Use venv for base hub environment

- TLJH should support raspberry pi, which runs ARM. conda does
  not support ARM.
- Get nodejs from nodesource instead of conda or default repositories.
  Default repositories get out of date pretty quickly.
- Install CHP from npm

tljh/installer.py

@@ -9,7 +9,7 @@ from urllib.request import urlopen, URLError
 
 from ruamel.yaml import YAML
 
-from tljh import conda, systemd, user
+from tljh import conda, systemd, user, apt
 
 INSTALL_PREFIX = os.environ.get('TLJH_INSTALL_PREFIX', '/opt/tljh')
 HUB_ENV_PREFIX = os.path.join(INSTALL_PREFIX, 'hub')
@@ -21,6 +21,79 @@ HERE = os.path.abspath(os.path.dirname(__file__))
 rt_yaml = YAML()
 
 
+def ensure_node():
+    """
+    Ensure nodejs from nodesource is installed
+    """
+    key = b"""
+-----BEGIN PGP PUBLIC KEY BLOCK-----
+Version: GnuPG v1
+Comment: GPGTools - https://gpgtools.org
+
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+=CLGF
+-----END PGP PUBLIC KEY BLOCK-----
+    """.strip()
+    apt.trust_gpg_key(key)
+    apt.add_source('nodesource', f'https://deb.nodesource.com/node_10.x', 'main')
+    apt.install_packages(['nodejs'])
+
+
+def ensure_chp_package(prefix):
+    """
+    Ensure CHP is installed
+    """
+    if not os.path.exists(os.path.join(prefix, 'node_modules', '.bin', 'configurable-http-proxy')):
+        subprocess.check_call([
+            'npm', 'install', 'configurable-http-proxy@3.1.0'
+        ], cwd=prefix)
+
+
 def ensure_jupyterhub_service(prefix):
     """
     Ensure JupyterHub & CHP Services are set up properly
@@ -70,7 +143,6 @@ def ensure_jupyterhub_package(prefix):
     hub environment be installed with pip prevents accidental mixing of python
     and conda packages!
     """
-    conda.ensure_conda_packages(prefix, ['configurable-http-proxy==3.1.0'])
     conda.ensure_pip_packages(prefix, [
         'jupyterhub==0.9.1',
         'jupyterhub-dummyauthenticator==0.3.1',
@@ -103,7 +175,14 @@ def ensure_user_environment(user_requirements_txt_file):
     Set up user conda environment with required packages
     """
     print("Setting up user environment...")
-    conda.ensure_conda_env(USER_ENV_PREFIX)
+    miniconda_version = '4.5.4'
+    miniconda_installer_md5 = "a946ea1d0c4a642ddf0c3a26a18bb16d"
+
+    if not conda.check_miniconda_version(USER_ENV_PREFIX, miniconda_version):
+        print('Downloading & setting up user environment...')
+        with conda.download_miniconda_installer(miniconda_version, miniconda_installer_md5) as installer_path:
+            conda.install_miniconda(installer_path, USER_ENV_PREFIX)
+
     conda.ensure_conda_packages(USER_ENV_PREFIX, [
         # Conda's latest version is on conda much more so than on PyPI.
         'conda==4.5.8'
@@ -194,12 +273,11 @@ def main():
 
     ensure_usergroups()
     ensure_user_environment(args.user_requirements_txt_url)
-    # Weird setuptools issue creates a few world-writable metadata files.
-    # Fix it:
-    subprocess.check_call(["chmod", "-R", "o-w", os.path.join(HUB_ENV_PREFIX, "pkgs")])
 
     print("Setting up JupyterHub...")
+    ensure_node()
     ensure_jupyterhub_package(HUB_ENV_PREFIX)
+    ensure_chp_package(HUB_ENV_PREFIX)
     ensure_jupyterhub_service(HUB_ENV_PREFIX)
     ensure_jupyterhub_running()