I am facing an issue running a docker image based on alpine linux that runs a java process (GoCD server). The java process itself tries to run some code to clone a git repository locally however I am getting a Couldn't resolve host exception. I tried to manually clone the git repo from within the container using 'git clone' and had no issue.
In addition, I am able to ping the domain from within the docker container by running ping my-service-url.com with no issues and also from the host machine with the same result. It seems java has some difficulties resolving the name but I am not sure how to fix it.
I tried creating a new image with RUN echo 'hosts: files mdns4_minimal [NOTFOUND=return] dns mdns4' >> /etc/nsswitch.conf. I read in another question that would fix it but no luck. The whole Dockerfile looks like the following:
FROM gocd/gocd-server:v17.5.0
RUN echo 'hosts: files mdns4_minimal [NOTFOUND=return] dns mdns4' >> /etc/nsswitch.conf
ADD json-config-plugin-0.2.jar /godata/plugins/external/json-config-plugin-0.2.jar
ENTRYPOINT ["/docker-entrypoint.sh"]
I am running on AWS ECS, ipv4 forwarding is set to 1 and network mode is bridge. I am running out of ideas.
Related
I'm trying to install/run jenkins manually without pulling the Jenkins image from the docker-hub
for this exercise I have used the ubuntu image container and I did the following:
Install jdk-11 on the container
Set up the JAVA_HOME env variable
Install jenkins with apt-get
Run jenkins with the command service jenkins start
then status output is the following
root#42024442b87b:/# service jenkins status
Correct java version found
Jenkins Automation Server is running with the pid 89
Now I don't now how to access the jenkins server running in the container from my host.
thanks in advance
Docker containers are not reachable using the network from the host system by default. You need to expose a container's host, meaning that the port will be opened on the host machine and all traffic forwarded to the container.
Running docker with -p 8080:8080 forwards 8080. Take a look at the syntax here.
You can also specify which port on the host machine is supposed to be mapped to a container's port with something like -p 1234:8080.
You can also use the EXPOSE keyword in your Dockerfile.
I m using docker toolbox in Windows 7, and when I run a command like
'docker run -p 5000:5000 -d in28min/todo-rest-api-h2:1.0.0.RELEASE'
, it worked and app executed.
-- Here is shown that app started.
Besides 'docker container ls' command give me running port.
So, when I request to corresponding URL(http://localhost:5000/hello-world), it does not respond (This site can’t be reached). What can be a problem here? As far as I know, that '-p' command allows us to request. Thanks in advance
I found solution. It is because of 'docker-machine ip'. which is different in docker toolbox. Default docker-machine ip is 192.168.99.100, not localhost.
I have some tests that i am running using docker-compose. The problem is that the docker logs are saved within the container (which makes debugging complicated).
I am looking for a way to configure docker-compose to save all logs on the machine where i am running the tests, instead of the container. Preferably some configuration of docker-compose.yml file, but i am open to any suggestion
It is not docker-compose, who saves your logs and has to be reconfigured. It is docker itself or your service, running inside that docker, depending on what logs do you mean.
If you are talking about docker logs, you should refer to docker log driver configuration page:
https://docs.docker.com/config/containers/logging/configure/
If you are talking about logs, produced by your services, just mount writable volume from your host pc into container, and configure your software to log into that folder.
You can achieve this like the following code does:
docker-compose.yml:
...
my-service:
image: xxx
entrypoint: ["sh", "-c", "echo 'Hello World!' > /path/inside/docker/some_log_file" ]
volumes:
- /path/on/host:/path/inside/docker
...
you service now should just log into /path/inside/docker/some_log_file.
On host machine you will see all these files in /path/on/host
I guess the scenario you are looking is you have docker containers scattered accross multiple host machines. so probably you need to make the docker container to the host machine volume and see if you can map the host volume to a share file system.
or write some scripts that are running on the docker host machines to copy the log files from a mapped docker volume on the docker host to a remote location of your choice using scp command etc.
or use some log aggregation frame works https://stackify.com/log-aggregation-101/
I am experimenting with Docker for the first time, and am trying to get a Spring Boot web app to run inside a Docker container. I am building the app (which packages up into a self-contained jar) and then adding it to the Docker image (which is what I want).
You can find my SSCCE at this Bootup repo on GitHub, whose README has all the instructions to reproduce what I'm seeing. But basically:
I build the web app into a jar
Run docker build -t bootup . which succeeds
Run docker run -it -p 9200:9200 -d --name bootup bootup and then container seems to start up just fine, as is evidence by the docker ps output below
However, when I point a browser to http://localhost:9200, I get nothing
docker ps output:
CONTAINER ID IMAGE COMMAND CREATED
a8c4ee64a1bc bootup "/bin/sh -c 'java -ja" 2 days ago
STATUS PORTS NAMES
Up 12 seconds 0.0.0.0:9200->9200/tcp bootup
The web app is configured to run on port 9200, not the Java default of 8080. You can see this for yourself by running the app outside of docker (so, just locally on you host machine) by running ./gradlew clean build && java -jar build/libs/bootup.jar.
To my knowledge, there is no Firewall running on my host that would be blocking ports (I am on Mac 10.11.5 and verified that System Preferences >> Security & Privacy >> Firewall is turned off).
Can anyone spot where I'm going awry?
Updates:
I ran a curl, netstat and lsof on the host:
HOST:
curl http://localhost:9200
curl: (52) Empty reply from server
netstat -an | grep 9200
tcp6 0 0 ::1.9200 *.* LISTEN
tcp4 0 0 *.9200 *.* LISTEN
lsof -n -i4TCP:9200 | grep LISTEN
com.docke 2578 myuser 19u IPv4 <someHexNumber> 0t0 TCP *:wap-wsp (LISTEN)
And then docker exec'd into the container and ran another netstat:
CONTAINER:
netstat -an | grep 9200
bash: netstat: command not found
Update w/ photos:
Picture of my browser (Chrome) pointed to http://localhost:9200:
Picture of the source code at http://localhost:9200:
Picture of Chrome Developer Tools inspecting the page at http://localhost:9200:
Picture of the Network tab in Chrome Developer Tools:
What the heck is going on here?!?!? According to the source, the browser should be rendering my Well hello there, from Dockerland! message just fine. According to the actual browser page, it looks like there is a networking error. And according to Chrome Developer Tools, my app is returning all sorts of HTML/CSS/JS content that is not even remotely apart of my app (check out the source code, see for yourself)!!!
The Dockerfile doesn't expose 9200 to the daemon. Add
EXPOSE 9200
to the Dockerfile before ENTRYPOINT
Assuming you are using Docker Toolbox and not the beta ...
There is a 3 step process for exposing a port properly:
use EXPOSE 8080 where 8080 is just a port number in the Dockerfile
use -p 8080:8080 in your docker run command
Make sure that you setup port forwarding in Oracle Virtual Box so that the boot2docker machine is able to receive requests from port 8080.
This applies to both Windows and OSX where Docker Toolbox is being used. Linux doesn't use Oracle VirtualBox to run docker so those hosts do not need to do the third point
I ran your repo as-is on Docker 1.12 on OSX.
If you look carefully at your container startup:
2016-08-29 20:52:31.028 INFO 5 --- [ main] o.eclipse.jetty.server.ServerConnector : Started ServerConnector#47949d1a{HTTP/1.1}{0.0.0.0:8080}
2016-08-29 20:52:31.033 INFO 5 --- [ main] .s.b.c.e.j.JettyEmbeddedServletContainer : Jetty started on port(s) 8080 (http/1.1)
Although application.yml and Dockerfile both contain 9200, the application is starting on 8080
Going to add another answer here because I saw something related to the Github Repo that you posted:
So the repo is a spring boot repo with an application.yml file.
Your Dockerfile looks like this:
FROM openjdk:8
RUN mkdir /opt/bootup
ADD build/libs/bootup.jar /opt/bootup
WORKDIR /opt/bootup
EXPOSE 9200
ENTRYPOINT java -jar bootup.jar
Which is adding the built jar to the image. If my understanding is correct, the jar does not include application.yml because:
It is not part of the build (gradle would package the src/main only). It is sitting on the project root folder
It is not explicitly added to Docker
So therefore one can assume that your app is actually running on 8080 (the default) at the moment?
A couple of options that one could try:
Try exposing 8080 instead of 9200 (or expose both) and see if that makes a difference?
The entrypoint command can append the port --server.port=9200
The application.yml file should be added to the image (you might need to add an argument to reference it properly) [ADD application.yml /opt/bootup, after first ADD command]
Include the application.yml file in src/main/resources so that spring boot can pick it up automatically.
References
Spring Boot reference documentation on the order of loading for external configuration
Good News! (for MacOSx 10.15.7)
I found the same issue as you, and I was able to solve it by directly opening VirutalBox connection
Go here first:
changed to bridged then logged into the virtual machine within VirtualBox
And found the actual machine's adapter labeled:
eth0
after I noted the setting it was originally NAT so I changed to bridged and then
I was able to use its address vs. localhost.
After I used the public address I used:
curl -i [bridged_ip_address_here]:9200
it then worked flawlessly.
However I also noticed some firewalls and accessibility options that needed permission as well.
I pray this helps you.
Spring boot demo app tried on localhost and successfully run the application. I even installed
gradle,jdk and other dependencies
easily on aws instance . Even though i ran ./gradlew bootRun of sample application successfully .
Like http:// localhost:8080 aws instane isn't working according to my path like http://myip:8080.
Let me know what exactly i am doing wrong with this and also to make sure i added custom tcp rule such as 8080 .
Besides adding custom tcp rule 8080, try to add the following rule into your security group.
Type: Custom ICMP Rule
Protocol: Echo Request
Port Range: N/A
Source: 0.0.0.0/0
And then try to ping YourIP in order to see if your EC2 machine can be reach from internet. If your EC2 ip is pingable, then I guess the reason why you cannot access http://myip:8080 is your spring boot failed to start in EC2.
You can ssh into your ec2 and investigate your jar. I don't know any clever method but my method is:
After ssh into the ec2 machine,
Find your jar name by ps -A -F . In my case I can find java -jar application.jar
Find your jar path by sudo find / -name application.jar . In my case I can find /var/app/current/application.jar
Then you can cd /var/app/current/ and java -jar application.jar . If you are lucky, you can find some hints from the spring boot log.
In order for this call to work there are a couple of prerequisites.I will try to make a short list, other things could arise depending on the environment.
Make sure the public IP address is the same as the one you know. This changes after each reboot. If you do not want this behavior you can use an elastic IP
The 8080 port is accessible from the Internet. Here are some steps to make sure this is the case: http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/authorizing-access-to-an-instance.html