I am running the below script and getting error.
#!/bin/bash
webproxy=$(sudo docker ps -a --format "{{.Names}}"|grep webproxy)
webproxycheck="curl -k -s https://localhost:\${nginx_https_port}/HealthCheckService"
if [ -n "$webproxy" ] ; then
sudo docker exec $webproxy sh -c "$webproxycheck"
fi
Here is my docker ps -a output
$sudo docker ps -a --format "{{.Names}}"|grep webproxy
webproxy-dev-01
webproxy-dev2-01
when i run the command individually it works. For Example:
$sudo docker exec webproxy-dev-01 sh -c 'curl -k -s https://localhost:${nginx_https_port}/HealthCheckService'
HEALTHCHECK_OK
$sudo docker exec webproxy-dev2-01 sh -c 'curl -k -s https://localhost:${nginx_https_port}/HealthCheckService'
HEALTHCHECK_OK
Here is the error i get.
$ sh healthcheck.sh
OCI runtime exec failed: exec failed: container_linux.go:348: starting container process caused "exec: \"webproxy-dev-01\": executable file not found in $PATH": unknown
Could someone please help me with the error. Any help will be greatly appreciated.
Because the variable contains two tokens (on two separate lines) that's what the variable expands to. You are running
sudo docker exec webproxy-dev-01 webproxy-dev2-01 ...
which of course is an error.
It's not clear what you actually expect to happen, but if you want to loop over those values, that's
for host in $webproxy; do
sudo docker exec "$host" sh -c "$webproxycheck"
done
which will conveniently loop zero times if the variable is empty.
If you just want one value, maybe add head -n 1 to the pipe, or pass a more specific regular expression to grep so it only matches one container. (If you have control over these containers, probably run them with --name so you can unambiguously identify them.)
Based on your given script, you are trying to "exec" the following
sudo docker exec webproxy-dev2-01
webproxy-dev-01 sh -c "curl -k -s https://localhost:${nginx_https_port}/HealthCheckService"
As you see, here is your error.
sudo docker exec webproxy-dev2-01
webproxy-dev-01 [...]
The problem is this line:
webproxy=$(sudo docker ps -a --format "{{.Names}}"|grep webproxy)
which results in the following (you also posted this):
webproxy-dev2-01
webproxy-dev-01
Now, the issue is, that your docker exec command now takes both images names (coming from the variable assignment $webproxy), interpreting the second entry (which is webproxy-dev-01 and sepetrated by \n) as the exec command. This is now intperreted as the given command which is not valid and cannot been found: That's what the error tells you.
A workaround would be the following:
webproxy=$(sudo docker ps -a --format "{{.Names}}"| grep webproxy | head -n 1)
It only graps the first entry of your output. You can of course adapt this to do this in a loop.
A small snippet:
#!/bin/bash
webproxy=$(sudo docker ps -a --format "{{.Names}}"| grep webproxy )
echo ${webproxy}
webproxycheck="curl -k -s https://localhost:\${nginx_https_port}/HealthCheckService"
while IFS= read -r line; do
if [ -n "$line" ] ; then
echo "sudo docker exec ${line} sh -c \"${webproxycheck}\""
fi
done <<< "$webproxy"
Such a feature is useful when running multiple docker commands in one that follow this pattern:
docker do_smth $(docker query_smth)
For example:
docker stop $(docker ps -q)
or
docker rm $(docker ps -a -q)
or
docker network rm $(docker inspect ... --format ...)
If the inner docker command returns an empty list, the outer command will fail because and will display the help.
"docker stop" requires at least 1 argument.
See 'docker stop --help'.
Usage: docker stop [OPTIONS] CONTAINER [CONTAINER...] [flags]
Stop one or more running containers
Is there a way to silence docker or make docker not complain on empty lists? Something like: "Kill everybody. If there is no one, job done."
This would be similar to mkdir -p exiting_directory vs mkdir exiting_directory where the former will not complain if the directories exist.
For scripting where the result may be empty, I prefer to use xargs --no-run-if-empty:
docker ps -aq | xargs --no-run-if-empty docker rm
I seem to be stuck here. I'm attempting to write a bash function that starts x number of docker containers, wish an array that holds exposed ports for the given app. I don't want to loop over the array, just the commands, while referencing the array to get the value. The function looks like this:
#!/bin/bash
declare -a HOSTS=( ["app1"]="8002"
["app2"]="8003"
["app3"]="8008"
["app4"]="8009"
["app5"]="8004"
["app6"]="8007"
["app7"]="8006" )
start() {
for app in "$#"; do
if [ "docker ps|grep $app" == "$app" ]; then
docker stop "$app"
fi
docker run -it --rm -d --network example_example \
--workdir=/home/docker/app/src/projects/"$app" \
--volume "${PWD}"/example:/home/docker/app/src/example \
--volume "${PWD}"/projects:/home/docker/app/src/projects \
--volume "${PWD}"/docker_etc/example:/etc/example \
--volume "${PWD}"/static:/home/docker/app/src/static \
--name "$app" --hostname "$app" \
--publish "${HOSTS["$app"]}":"${HOSTS["$app"]}" \
example ./manage.py runserver 0.0.0.0:"${HOSTS[$app]}";
echo "$app"
done
}
And I want to pass arguments like so:
./script.sh start app1 app2 app4
Right now it isn't echoing the app so that points towards the for loop being declared incorrectly...could use some pointers on this.
This line:
if [ "docker ps|grep $app" == "$app" ];
doesn't do what you want. It looks like you mean to say:
if [ "$(docker ps | grep "$app")" == "$app" ];
but you could fail to detect two copies of the application running, and you aren't looking for the application as a word (so if you look for rm you might find perform running and think rm was running).
You should consider, therefore, using:
if docker ps | grep -w -q "$app"
then …
fi
This runs the docker command and pipes the result to grep, and reports on the exit status of grep. The -w looks for a word containing the value of "$app", but does so quietly (-q), so grep only reports success (exit status 0) if it found at least one matching line or failure (non-zero exit status) otherwise.
docker ps -f lets you conveniently check programmatically whether a particular image is running.
for app in "$#"; do
if docker ps -q -f name="$app" | grep -q .; then
docker stop "$app"
:
Unfortunately, docker ps does not set its exit code (at least not in the versions I have available -- I think it has been fixed in some development version after 17.06 but I'm not sure) so we have to use an ugly pipe to grep -q . to check whether the command produced any output. The -q flag just minimizes the amount of stuff it prints (it will print just the container ID instead of a bunch of headers and columnar output for each matching container).
I have bash script which stops and remove all docker container by image name.
I can stop and remove all docker container by image name by single command
docker rm $(docker stop $( docker ps -a -q --filter ancestor=image_name))
But if container not exist this expression docker ps -a -q --filter ancestor=image_name not returns nothing and docker stop command fails. How can I remove all containers by image name and do nothing if it already removed?
Try this...
for i in $(docker ps -a -q --filter ancestor=image_name); do docker rm $(docker stop $i); done
It should only call docker rm if docker ps returns results. Works in my environment.
What's the simplest way to get an environment variable from a docker container that has not been declared in the Dockerfile?
For instance, an environment variable that has been set through some docker exec container /bin/bash session?
I can do docker exec container env | grep ENV_VAR, but I would prefer something that just returns the value.
I've tried using docker exec container echo "$ENV_VAR", but the substitution seems to happen outside of the container, so I don't get the env var from the container, but rather the env var from my own computer.
Thanks.
To view all env variables:
docker exec container env
To get one:
docker exec container env | grep VARIABLE | cut -d'=' -f2
The proper way to run echo "$ENV_VAR" inside the container so that the variable substitution happens in the container is:
docker exec <container_id> bash -c 'echo "$ENV_VAR"'
You can use printenv VARIABLE instead of /bin/bash -c 'echo $VARIABLE. It's much simpler and it does not perform substitution:
docker exec container printenv VARIABLE
The downside of using docker exec is that it requires a running container, so docker inspect -f might be handy if you're unsure a container is running.
Example #1. Output a list of space-separated environment variables in the specified container:
docker inspect -f \
'{{range $index, $value := .Config.Env}}{{$value}} {{end}}' container_name
the output will look like this:
ENV_VAR1=value1 ENV_VAR2=value2 ENV_VAR3=value3
Example #2. Output each env var on new line and grep the needed items, for example, the mysql container's settings could be retrieved like this:
docker inspect -f \
'{{range $index, $value := .Config.Env}}{{println $value}}{{end}}' \
container_name | grep MYSQL_
will output:
MYSQL_PASSWORD=secret
MYSQL_ROOT_PASSWORD=supersecret
MYSQL_USER=demo
MYSQL_DATABASE=demodb
MYSQL_MAJOR=5.5
MYSQL_VERSION=5.5.52
Example #3. Let's modify the example above to get a bash friendly output which can be directly used in your scripts:
docker inspect -f \
'{{range $index, $value := .Config.Env}}export {{$value}}{{println}}{{end}}' \
container_name | grep MYSQL
will output:
export MYSQL_PASSWORD=secret
export MYSQL_ROOT_PASSWORD=supersecret
export MYSQL_USER=demo
export MYSQL_DATABASE=demodb
export MYSQL_MAJOR=5.5
export MYSQL_VERSION=5.5.52
If you want to dive deeper, then go to Go’s text/template package documentation with all the details of the format.
Since we are dealing with JSON and unlike the accepted answer, we don't need to exec the container.
docker inspect <NAME|ID> | jq '.[] | .Config.Env'
Output sample
[
"PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin",
"NGINX_VERSION=1.19.4",
"NJS_VERSION=0.4.4",
"PKG_RELEASE=1~buster"
]
To retrieve a specific variable
docker inspect <NAME|ID> | jq -r '.[].Config.Env[]|select(match("^<VAR_NAME>"))|.[index("=")+1:]'
See jq
None of the above answers show you how to extract a variable from a non-running container (if you use the echo approach with run, you won't get any output).
Simply run with printenv, like so:
docker run --rm <container> printenv <MY_VAR>
(Note that docker-compose instead of docker works too)
If by any chance you use VSCode and has installed the docker extension, just right+click on the docker you want to check (within the docker extension), click on Inspect, and there search for env, you will find all your env variables values
We can modify entrypoint of a non-running container with the docker run command.
Example show PATH environment variable:
using bash and echo: This answer claims that echo will not produce any output, which is incorrect.
docker run --rm --entrypoint bash <container> -c 'echo "$PATH"'
using printenv
docker run --rm --entrypoint printenv <container> PATH
#aisbaa's answer works if you don't care when the environment variable was declared. If you want the environment variable, even if it has been declared inside of an exec /bin/bash session, use something like:
IFS="=" read -a out <<< $(docker exec container /bin/bash -c "env | grep ENV_VAR" 2>&1)
It's not very pretty, but it gets the job done.
To then get the value, use:
echo ${out[1]}
This command inspects docker stack processes' environment in the host :
pidof dockerd containerd containerd-shim | tr ' ' '\n' \
| xargs -L1 -I{} -- sudo xargs -a '/proc/{}/environ' -L1 -0
The first way we use to find the ENV variables is docker inspect <container name>
The second way is docker exec <4 alphanumeric letter of CONTAINER id> bash -c 'echo "$ENV_VAR"'
There is a misconception in the question, that causes confusion:
you cannot access a "running session", so no bash session can change anything.
docker exec -ti container /bin/bash
starts a new console process in the container, so if you do export VAR=VALUE this will go away as soon as you leave the shell, and it won't exist anymore.
Perhaps a good example:
# assuming TESTVAR did not existed previously this is empty
docker exec container env | grep TESTVAR
# -> TESTVAR=a new value!
docker exec container /bin/bash -c 'TESTVAR="a new value!" env' | grep TESTVAR
# again empty
docker exec container env | grep TESTVAR
The variables from env come from the Dockerfile or command, docker itself and whatever the entrypoint sets.
The other answers here are good. But if you really need to get the environmental properties used when starting a program, then you can inspect the /proc/pid/environ contents in the container, where pid is the container process id of the running comand.
# environmental props
docker exec container cat /proc/pid/environ | tr '\0' '\n'
# you can check this is the correct pid by checking the ran command
docker exec container cat /proc/pid/cmdline | tr '\0' ' '