I am learning how to connect two microservices, first without using a Docker Compose file.
When I include the following IP address
eureka.client.serviceUrl.defaultZone=http://172.17.0.2:8761/eureka in the application.properties file
and run docker run --name vehicle -p 8080:8080 vehicle -- I manage to connect Eureka and Vehicle Microservices.
BUT if I use the name of the Eureka microservice instead of its address in the application.properties file: eureka.client.serviceUrl.defaultZone=http://discovery:8761/eureka
and run docker run --name vehicle -p 8080:8080 vehicle -- it does not work.
ONLY if I override the env variable like this:
docker run --name vehicle -p 8080:8080 -e EUREKA_CLIENT_SERVICEURL_DEFAULTZONE=http://172.17.0.2:8761/eureka
OR if I add a link:
docker run --name vehicle -p 8080:8080 --link discovery:discovery vehicle -- it works fine.
My question is why does it work immediately when I include the IP address into the URL in the application.properties file, but I need to use a link or override the URL address if I specify the service name?
My reasoning is that Docker has an embedded DNS system as shown in the picture, thus it should be able to recognize microservices by both their names and addresses.
Please help me clarify my understanding.
Related
I have one container of springboot application on docker,and one container of postgres with all the settings.How can I run both of them by linking them together.
The image springboot-postgresql corresponds to spring boot application,and postgres refers to postgresql.
Postgres is listening to 0.0.0.0,port 5432.
Please suggest,if there's another way other than making a .yml file and using docker compose up .
Thanks for the help.
The way you can communicate between each container is using docker network,
First, you need to create a network:
$ docker network create sprintapp
Above, the command creates a network named sprintapp
Then, you need to specify to a container to be inside the network:
$ docker run --name [CONTAINERNAME] --network sprintapp [IMAGE]
This way, all containers within the network could talk to each other, using [CONTAINERNAME] as the URI to locate it.
More info about this:
docker run reference
docker network reference
I have recently started exploring the microservice architecture using jhipster and was trying to install and run the jhipster-registry from docker hub. Docker shows that the registry is running, but I am unable to access it on port 8761.
Pulled the image with docker pull jhipster/jhipster-registry
Started the container with docker run --name jhipster-registry -d jhipster/jhipster-registry
Here's a snapshot of what docker container ls returns:
Am I missing something over here?
You are starting the JHipster Registry container, but you aren't exposing the port.
You can expose a port by passing the port flag -p 8761:8761 which will enable you to connect to it via localhost:8761 or 127.0.0.1:8761 in a browser.
You may need to configure some environment variables for the JHipster Registry to start correctly. These may depend on your generated app's options, such as authentication type. For convenience JHipster apps come with a docker-compose.yml file. You can start it with docker-compose -f src/main/docker/jhipster-registry.yml up, as documented.
I'm new with docker and I'm probably missing a lot, although i went through the basic documentation and I'm trying to deploy a simple Spring Boot API
I've deployed my API as a docker-spring-boot .jar file , then i installed docker and pushed it with the following commands:
sudo docker login
sudo docker tag docker-spring-boot phillalexakis/myfirstapi:01
sudo docker push phillalexakis/myfirstapi:01
Then i started the API with the docker run command:
sudo docker run -p 7777:8085 phillalexakis/myfirstapi:01
When i visit localhost:7777/hello I'm getting the desired response
This is my Dockerfile
FROM openjdk:8
ADD target/docker-spring-boot.jar docker-spring-boot.jar
EXPOSE 8085
ENTRYPOINT ["java","-jar","docker-spring-boot.jar"]
Based on this answered post this the command to get the ip address
docker inspect -f '{{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}' container_name_or_id
So, i run it with container_name_or_id = phillalexakis/myfirstapi:01 and I'm getting this error
Template parsing error: template: :1:24: executing "" at <.NetworkSettings.Networks>: map has no entry for key "NetworkSettings"
If i manage somehow to get the IP will i be able to visit it and get the same response?
This is how i have it in my mind: ip:7777/hello
You have used the image name and not the container name.
Get the container name by executing docker ps.
The container ID is the value in the first column, the container name is the value in the last column. You can use both.
Then, when you have the IP, you will be able to access your API at IP:8085/hello, not IP:7777/hello
The port 7777 is available on the Docker Host and maps to the port 8085 on the container. If you are accessing the container directly - which you do, when you use its IP address - you need to use the port that the container exposes.
There is also another alternative:
You can give the container a name when you start it by specifying the --name parameter:
sudo docker run -p 7777:8085 --name spring_api phillalexakis/myfirstapi:01
Now, from your Docker host, you can access your API by using that name: spring_api:8085/hello
You should never need to look up that IP address, and it often isn't useful.
If you're trying to call the service from outside Docker space, you've done the right thing: use the docker run -p option to publish its port to the host, and use the name of the host to access it. If you're trying to call it from another container, create a network, make sure to run both containers with a --net option pointing at that network, and they can reach other using the other's --name as a hostname, and the container-internal port the other service is listening on (-p options have no effect and aren't required).
The Docker-internal IP address just doesn't work in a variety of common situations. If you're on a different host, it will be unreachable. If your local Docker setup uses a virtual machine (Docker Machine, Docker for Mac, minikube, ...) you can't reach the IP address directly from the host. Even if it does work, when you delete and recreate the container, it's likely to change. Looking it up as you note also requires an additional (privileged) operation, which the docker run -p path avoids.
The invocation you have matches the docker inspect documentation (as #DanielHilgarth notes, make sure to run it on the container and not the image). In the specific situation where it will work (you are on the same native-Linux host as the container) you will need to use the unmapped port, e.g. http://172.17.0.2:8085/hello.
Mac here, running Docker Community Edition Version 17.12.0-ce-mac49 (21995).
I have Dockerized a web app with a Dockerfile like so:
FROM openjdk:8
RUN mkdir /opt/myapp
ADD build/libs/myapp.jar /opt/myapp
ADD application.yml /opt/myapp
ADD logback.groovy /opt/myapp
WORKDIR /opt/myapp
EXPOSE 9200
ENTRYPOINT ["java", "-Dspring.config=.", "-jar", "myapp.jar"]
I then build that image like so:
docker build -t myapp .
I then run a container of that image like so:
docker run -it -p 9200:9200 --net="host" --env-file ~/myapp-local.env --name myapp myapp
In the console I see the app start up without any errors, and all seems to be well. Even my metrics publishes (which publish heartbeat and other health metrics every 20 seconds) are printing to the console as I would expect them to. Everything seems to be fine.
Except when I go to run a curl against my app from another terminal/session:
curl -i -H "Content-Type: application/json" -X POST -d '{"username":"heyitsme","password":"12345"}' http://localhost:9200/v1/auth/signIn
curl: (7) Failed to connect to localhost port 9200: Connection refused
Now, if this were a situation where the /v1/auth/signIn path wasn't valid, or if there was something wrong with my request entity/payload, the server would pick up on it and send an error (I assure you; as I can confirm this exact same curl works when I run the server outside of Docker as just a standalone service).
So this is definitely a situation where the curl command can't connect to localhost:9200. Again, when I run my app outside of Docker, that same curl command works perfectly, so I know my app is trying to standup on port 9200.
Any ideas as to what could be going wrong here, or how I could begin troubleshooting?
The way you run your container has 2 conflicting parts:
-p 9200:9200 says: "publish (bind) port 9200 of the container to port 9200 of the host"
--net="host" says: "use the host's networking stack"
According to Docker for Mac - Networking docs / Known limitations, use cases, and workarounds, you should only publish a port:
I want to connect to a container from the Mac
Port forwarding works for localhost; --publish, -p, or -P all work. Ports exposed from Linux are forwarded to the Mac.
Our current recommendation is to publish a port, or to connect from another container. This is what you need to do even on Linux if the container is on an overlay network, not a bridge network, as these are not routed.
The command to run the nginx webserver shown in Getting Started is an example of this.
$ docker run -d -p 80:80 --name webserver nginx
Check that your app bind to 0.0.0.0:9200 and not localhost:9200 or something similar
Problem seems to be in the network mode you are running the container.
Quick test: Login to your container and run the curl cmd there, hopefully it works. That would isolate the problem to request not being forwarded from host to container.
Try running your container on the default bridge network and test.
Refer to this blog for details on the network modes in docker
TLDR; You will need to add an IPtables entry to allow the traffic to enter your container.
I have spring boot application which communicate with ElasticSearch 5.0.0 alpha 2.
My application successfully communicate with elastic and preform several queries.
When I try to dockerize my application, it fails to communicate with ElasticSearch, and I get the following error:
None of the configured nodes are available: [{#transport#-1}{127.0.0.1}{127.0.0.1:9300}]
I have spent a lot of time on the internet, but I have found problems when the ElasticSearch is dockerized, but in my case, the client is dockerized, and it is working fine without the docker.
The command I used to create the docker image is: docker build -t my-service .
The DockerFile is:
FROM java:8
VOLUME /tmp
ADD ./build/libs/myjarfile-2.0.0.jar app.jar
EXPOSE 8090
RUN sh -c 'touch /app.jar'
ENTRYPOINT ["java","-Djava.security.egd=file:/dev/./urandom","-jar","/app.jar"]
To execute the image i use: docker run --name myname -d -p 8090:8090 -t my-service
Can someone share his/her experience with this issue?
Thanks
Guy Hudara
The problem is that your elasticsearch is not available on your dockerized host. When you put something in a docker container it also gets isolated on a network layer and localhost is localhost of the docker container but not the host itself. Therefore if you have elasticsearch also in a docker container use container linking and environment variable injection or reference your host machines address of your main network interface – not loopback – to your app.
Option 1
assuming that elasticsearch exposes 9200 try to run the following
$ docker run -d --name=elasticsearch elasticsearch
$ docker run -d --name=my-app --link elasticsearch:elasticsearch -p 8090:8090 my-app
Then you can define elasticsearch address in your app using env variable ${ELASTICSEARCH_PORT_9200_TCP_ADDR}.
Option 2
assuming your host machine runs on 192.168.1.10 you can also do the following:
$ docker run -d -p 9200:9200 elasticsearch
$ docker run -d -p 8090:8090 my-app
note that the name for the easticsearch container is optional here but the exposing of elasticsearch port mandatory. In this case you'll have to configure your elasticsearch host in your app given address of 192.168.1.10.