I'm new to both Docker and Azure Functions so it must be a silly question...
You can pull the images of Azure Functions from Docker Hub, like:
docker pull mcr.microsoft.com/azure-functions/node:3.0-node12
Now I pulled the image of a specific runtime of Azure Functions, but what can I do with this exactly?
First I thought I could find Azure Functions Core Tools inside of the container, then found the azure-function-host directory with bunch of files, but I'm not sure what it is.
docker exec -it "TheContainerMadeOfAzureFunctionsImage" bash
-> FuncExtensionBundles azure-functions-host bin boot dev etc home lib lib64 media mnt opt proc root run sbin srv sys tmp usr var
Thank you in advance.
You can install the remote development extension tools for VSCode and the Azure Functions extension.
Create your local folder then using the remote development tools, open that folder inside a container from the command pallette by selecting 'Reopen In Container'
Reopen In Container Image
Then select your definition.
Remote Dev Tools Image
This actually use those base images you mentioned.
It will create a .devcontainer hidden directory in your repo where it stores the container information and saves you having to install the Function Core tools/NPM or anything else on your local machine.
It automatically forwards the required ports for local debugging and you can push the devcontainer definitions to source control so that others can use your definition with the project.
Last week I solved it myself. I found the exact image in Docker Hub, then docker pull mcr.microsoft.com/azure-functions/node:3.0-node12-core-tools and that's it.
You can find a full list of available tags for each runtime.
In container you can run both Azure Functions Core Tools and a language runtime (like Node.js or Python, etc.) and of course you can create function apps.
With port-forwarding like docker run -it -p 8080:7071 --name container1 mcr.microsoft.com/azure-functions/node:3.0-node12-core-tools bash you can debug your functions running inside a container (which uses port 7071) from your local machine, by sending HTTP requests to localhost:8080. This is somewhat brute force but I'm happy.
Related
I've got a python package running in a container.
Is it best practice to install it in /opt/myapp within the container?
Should the logs go in /var/opt/myapp?
Should the config files go in /etc/opt/myapp?
Is anyone recommending writing logs and config files to /opt/myapp/var/log and /opt/myapp/config?
I notice google chrome was installed in /opt/google/chrome on my (host) system, but it didn't place any configs in /etc/opt/...
Is it best practice to install it in /opt/myapp within the container?
I place my apps in my container images in /app. So in the dockerfile I do
WORKDIR /app at the beginning
Should the logs go in /var/opt/myapp?
In container world the best practice is that your application logs go into stdout, stderr and not into files inside the container because containers are ephemeral by design and should be treated that way so when a container is stopped and deleted all of its data on its filesystem is gone.
On local docker development environment you can see the logs with docker logs and you can:
start a container named gettingstarted from the image docker/getting-started:
docker run --name gettingstarted -d -p 80:80 docker/getting-started
redirect docker logs output to a local file on the docker client (your machine from where you run the docker commands):
docker logs -f gettingstarted &> gettingstarted.log &
open http://localhost to generate some logs
read the log file with tail realtime or with any text viewer program:
tail -f gettingstarted.log
Should the config files go in /etc/opt/myapp?
Again, you can put the config files anywhere you want, I like to keep them together with my app so in the /app directory, but you should not modify the config files once the container is running. What you should do is instead pass the config variables to the container as environment variables at startup with the -e flag, for example to create MYVAR variable with MYVALUE value inside the container start it this way:
docker run --name gettingstarted -d -p 80:80 -e MYVAR='MYVALUE' docker/getting-started
exec into the container to see the variable:
docker exec -it gettingstarted sh
/ # echo $MYVAR
MYVALUE
From here it is the responsibility of your containerized app to understand these variables and translate them to actual application configurations. Some/most programming languages support reaching env vars from inside the code at runtime but if this is not an option then you can do an entrypoint.sh script that updates the config files with the values supplied through the env vars. A good example for this is the postgresql entrypoint: https://github.com/docker-library/postgres/blob/master/docker-entrypoint.sh
Is anyone recommending writing logs and config files to
/opt/myapp/var/log and /opt/myapp/config?
As you can see, it is not recommended to write logs into the filesystem of the container you would rather have a solution to save them outside of the container if you need them persisted.
If you understand and follow this mindset especially that containers are ephemeral then it will be much easier for you to transition from the local docker development to production ready kubernetes infrastructures.
Docker is Linux, so almost all of your concerns are related to the best operative system in the world: Linux
Installation folder
This will help you:
Where to install programs on Linux?
Where should I put software I compile myself?
and this: Linux File Hierarchy Structure
As a summary, in Linux you could use any folder for your apps, bearing in mind:
Don't use system folders : /bin /usr/bin /boot /proc /lib
Don't use file system folder: /media / mnt
Don't use /tmp folder because it's content is deleted on each restart
As you researched, you could imitate chrome and use /opt
You could create your own folder like /acme if there are several developers entering to the machine, so you could tell them: "No matter the machine or the application, all the custom content of our company will be in /acme". Also this help you if you are a security paranoid because will be able to guess where your application is. Any way, if the devil has access to your machine, is just a matter of time to find all.
You could use fine grained permissions to keep safe the chosen folder
Log Folder
Similar to the previous paragraph:
You could store your logs the standard /var/log/acme.log
Or create your own company standard
/acme/log/api.log
/acme/webs/web1/app.log
Config Folder
This is the key for devops.
In a traditional, ancient and manually deployments, some folders were used to store the apps configurations like:
/etc
$HOME/.acme/settings.json
But in the modern epoch and if you are using Docker, you should not store manually your settings inside of container or in the host. The best way to have just one build and deploy n times (dev, test, staging, uat, prod, etc) is using environment variables.
One build , n deploys and env variables usage are fundamental for devops and cloud applications, Check the famous https://12factor.net/
III. Config: Store config in the environment
V. Build, release, run: Strictly separate build and run stages
And also is a good practice on any language. Check this Heroku: Configuration and Config Vars
So your python app should not read or expect a file in the filesystem to load its configurations. Maybe for dev, but no for test and prod.
Your python should read its configurations from env variables
import os
print(os.environ['DATABASE_PASSWORD'])
And then inject these values at runtime:
docker run -it -p 8080:80 -e DATABASE_PASSWORD=changeme my_python_app
And in your developer localhost,
export DATABASE_PASSWORD=changeme
python myapp.py
Before the run of your application and in the same shell
Config of a lot pf apps
The previous approach is an option for a couple of apps. But if you are driven to microservices and microfrontends, you will have dozens of apps on several languages. So in this case, to centralize the configurations you could use:
spring cloud
zookeeper
https://www.vaultproject.io/
https://www.doppler.com/
Or the Configurator (I'm the author)
I am trying to mount a folder of the host machine to docker container but without success. I have the following setup:
Windows machine
From 1 I access linux server
On 2 I create a docker container that should be able to access files on 1
In the dockerfile I do the following:
ADD //G/foo/boo /my_project/boo
This throws an error that the folder cannot be found, since the container tries to access the folder on linux. However, I do want the container to access the windows machine.
Ideally without copying the files from the source to target folder. I am not sure if ADD copies the files or just gives an opportunity to access files.
Volumes are designed to be attached to running containers and not to the containers used to build the docker image. In case you would like to make your running container accessing a shared file system, you need to attach the volume of the application container during the creation time. This step depends on what you are using for deploying the containers, but in case you are using docker-compose this can be done as shown below
nginxplus:
image: bhc-nginxplus
volumes:
- "${path_on_the_host}:${path_in_the_container}"
with docker commands
docker run -v ${path_on_the_host}:${path_in_the_container} $image
I have deployed .net core 3.1 project on DigitalOcean using docker. In my project inside wwwroot directory, there is an images directory where I am uploading my pictures. After uploading, I can see pictures in the browser.
But the problem is if I am building a docker project again and running it then it doesn't show the pictures which have been previously uploaded.
My docker build command is: docker build -t "jugaadhai-service" --file Dockerfile .
and docker run command is docker run -it -d -p 0.0.0.0:2900:80 jugaadhai-service
EDIT 1: After some searching I came to know that when project is running through docker then files are getting uploaded in docker's containers directory not in projects directory. That's why images are not coming on new build.
So when a docker container is created, it's an isolated virtual environment running on a host machine. If the host machine is your local computer or some host in the cloud does not really matter, it works the same way. The container is created from the build definition in the Dockerfile.
This means you can replicate this on your local environment, try build the image, upload a few images and then delete the image or create a new image with the same tag. The images are also gone then.
If you upload images or file to a container on let's say DigitalOcean, and you redeploy a new container with a different tag, the images still lives inside the old container. Same thing if you run on let's say kubernetes, if a pod/container restart has happen, again everything is lost forever and it's as if a new container was built.
This is where volumes comes in to play. So when you have persistent data you want to store, you should store them outside of the container itself. If you want to store the images on the host machine or some other network drive, you have to specify that and map it with the container.
You can find out more about it here:
https://docs.docker.com/storage/volumes/
https://docs.docker.com/storage/
https://www.youtube.com/watch?v=Nxi0CR2lCUc
https://medium.com/bb-tutorials-and-thoughts/understanding-docker-volumes-with-an-example-d898cb5e40d7
I have a running docker container with some service running inside it. Using that service, I want to pull a file from the host into the container.
docker cp won't work because that command is run from the host. I
want to trigger the copy from the container
mounting host filesystem paths into the container is not possible without stopping the container. I cannot stop the container. I can, however, install other things inside this Ubuntu container
I am not sure scp is an option since I don't have the login/password/keys to the host from the running container
Is it even possible to pull/copy a file into a container from a service running inside the container? What are my possibilities here? ftp? telnet? What are my options?
Thanks
I don't think you have many options. An idea is that if:
the host has a web server (or FTP server) up and running
and the file is located in the appropriate directory (so that it can be served)
maybe you can use wget or curl to get the file. Keep in mind that you might need credentials though...
IMHO, if what you are asking for is doable, it is a security hole.
Pass the host path as a parameter to your docker container, customize the docker image to read the file from the path(read above in parameter) and use the file as required.
You could validate the same in docker entry point script.
There is any way to download a file from google managed VM docker?
we lost one that is in production version and I want to download it to my computer but I cant find the app path
It should be possible.
First, determine the GCE instance that runs your version. The name of the version should be part of the instance name. If your version has multiple instances, you may have to try all of them (or if your file was part of the application, any of them may work).
From the Cloud console, you can switch it from "Google managed" to self-managed.
Next, use gcloud compute ssh <instance name> to ssh to the instance.
Next, run docker ps to find the container running your application code. You should see a few side-car containers like nginx, but if you look through the names of the containers you should see one for your application.
Finally, you could docker exec -it <container id> -- bash to create a shell on the instance. Or instead of bash, perhaps run a cat command or whatever else you need to do to recover your file.