user env: only upgrade jupyterhub in user env when upgrading tljh

tljh/installer.py

@@ -200,6 +200,8 @@ def ensure_user_environment(user_requirements_txt_file):
 
     # Case 1: no existing environment
     if not package_versions:
+        is_fresh_install = True
+
         # 1a. no environment, but prefix exists.
         # Abort to avoid clobbering something we don't recognize
         if os.path.exists(USER_ENV_PREFIX) and os.listdir(USER_ENV_PREFIX):
@@ -219,6 +221,8 @@ def ensure_user_environment(user_requirements_txt_file):
         # quick sanity check: we should have conda and mamba!
         assert "conda" in package_versions
         assert "mamba" in package_versions
+    else:
+        is_fresh_install = False
 
     # next, check Python
     python_version = package_versions["python"]
@@ -259,9 +263,15 @@ def ensure_user_environment(user_requirements_txt_file):
 
     conda.ensure_pip_requirements(
         USER_ENV_PREFIX,
-        os.path.join(HERE, "requirements-base.txt"),
+        os.path.join(HERE, "requirements-user-env.txt"),
         upgrade=True,
     )
+    if is_fresh_install:
+        conda.ensure_pip_requirements(
+            USER_ENV_PREFIX,
+            os.path.join(HERE, "requirements-user-env-extras.txt"),
+            upgrade=True,
+        )
 
     if user_requirements_txt_file:
         # FIXME: This currently fails hard, should fail soft and not abort installer

tljh/requirements-user-env-extras.txt

@@ -1,14 +1,14 @@
 # When tljh.installer runs, the users' environment as typically found in
-# /opt/tljh/user, is setup with these packages.
+# /opt/tljh/user, is installed with these packages.
+#
+# Whats listed here represents additional packages that the distributions
+# installs initially, but doesn't upgrade as tljh is upgraded.
 #
 # WARNING: The order of these dependencies matters, this was observed when using
 #          the requirements-txt-fixer pre-commit hook that sorted them and made
 #          our integration tests fail.
 #
-# JupyterHub + notebook package are base requirements for user environment
-jupyterhub==4.*
 notebook==6.*
-# Install additional notebook frontends!
 jupyterlab==3.*
 # nbgitpuller for easily pulling in Git repositories
 nbgitpuller==1.*

tljh/requirements-user-env.txt

@@ -0,0 +1,7 @@
+# When tljh.installer runs, the users' environment as typically found in
+# /opt/tljh/user, is installed or upgraded with these packages.
+#
+# Whats listed here should be only the unconditional requirements that we have in
+# the user environment.
+#
+jupyterhub==4.*