I'm trying to run apache in a container and I need to set the tomcat server in a variable since tomcat container runs in a different namespace.
I've set the variable like this but it doesn't work. I've ensured that the variable is present by echoing it in the container and I can ping the host. Documentation says that we can set environment.
I'm not sure why it isn't working...
/etc/httpd/conf.d/workers.properties
worker.ajp13.port=8009
worker.ajp13.host="${TOMCAT_SERVER}"
worker.ajp13.type=ajp13
worker.ajp13.reply_timeout=15000
Figured it out. Had to use parentheses instead of curly braces. Found a example from this site.
worker.ajp12.host=$(TOMCAT_SERVER)
worker.ajp13.type=ajp13
worker.ajp13.reply_timeout=15000
Now I can pass the variable to docker run command like this..
docker run -e TOMCAT_SERVER=tomcat001 --name httpd -p 80:80 -d httpd:0.0.12
As the title says, whats the difference between running a command for a docker-machine as
eval $(docker-machine env mycontainer)
docker run httpd
And
docker $(docker-machine config mycontainer) run httpd
as both create an httpd image under the "mycontainer" ip, but with the second, there's no container shown with "docker ps"
In the first form, you are first evaluating a series of env vars (DOCKER_HOST, DOCKER_CERT_PATH, DOCKER_TLS_VERIFY, DOCKER_MACHINE_NAME) which are configuring your current shell so that any docker command you later launch will talk to the same docker daemon.
In the second form, you are passing the params (--tlsverify, --tlscacert, --tlscert, --tlskey, -H) directly to the docker command. Those will eventually override the values already in your env or the defaults (i.e. connect to local daemon).
In this latest case if you want to see the container you just launched making sure your are talking to the correct server, you have to use the same command line parameters again with docker $(docker-machine config mycontainer) ps
To summarize:
config is more suited for single on-spot commands
env is more convenient for a full session on the same server.
I have a docker container with a environment variable that I want to change on restart time. I have read about the -e option that can be used for that in docker run command (described for instance here).
I have tried to use it with restart:
sudo docker restart 1db2df40d98c -e FOOBAR_VERSION='v1'
However, I get this error:
unknown shorthand flag: 'e' in -e
See 'docker restart --help'.
I have also read about re-building the container with the new environment variable value. However, I'd like to avoid so overhelming alterantive. I just want to restart the container, but with a different environment variable value at starting time.
Any hint/reference/help regarding this problem is really welcome, please.
EDIT: I have also tried doing the restart in two steps, I mean:
sudo docker stop 1db2df40d98c
sudo docker start 1db2df40d98c -e FOOBAR_VERSION='v1'
But the result is the same.
While working behind the corporate proxies..
Why can't docker export the proxy specific value from environment variables
(http_proxy, https_proxy,...).
Usually you get timeout issue while pulling the image, even if the proxy url is mentioned in environment vairable.
I have to set the value (hard-code the same value again) in or by creating the config files in /etc/systemd/system/docker.service.d folder.
If we change the proxy url, we have to make changes in different place. Or is there any way to refer the value from environment variable ?
I have tried the docker run -e env_proxy_variable=proxy_url but got the same timeout issue.
Consider using the below instead:
export HTTP_PROXY=http://xxx:port/
export HTTPS_PROXY=http://xxx:port/
export FTP_PROXY=http://xxx:port/
You can hardcode these variables in the /etc/default/docker file so that they are exported whenever docker is started.
You can check if the environment variable has been exported by typing $(name_of_var). For eg, after running
docker run --env HTTP_PROXY="123.45.21.32" -it ubuntu_latest /bin/bash
type
echo $HTTP_PROXY
It is likely that your DNS server isn't configured. Try
cat /etc/resolv.conf
if you see something like:
nameserver:8.8.8.8
then it's likely that the DNS server is inaccessible behind firewalls. You can pass dns server address along with docker run command like so:
docker run --env HTTP_PROXY="123.45.21.32" --dns=172.10.18.0 -it ubuntu_latest /bin/bash
If I have a docker container that I started a while back, what is the best way to set an environment variable in that running container? I set an environment variable initially when I ran the run command.
$ docker run --name my-wordpress -e VIRTUAL_HOST=domain.example --link my-mysql:mysql -d spencercooley/wordpress
but now that it has been running for a while I want to add another VIRTUAL_HOST to the environment variable. I do not want to delete the container and then just re-run it with the environment variable that I want because then I would have to migrate the old volumes to the new container, it has theme files and uploads in it that I don't want to lose.
I would just like to change the value of VIRTUAL_HOST environment variable.
There are generaly two options, because docker doesn't support this feature now:
Create your own script, which will act like runner for your command. For example:
#!/bin/bash
export VAR1=VAL1
export VAR2=VAL2
your_cmd
Run your command following way:
docker exec -i CONTAINER_ID /bin/bash -c "export VAR1=VAL1 && export VAR2=VAL2 && your_cmd"
Docker doesn't offer this feature.
There is an issue: "How to set an enviroment variable on an existing container? #8838"
Also from "Allow docker start to take environment variables #7561":
Right now Docker can't change the configuration of the container once it's created, and generally this is OK because it's trivial to create a new container.
For a somewhat narrow use case, docker issue 8838 mentions this sort-of-hack:
You just stop docker daemon and change container config in /var/lib/docker/containers/[container-id]/config.json (sic)
This solution updates the environment variables without the need to delete and re-run the container, having to migrate volumes and remembering parameters to run.
However, this requires a restart of the docker daemon. And, until issue issue 2658 is addressed, this includes a restart of all containers.
To:
set up many env. vars in one step,
prevent exposing them in 'sh' history, like with '-e' option (passing credentials/api tokens!),
you can use
--env-file key_value_file.txt
option:
docker run --env-file key_value_file.txt $INSTANCE_ID
Here's how you can modify a running container to update its environment variables. This assumes you're running on Linux. I tested it with Docker 19.03.8
Live Restore
First, ensure that your Docker daemon is set to leave containers running when it's shut down. Edit your /etc/docker/daemon.json, and add "live-restore": true as a top-level key.
sudo vim /etc/docker/daemon.json
My file looks like this:
{
"default-runtime": "nvidia",
"runtimes": {
"nvidia": {
"path": "nvidia-container-runtime",
"runtimeArgs": []
}
},
"live-restore": true
}
Taken from here.
Get the Container ID
Save the ID of the container you want to edit for easier access to the files.
export CONTAINER_ID=`docker inspect --format="{{.Id}}" <YOUR CONTAINER NAME>`
Edit Container Configuration
Edit the configuration file, go to the "Env" section, and add your key.
sudo vim /var/lib/docker/containers/$CONTAINER_ID/config.v2.json
My file looks like this:
...,"Env":["TEST=1",...
Stop and Start Docker
I found that restarting Docker didn't work, I had to stop and then start Docker with two separate commands.
sudo systemctl stop docker
sudo systemctl start docker
Because of live-restore, your containers should stay up.
Verify That It Worked
docker exec <YOUR CONTAINER NAME> bash -c 'echo $TEST'
Single quotes are important here.
You can also verify that the uptime of your container hasn't changed:
docker ps
You wrote that you do not want to migrate the old volumes. So I assume either the Dockerfile that you used to build the spencercooley/wordpress image has VOLUMEs defined or you specified them on command line with the -v switch.
You could simply start a new container which imports the volumes from the old one with the --volumes-from switch like:
$ docker run --name my-new-wordpress --volumes-from my-wordpress -e VIRTUAL_HOST=domain.com --link my-mysql:mysql -d spencercooley/wordpres
So you will have a fresh container but you do not loose the old data. You do not even need to touch or migrate it.
A well-done container is always stateless. That means its process is supposed to add or modify only files on defined volumes. That can be verified with a simple docker diff <containerId> after the container ran a while.
In that case it is not dangerous when you re-create the container with the same parameters (in your case slightly modified ones). Assuming you create it from exactly the same image from which the old one was created and you re-use the same volumes with the above mentioned switch.
After the new container has started successfully and you verified that everything runs correctly you can delete the old wordpress container. The old volumes are then referred from the new container and will not be deleted.
If you are running the container as a service using docker swarm, you can do:
docker service update --env-add <you environment variable> <service_name>
Also remove using --env-rm
To make sure it's addedd as you wanted, just run:
docker exec -it <container id> env
1. Enter your running container:
sudo docker exec -it <container_name> /bin/bash
2. Run command to all available to user accessing the container and copy them to user running session that needs to run the commands:
printenv | grep -v "no_proxy" >> /etc/environment
3. Stop and Start the container
sudo docker stop <container_name>
sudo docker start <container_name>
Firstly you can set env inside the container the same way as you do on a linux box.
Secondly, you can do it by modifying the config file of your docker container (/var/lib/docker/containers/xxxx/config.v2.json). Note you need restart docker service to take affect. This way you can change some other things like port mapping etc.
here is how to update a docker container config permanently
stop container: docker stop <container name>
edit container config: docker run -it -v /var/lib/docker:/var/lib/docker alpine vi $(docker inspect --format='/var/lib/docker/containers/{{.Id}}/config.v2.json' <container name>)
restart docker
I solve this problem with docker commit after some modifications in the base container, we only need to tag the new image and start that one
docs.docker.com/engine/reference/commandline/commit
docker commit [container-id] [tag]
docker commit b0e71de98cb9 stack-overflow:0.0.1
then you can pass environment vars or file
docker run --env AWS_ACCESS_KEY_ID --env AWS_SECRET_ACCESS_KEY --env AWS_SESSION_TOKEN --env-file env.local -p 8093:8093 stack-overflow:0.0.1
the quick working hack would be:
get into the running container.
docker exec -it <container_name> bash
set env variable,
install vim if not installed in the container
apt-get install vim
vi ~/.profile at the end of the file add export MAPPING_FILENAME=p_07302021
source ~/.profile
check whether it has been set! echo $MAPPING_FILENAME(make sure you should come out of the container.)
Now, you can run whatever you're running outside of the container from inside the container.
Note, in case you're worried that you might lose your work if the current session you logged in gets logged off. you can always use screen even before starting step 1. That way if you logged off by chance of your inside running container session, you can log back in.
After understand that docker run an image constructed with a dockerfile , and the only way to change it is build another image stop everything and run everything again .
So the easy way to "set an environment variable in a running docker container" is read dockerfile [1] (with docker inspect) understand how docker starts [1].
In the example [1] we can see that docker start with /usr/local/bin/docker-php-entrypoint and we could edit it with vi and add one line with export myvar=myvalue since /usr/local/bin/docker-php-entrypoint Posix script .
If you can change dockerfile, you can add a call to a script [2] for example /usr/local/bin/mystart.sh and in that file we can set your environment var.
Of course after change the scripts you need restart the container [3]
[1]
$ docker inspect 011aa33ba92b
[{
. . .
"ContainerConfig": {
"Cmd": [
"php-fpm"
],
"WorkingDir": "/app",
"Entrypoint": [
"docker-php-entrypoint"
],
. . .
}]
[2]
/usr/local/bin/mystart.sh
#!/bin/bash
export VAR1=VAL1
export VAR2=VAL2
your_cmd
[3]
docker restart dev-php (container name)
Hack with editing docker inner configs and then restarting docker daemon was unsuitable for my case.
There is a way to recreate container with new environment settings and use it for some time.
1. Create new image from runnning container:
docker commit my-service
a1b2c3d4e5f6032165497
Docker created new image, and answered with its id. Note, the image doesn't include mounts and networks.
2. Stop and rename original container:
docker stop my-service
docker rename my-service my-service-original
3. Create and start new container with modified environment:
docker run \
-it --rm \
--name my-service \
--network=required-network \
--mount type=bind,source=/host/path,target=/inside/path,readonly \
--env 'MY_NEW_ENV_VAR=blablabla OLD_ENV=zzz' \
a1b2c3d4e5f6032165497
Here, I did the following:
created new temporary container from image built on step 1, that will show its output on terminal, will exit on Ctrl+C, and will be deleted after that
configured its mounts and networks
added my custom environment configuration
4. After you worked with temporary container, press Ctrl+C to stop and remove it, and then return old container back:
docker rename my-service-original my-service
docker start my-service
How to set environment variable in a running docker container as a development environment
Basically you can do like in normal linux, adding export MY_VAR="value" to ~/.bashrc file.
Instructions
Using VScode attach to your running container
Then with VScode open the ~/.bashrc file
Export your variable by adding the code in the end of the file
export MY_VAR="value"
Finally execute .bashrc using source command
source ~/.bashrc
You could set an environment variable to a running Docker container by
docker exec -it -e "your environment Key"="your new value" <container> /bin/bash
Verify it using below command
printenv
This will update your key with the new value provided.
Note: This will get reverted back to old on if docker gets restarted.
Use export VAR=Value
Then type printenv in terminal to validate it is set correctly.