Solara•2y ago

Aren't all these the responsibility of the browser to fetch stuff from the CDN?

Good afternoon! Can Solara run on a read-only file system? I tried running it on AWS Lambda and it crashed here: https://github.com/widgetti/solara/blob/master/solara/server/settings.py#L159C4-L159C4

GitHub

solara/solara/server/settings.py at master · widgetti/solara

A Pure Python, React-style Framework for Scaling Your Jupyter and Web Apps - widgetti/solara

17 Replies

taltimes2OP•2y ago

What if there are 2 instances of the server? Or 20? Where is this directory? What if the server is containerized?

MaartenBreddels•2y ago

I just had the same issue, and I have a fix locally, really a coincidence you hit the same 🙂 yes, you can turn off the cdn proxy, for that purpose I'll push a fix with documentation on this soon you could open an issue if you want to track it

taltimes2OP•2y ago

awesome! Is it a small patch I can apply tonight?

MaartenBreddels•2y ago

yeah

diff --git a/solara/server/settings.py b/solara/server/settings.py
index fdcbd3d..046f7a7 100644
--- a/solara/server/settings.py
+++ b/solara/server/settings.py
@@ -152,7 +152,12 @@ assets = Assets()
 oauth = OAuth()
 session = Session()
 
-assets.proxy_cache_dir.mkdir(exist_ok=True, parents=True)
+try:
+    assets.proxy_cache_dir.mkdir(exist_ok=True, parents=True)
+except PermissionError:
+    # that's ok, the user probably doesn't have permission to create the directory
+    # in this case, we would need to install solara-assets?
+    pass
 
 if telemetry.server_user_id == "not_set":
     home = get_solara_home()
diff --git a/solara/server/starlette.py b/solara/server/starlette.py
index e12fa69..ea61198 100644
--- a/solara/server/starlette.py
+++ b/solara/server/starlette.py
@@ -381,7 +381,7 @@ routes = [
     Route("/", endpoint=root),
     Route("/{fullpath}", endpoint=root),
     Route("/_solara/api/close/{connection_id}", endpoint=close, methods=["POST"]),
-    Mount(f"/{cdn_url_path}", app=StaticCdn(directory=settings.assets.proxy_cache_dir)),
+    *([Mount(f"/{cdn_url_path}", app=StaticCdn(directory=settings.assets.proxy_cache_dir))] if settings.assets.proxy_cache_dir.exists() else []),
     Mount(f"{prefix}/static/public", app=StaticPublic()),
     Mount(f"{prefix}/static/assets", app=StaticAssets()),
     Mount(f"{prefix}/static/nbextensions", app=StaticNbFiles()),

diff --git a/solara/server/settings.py b/solara/server/settings.py
index fdcbd3d..046f7a7 100644
--- a/solara/server/settings.py
+++ b/solara/server/settings.py
@@ -152,7 +152,12 @@ assets = Assets()
 oauth = OAuth()
 session = Session()
 
-assets.proxy_cache_dir.mkdir(exist_ok=True, parents=True)
+try:
+    assets.proxy_cache_dir.mkdir(exist_ok=True, parents=True)
+except PermissionError:
+    # that's ok, the user probably doesn't have permission to create the directory
+    # in this case, we would need to install solara-assets?
+    pass
 
 if telemetry.server_user_id == "not_set":
     home = get_solara_home()
diff --git a/solara/server/starlette.py b/solara/server/starlette.py
index e12fa69..ea61198 100644
--- a/solara/server/starlette.py
+++ b/solara/server/starlette.py
@@ -381,7 +381,7 @@ routes = [
     Route("/", endpoint=root),
     Route("/{fullpath}", endpoint=root),
     Route("/_solara/api/close/{connection_id}", endpoint=close, methods=["POST"]),
-    Mount(f"/{cdn_url_path}", app=StaticCdn(directory=settings.assets.proxy_cache_dir)),
+    *([Mount(f"/{cdn_url_path}", app=StaticCdn(directory=settings.assets.proxy_cache_dir))] if settings.assets.proxy_cache_dir.exists() else []),
     Mount(f"{prefix}/static/public", app=StaticPublic()),
     Mount(f"{prefix}/static/assets", app=StaticAssets()),
     Mount(f"{prefix}/static/nbextensions", app=StaticNbFiles()),

and use export SOLARA_ASSETS_PROXY=False this is my local diff, i want to do it slightly differently when we detect we cannot write, to give a warning to tell what is going on, and then we automatically turn off the proxy, so it works out of the box

taltimes2OP•2y ago

cool thanks! btw - I had an OSError and not a PermissionError - you can create a tuple of exceptions 2023-07-17T12:36:56.731+00:00 [ERROR] OSError: [Errno 30] Read-only file system: '/var/lang/share/solara'

MaartenBreddels•2y ago

oh, thank you, that's helpful, i'll add that

taltimes2OP•2y ago

Can you please let us know when you push the fix?

MaartenBreddels•2y ago

do you want to review this? https://github.com/widgetti/solara/pull/211 and maybe test it?

GitHub

feat: when the proxy cache dir cannot be written to, disable the pr...

This will let solara work out of the box when the proxy cache dir is not writable, and will not require the user to manually disable the proxy. If the proxy is disabled, the cache dir will not be c...

taltimes2OP•2y ago

except Exception as e: ? 🥲 do I still need to set an environment variable?

MaartenBreddels•2y ago

you don't like us catching all exception? 🙂 at least we're not catching BaseException 🙂 but, given that you had an OSError, and I had a PermissionError, i guess there are more we don't know about you wouldn't need to set an envirioment variable, you will get a warning though

taltimes2OP•2y ago

sure, but the way to catch them is by NOT specifying them until they happen... testing now

MaartenBreddels•2y ago

i'm not sure i follow you, can you elaborate, feel free to use github as well if you prefer that happy to learn here 🙂

taltimes2OP•2y ago

I'm not afraid of exceptions - they are informative and the backtrace tells you a lot of the information you need to debug them. except Exception catches even syntax mistakes (!) I would just have used except (OSError, PermissionError) as e and the worst thing that can happen is that you learn about another type of exception in some other system. It's a single line, but it's still Python and a lot of things can go wrong. What if there's no proxy_cache_dir in assets? What if mkdir on some system need different parameters? Doesn't this crash for you: with FileLock(str(server_user_id_file) + ".lock"): (line 172 in settings.py) ?

MaartenBreddels•2y ago

i agree in general not to catch Exception, but not on trivial lines line this, it's a trade off between catching everything, and not catching enough (especially with files, i've been bitten by not knowing which exceptions are possible) no, my home dir is writable, that also fails for you? what is the exception?

taltimes2OP•2y ago

2023-07-18T15:06:59.259+00:00 [ERROR] OSError: [Errno 30] Read-only file system: '/var/task/server_user_id.txt.lock'

  File "/var/task/solara/server/settings.py", line 172, in <module>
                                     with FileLock(str(server_user_id_file) + ".lock"):

MaartenBreddels•2y ago

https://docs.python.org/3/library/exceptions.html#os-exceptions i take it back, they are all OSErrors!

Python documentation

Built-in Exceptions

In Python, all exceptions must be instances of a class that derives from BaseException. In a try statement with an except clause that mentions a particular class, that clause also handles any excep...

MaartenBreddels•2y ago

will also fix that error

Gaming

Programming

Aren't all these the responsibility of the browser to fetch stuff from the CDN?