744)
+        f.write(new_toml)
+
+    # ensure acme.json exists and is private
+    with open(os.path.join(state_dir, "acme.json"), "a") as f:
+        os.fchmod(f.fileno(), 0o600)
+

tljh/traefik.toml.tpl

@@ -0,0 +1,69 @@
+# traefik.toml file template
+{% if https['enabled'] %}
+defaultEntryPoints = ["http", "https"]
+{% else %}
+defaultEntryPoints = ["http"]
+{% endif %}
+
+logLevel = "INFO"
+# log errors, which could be proxy errors
+[accessLog]
+format = "json"
+[accessLog.filters]
+statusCodes = ["500-999"]
+
+[accessLog.fields.headers]
+[accessLog.fields.headers.names]
+Authorization = "redact"
+Cookie = "redact"
+Set-Cookie = "redact"
+X-Xsrftoken = "redact"
+
+[respondingTimeouts]
+idleTimeout = "10m0s"
+
+[entryPoints]
+  [entryPoints.http]
+  address = ":{{http['port']}}"
+  {% if https['enabled'] %}
+    [entryPoints.http.redirect]
+    entryPoint = "https"
+  {% endif %}
+
+  {% if https['enabled'] %}
+  [entryPoints.https]
+  address = ":{{https['port']}}"
+  backend = "jupyterhub"
+  [entryPoints.https.tls]
+  {% if https['tls']['cert'] %}
+    [[entryPoints.https.tls.certificates]]
+      certFile = "{{https['tls']['cert']}}"
+      keyFile = "{{https['tls']['key']}}"
+  {% endif %}
+  {% endif %}
+
+{% if https['enabled'] and https['letsencrypt']['email'] %}
+[acme]
+email = "{{https['letsencrypt']['email']}}"
+storage = "acme.json"
+entryPoint = "https"
+  [acme.httpChallenge]
+  entryPoint = "http"
+
+{% for domain in https['letsencrypt']['domains'] %}
+[[acme.domains]]
+  main = "{{domain}}"
+{% endfor %}
+{% endif %}
+
+[file]
+
+[frontends]
+  [frontends.jupyterhub]
+  backend = "jupyterhub"
+  passHostHeader = true
+[backends]
+  [backends.jupyterhub]
+    [backends.jupyterhub.servers.chp]
+    url = "http://127.0.0.1:15003"
+