CODEWITHSUNDEEP
dockerdockerfile
Tushar Gandhi
Tushar Gandhi

Reputation: 247

DNS resolution with the container

I have a docker image which is build from the following file.

FROM java:7
MAINTAINER Tushar Gandhi

ARG version
ENV version=$version
ARG port
ENV port=$port

RUN mkdir -p /cacheDir/services/live/prediction/p$port/$version/logs
RUN ls -tlr /cacheDir/services/live/prediction/p$port/

RUN mkdir -p /cacheDir/services/releases/prediction/p$port/$version/

RUN mkdir -p /cacheDir/services/predictionmodel
ADD target/predictionDependencies/* /cacheDir/services/predictionmodel/

ADD /target/prediction-0.0.13-SNAPSHOT.jar /cacheDir/services/releases/prediction/p$port/$version/prediction-0.0.13-SNAPSHOT.jar

ADD /target/instance.properties /cacheDir/services/releases/prediction/p$port/$version/instance.properties

ADD /target/logback.xml /cacheDir/services/releases/prediction/p$port/$version/logback.xml

RUN ls -ltr /cacheDir/services/live/prediction/p$port/$version/
RUN ls -ltr /cacheDir/services/releases/prediction/p$port/$version/
RUN ls -ltr /cacheDir/services/predictionmodel

ENTRYPOINT ["sh","-c","java -server -Xmx2g -Xloggc:/cacheDir/services/live/prediction/p${port}/${version}/logs/gc.log -verbose:gc -XX:+PrintGCDateStamps -XX:+PrintGCDetails -XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=/cacheDir/services/live/prediction/p${port}/${version}/oom.dump -Dlogback.configurationFile=/cacheDir/services/releases/prediction/p${port}/${version}/logback.xml -Dlog.home=/cacheDir/services/live/prediction/p${port}/${version}/logs -Dlogback.debug=true -Dbroker.l^Ct=sv-kafka6.pv.sv.nextag.com:9092,sv-kafka7.pv.sv.nextag.com:9092,sv-kafka8.pv.sv.nextag.com:9092,sv-kafka9.pv.sv.nextag.com:9092 -jar /cacheDir/services/releases/prediction/p${port}/${version}/prediction-0.0.13-SNAPSHOT.jar $port /cacheDir/services/releases/prediction/p${port}/${version}/instance.properties /com/abc/services/$ZK_PATH"]

I'm using the following build command to build the image.

docker build --build-arg version=test1 --build-arg port=3001 -f Dockerfile -t prediction:test1 .

The image creation is successful and the container comes up to be successful. Run command used

sudo docker run -p 7105:3001 -v ~/PredictionVolume/logs/:/cacheDir/services/live/prediction/p5030/Testing1/logs/ -e ZK_PATH=qa -t prediction:test

Now, the problem lies in that my application when runs in a docker container, it tries to access URL qa-zk1.com:2181. This URL is accessible from my system but not from the docker container. Can anyone please suggest a way to make the URL accessible from the container.

[Edit] I have been trying different methods and came across that I was able to ping google.com. This showed me that internet is working. If internet is working, then that URL should also be accessible, but it isn't, therefore it seems to be a problem of DNS resolution. I tried with the IP address and was able to hit the service properly, now I need to find out how to enable that search pattern using a URL rather than an IP address.

Upvotes: 2

Views: 418

Answers (1)

evgenyl
evgenyl

Reputation: 8117

In case you can reach the site by IP, it means that inside the container you are pointing to the DNS server, which does not know "qa-zk1.com" name.

You can 2 options:

  1. Add your ip to the local hosts file

/etc/hosts

  1. Update container's DNS configuration

See Configure container DNS for more details

Upvotes: 2

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