Need a way to access local host ports when running in dev

Jjulian7797 Need a way to access local host ports when running in dev

kian•9/16/25, 9:32 PM

Use host.docker.internalhost.docker.internal - localhostlocalhost to a container is just itself rather than your host machine.

julian7797OP•9/16/25, 9:32 PM

thx

julian7797OP•9/16/25, 9:32 PM

Skill issue on my part

julian7797OP•9/16/25, 9:32 PM

appreciate the assist

kian•9/16/25, 9:32 PM

I think there is some Docker network modes where you can use localhostlocalhost but for the default host.docker.internalhost.docker.internal is the way

julian7797OP•9/16/25, 9:34 PM

Cool, also would love to see Hyperdrive support inside the containers

julian7797OP•9/16/25, 9:34 PM

I think it might already be in a feature request

kian•9/16/25, 9:39 PM

It's on our radar but no ETA - you can follow this GitHub issue for updates: https://github.com/cloudflare/workers-sdk/issues/10320

GitHub

feature: connect to hyperdrive from inside a container · Issue #10...

What versions & operating system are you using? System: OS: macOS 15.5 CPU: (8) arm64 Apple M3 Memory: 120.78 MB / 16.00 GB Shell: 5.9 - /bin/zsh Binaries: Node: 24.2.0 - /opt/homebrew/bin/node...

julian7797OP•9/16/25, 11:53 PM

Probably missing a config option or something but i have zero logs showing up for my container, and its definitely getting hit bc i see memory, cpu, etc increasing for requests

Jjulian7797 Probably missing a config option or something but i have zero logs showing up fo...

julian7797OP•9/17/25, 12:00 AM

deleted and recreated, logs showing up now

TangoBee•9/17/25, 12:13 PM

Hi,
I'm using containers locally with npx wrangler dev, but I don't see any logs that I have added in my container code in the terminal.

China•9/17/25, 6:08 PM

Hi everyone,

I'm using Wrangler to deploy a project that's currently configured with a container. The issue is that even when there are no code changes in the container, every time I run wrangler deploy, it rebuilds the container image and pushes it, which takes a lot of time and resources.

Does anyone know if it's possible to use wrangler deploy to update the worker without rebuilding and pushing the container every time?

julian7797OP•9/17/25, 8:26 PM

Are custom container instance types still up to date in docs? Tried setting according to here: https://developers.cloudflare.com/workers/wrangler/configuration/#custom-instance-types but getting a validate input error while deploying (have an enterprise account)

Cloudflare Docs

Configuration

Use a configuration file to customize the development and deployment setup for your Worker project and other Developer Platform products.

bro14•9/18/25, 1:08 PM

hello does anyone knows how to fix this X [ERROR] You don't have 'containers:write' in your list of scopes i've already added permission on my API TOKEN to edit containers(i don't think there's write option)

updating to latest wrangler works

blyedev•9/19/25, 2:39 AM

Hi everyone quick question. Would it be possible to use hyperdrive with containers?

zerozerozeroone•9/19/25, 3:37 AM

Do or can containers run in a single location?
If containers are idle are they stopped?
Are idle containers that still run but aren’t serving anything still consuming cpu resources?

Bblyedev Hi everyone quick question. Would it be possible to use hyperdrive with containe...

Chaika•9/19/25, 3:44 AM

it's on the roadmap but not yet containers-beta

blyedev•9/19/25, 3:45 AM

It really is great to see that everything I ever need consistently is one the roadmap haha

Chaika•9/19/25, 3:45 AM

soon^tm

Zzerozerozeroone Do or can containers run in a single location? If containers are idle are they s...

Chaika•9/19/25, 3:50 AM

The docs answer those well:
https://developers.cloudflare.com/containers/pricing/
https://developers.cloudflare.com/containers/faq/

Location selection in the faq, if you're just asking about placement
idle is handled by the containers library, the sleepAfter setting which defaults to 10m without any activity/requests

You only pay for what you use — charges start when a request is sent to the container or when it is manually started. Charges stop after the container instance goes to sleep, which can happen automatically after a timeout. This makes it easy to scale to zero, and allows you to get high utilization even with bursty traffic.

TangoBee•9/19/25, 5:56 AM

Hi,
Can we run apache kafka in cloudflare containers?

TangoBee•9/19/25, 5:59 AM

So, I'll be having 3 services. One service will push data to Kafka, and another service will consume that data from Kafka. Is it possible to deploy all three services in one Cloudflare container?

bro14•9/19/25, 8:59 AM

Hello anyone who have tried pulling image from external registry like gcp artifac registry is this possible in cf container?
wrangler.toml
[[containers]]
class_name = "sample"
image = "europe-west-docker.pkg.dev/...."

Bbro14 Hello anyone who have tried pulling image from external registry like gcp artifa...

mcanaleta•9/19/25, 1:19 PM

By the documentation "Currently, all images must use registry.cloudflare.com, which is the default registry for Wrangler." (https://developers.cloudflare.com/containers/image-management/#using-existing-images) so you have to pull & push to cloudflare registry

Cloudflare Docs

Image Management

When running wrangler deploy, if you set the image attribute in you Wrangler configuration
file to a path, wrangler will build your container image locally using Docker, then push it to a registry run by Cloudflare.
This registry is integrated with your Cloudflare account and is backed by R2. All authentication is handled automatically by
Cloudf...

Mmcanaleta By the documentation "Currently, all images must use registry.cloudflare.com, wh...

bro14•9/19/25, 1:21 PM

ahh i see, thank you for responding

kian•9/19/25, 1:24 PM

Yeah - currently pull it locally and push it up to our registry.

kian•9/19/25, 1:24 PM

External registry support is being worked on as mentioned in the docs aside - basically pullthrough so we do the pull + push for you.

Kkian <https://github.com/cloudflare/templates/tree/main/containers-template> is proba...

Steps•9/19/25, 6:22 PM

That is the "most simple"? It's pretty complex.

To be honest, it looks more like a testbed than a minimalistic "get you started" template.

Steps•9/19/25, 9:12 PM

Ok, I made the simple example I was looking for myself after some trial and error.

https://github.com/StefanOltmann/kotlin-cloudflare-containers-sample

Steps•9/19/25, 9:19 PM

Is Cloudflare open to contributions?
I could send that as a PR to https://github.com/cloudflare/templates/tree/main ...

SSteps Is Cloudflare open to contributions? I could send that as a PR to https://github...

blyedev•9/20/25, 1:46 PM

As far as I remember their contribution guide said they very much are but have certain requirements.

blyedev•9/20/25, 1:47 PM

Ngl I'd love if they had like a keycloak deployment in templates, would be incredible to just deploy sso with minimal config

Steps•9/21/25, 8:11 PM

What can cause Container suddenly disconnected, try againContainer suddenly disconnected, try againafter ~10s ? Is that a response timeout?

Steps•9/21/25, 8:39 PM

On the highest instance type my POST request is successful in 100 ms, but the response is still HTTP 500

Steps•9/21/25, 8:40 PM

It has the structure like here: https://github.com/StefanOltmann/kotlin-cloudflare-containers-sample/

Just with a POST instead of a GET.

Does that make a difference?

CodingCoop | Co-Founder Nullshot•9/22/25, 10:13 AM

I'm running some applications simialr to the sandbox sdk. To get an nodejs app started in dev mode, it's taking ~3 minutes which isn't bad, but there are CPU intensive operations when dynamically downloading code in a sandbox. I think .5 CPU is not enough and ideally I'd want to burst up to 2 vCPU if not dedicated.

Sent my feedback, but I think 2 vCPU + 8gb Memory is where my sweet spot will be 16 Gb memory for more intensive apps like games and a GPU for all my use cases which I assume is far out.

CodingCoop | Co-Founder Nullshot•9/22/25, 10:14 AM

https://github.com/cloudflare/sandbox-sdk <== for those who haven't found this gem

GitHub

GitHub - cloudflare/sandbox-sdk: Run sandboxed code environments on...

Run sandboxed code environments on Cloudflare's edge network - cloudflare/sandbox-sdk

Rui Hayashi•9/22/25, 1:06 PM

How can I set a container directly through the Cloudflare API? Is this documented somewhere? Having a look at wrangler's code, it seems there is a /applications endpoint (https://github.com/cloudflare/workers-sdk/blob/main/packages/containers-shared/src/client/services/ApplicationsService.ts#L44), but when I try to call it I get a "No route for that URI" error.

GitHub

workers-sdk/packages/containers-shared/src/client/services/Applicat...

Home to Wrangler, the CLI for Cloudflare Workers® - cloudflare/workers-sdk

workers-sdk/packages/containers-shared/src/client/services/Applicat...

RRui Hayashi How can I set a container directly through the Cloudflare API? Is this documente...

John Spurlock•9/22/25, 1:16 PM

all of those endpoints are prefixed by /containers/containers

JJohn Spurlock all of those endpoints are prefixed by `/containers`

Rui Hayashi•9/22/25, 1:29 PM

that worked, thanks for the help (do you know whether this is documented somewhere?)

RRui Hayashi that worked, thanks for the help (do you know whether this is documented somewhe...

John Spurlock•9/22/25, 1:40 PM

I don't believe it is, although I wish it was. In case it helps, here is a client api I wrote against it - same as you, just based on poking through wrangler

https://github.com/skymethod/denoflare/blob/f46183514877db55d1fff21a9eb0055fa09ae827/common/cloudflare_api.ts#L2586

Steps•9/22/25, 3:42 PM

For Cloudflare Containers the included usage is 375 vCPU-minutes/month ...
That means the small "dev" instance with 1/16 vCPU can run for 6000 minutes/month, which are roughly 4 days. Is that math correct?

If I set "sleepAfter" to "0" this bascially means that every call to the container will be a 2-3 second cold start, right?

My service gets a call every 20 seconds. So if I set the timeout to 30 seconds, it will be active all the time and burn through the quota with reaching the limit after 4 days... is that correct?

Or will it still be considerably fast when sleeping?

An AWS lambda has a nasty cold start of 2-3 seconds, too, but after that it's "warm" for about 10 to 15 minutes... But I only need to pay the actual usage time, not the time it's idling.

Did I get that right about the difference between a AWS Lambda and an Cloudflare Container?

Vvilvei AWS Lambda is a function service, that can be called using http via their apigat...

pandalambda2•9/23/25, 8:15 AM

the OP is probably using lambda layers then architecturally its almost identical

Vvilvei AWS Lambda is a function service, that can be called using http via their apigat...

Steps•9/23/25, 6:48 PM

Yes, AWS API gateway is pricy. I use the HTTP Function URLs - they are free.

Vvilvei If you know you are receiving a call every 20 seconds, then you could create Dur...

Steps•9/23/25, 6:50 PM

My question is not so much about how to avoid the cold start... it's about the billable duration.

The difference is that idle time on Containers cost while the time an AWS lambda stays warm after invocation doesn't, right?

If I set set the cointainer sleep to 0, will every call be a cold start or will it stay warm for a while?

SSteps My question is not so much about how to avoid the cold start... it's about the b...

gruntlord6•9/23/25, 11:45 PM

thats more comparable to a durable object then a container

pandalambda2•9/24/25, 1:33 AM

So the new about capnweb dropped, and it's powering wrangler local<>remote services in dev mode, i.e. it can communicate with Cloudflare services remotely and this is powered by capnweb protocol, so things like kv, worker bindings, queues etc.. are no longer restricted to workers, so I guess in theory if one digs into the source code for wrangler, we could use the same code to allow direct communicate from containers. My question is are you planning to drop a few SDKs for this - node initially, java, dotnet, go, rust? And secondly is this on the short term horizon perhaps this birthday week?

pandalambda2•9/24/25, 1:34 AM

ref: https://blog.cloudflare.com/capnweb-javascript-rpc-library/#try-it-out (the bottom bit about remote bindings)...

The Cloudflare Blog

Cap'n Web: A new RPC system for browsers and web servers

Cap'n Web is a new open source, JavaScript-native RPC protocol for use in browsers and web servers. It provides the expressive power of Cap'n Proto, but with no schemas and no boilerplate.

Need a way to access local host ports when running in dev

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