I have a container running nifi (--name nifi) exposing port 8080 and another container running nifi registry (--name nifireg) exposing port 10808. I can get to both UI's, and I am able to connect nifi to the registry in the registry services by using the registry container's IP (172.17.0.5). These containers are also on a docker network called nifi-net. My issue is that the registry client is unable to talk to the registry when using the container name.
From the nifi I can ping by container IP as well as by name (ping nifireg), so there is some level of connectivity. But if I change the registry client to point to http://nifireg:180880 or even http://nifi-net.nifireg:18080 it clocks for a while and then eventually returns this error:
Unable to obtain listing of buckets: java.net.ConnectException: Connection refused (Connection refused)
What needs to be done to allow nifi to connect to the nifi registry using the container name?
EDIT: Here is how I set everything up:
docker run -d --name nifi -p 8080:8080 apache/nifi
docker run -d --name nifireg -p 18080:18080 apache/nifi-registry
I added the netorking after the fact, but that shouldn't be an issue.
docker network create nifi-net
docker network connect nifi-net nifi
docker network connect nifi-net nifireg
I don't understand why this solved the problem, but destroying the containers and recreating them with the --net nifi-net option at spin-up solved the problem.
docker run -d --name nifi --net nifi-net -p 8080:8080 apache/nifi
docker run -d --name nifireg --net nifi-net -p 18080:18080 apache/nifi-registry
The docs state that you can add them to a network after the fact, and I am able to ping from one container to the other using the name. I guess it's just a lesson that I need to use docker networking more.
I would suggest using docker-compose to manage the deployment since you can define the network once in docker-compose.yaml and not have to worry about it agian.
Plus it lets you learn about docker networking :P
So I'm trying to setup a new container that needs to communicate with mysql. I setup the mysql container. I did a
docker network ls
to see the name of the network it uses. When I start the snipe-it container using
docker run -d -p 8082:80 -p 443:443 --name="snipeit" --network=mysql_default --mount source=snipe-vol,dst=/var/lib/snipeit --env-file=./snipe-it-env snipe/snipe-it
When going to the web portal of the docker container I get a message from the setup script saying it can't connect to the db. To update the settings in the .env file.
As far as I can tell, the environment variables were all correct.
Use busybox image to diagnose it first:
docker run --rm -it --network=mysql_default busybox
Then in console try to ping your mysql instance: ping mysql or whatever your container name with mysql is defined as a service.
You may check what services are actually running on given network with:
docker network inspect mysql_default
There should be section named "Containers" with proper name of container with mysql - providing it is running right now.
I am trying to make a portable solution to having my application container connect to a postgres container. By 'portable' I mean that I can give the user two docker run commands, one for each container, and they will always work together.
I have a postgres docker container running on my local PC, and I run it like this,
docker run -p 5432:5432 -v $(pwd)/datadir:/var/lib/postgresql/data -e POSTGRES_PASSWORD=qwerty -d postgres:11
and I am able to access it from a python flask app, using the address 127.0.0.1:5432.
I put the python app in a docker container as well, and I am having trouble connecting to the postgres container.
Address 127.0.0.1:5432 does not work.
Address 172.17.0.2:5432 DOES work (172.17.0.2 is the address of the docker container running postgres). However I consider this not portable because I can't guarantee what the postgres container IP will be.
I am aware of the --add-host flag, but it is also asking for the host-ip, which I want to be the localhost (127.0.0.1). Despite several hits on --add-host I wasn't able to get that to work so that the final docker run commands can be the same on any computer they are run on.
I also tried this: docker container port accessed from another container
My situation is that the postgres and myApp will be containers running on the same computer. I would prefer a non-Docker compose solution.
The comment from Truong had me try that approach (again) and I got it working. Here are my steps in case it helps out another. The crux of the problem was needing one container to address another container in a way that was static (didn't change). Using user defined network was the answer, because you can name a container, and thus reference that container IP by that name.
My steps,
docker network create mynet
docker run --net mynet --name mydb -v $(pwd)/datadir:/var/lib/postgresql/data -e POSTGRES_PASSWORD=qwerty -d postgres:11
Now the IP address of the postgres database is mydb, and all the ports of this container are exposed to any other container running in this network.
Now add the front end app,
docker run --net mynet -ti -p 80:80 -v mydockerhubaccount/myapp
I am trying to run a small test server with MS SQL Server running on a Mac in a Linux docker container. Maybe I have the terminology wrong so please correct me if necessary:
host - the macOS desktop with docker installed (ip 10.0.1.73)
container - the Linux instance running in the docker container with SQL Server running in it
remote desktop - another computer on the local area network trying to connect to SQL Server
I followed the MS installation instructions and everything seems to be running fine, except I can't connect to SQL Server from the Remote Desktop
I can connect to the docker host(10.0.1.73) and can ping the IP address
I can connect to SQL Server from the docker host and see the databases etc.
I used the following command to create the docker container
sudo docker run -e "ACCEPT_EULA=Y" -e "SA_PASSWORD=<XXXXXX>" -p 1433:1433 --name sqlserver1 -d microsoft/mssql-server-linux:2017-latest
Thinking that the -p 1433:1433 would map the linux port to the macOS host port and allow the remote computer to access the docker container when connecting to that port on the macOS host from the local area network
This is not working and I assume this may be to do with the network routing on the macOS host
Most solutions I have seen seem to indicate that one should use the VirtualBox UI to modify the network settings - but I don't have that installed
The others seem to have pages and pages of command line instructions that are required
Is there an easy solution somewhere I have missed?
EDIT:
Some more research and I found this explanation about how by default the Docker networking is set up for single host networking. Good explanation for anyone else struggling with the Docker concepts.
It is also worth reading up about the differences between docker containers and virtual machines...
https://youtu.be/Js_140tDlVI
Still trying to find some explanation on multi host networking.
try disabeling the firewall on the host you want to connect to.
port 1433 will be forwarded to the docker container, but your host (MAC) should have port 1433 open to be able to connect to your host.
Using NAT:
Assign the target address to your host interface:
sudo ifconfig en1 alias 10.0.1.74/21 up
Create the docker container and map the port to the second IP address assigned to the host interface
sudo docker run -e "ACCEPT_EULA=Y" -e "SA_PASSWORD=<XXXXXXXXX>" -p 10.0.1.74:1433:1433 --name sqlserver1 -d microsoft/mssql-server-linux:2017-latest
I created two docker containers based on two different images. One of db and another for webserver. Both containers are running on my mac osx.
I can access db container from host machine and same way can access webserver from host machine.
However, how do I access db connection from webserver?
The way I started db container is
docker run --name oracle-db -p 1521:1521 -p 5501:5500 oracle/database:12.1.0.2-ee
I started wls container as
docker run --name oracle-wls -p 7001:7001 wls-image:latest
I can access db on host by connecting to
sqlplus scott/welcome1#//localhost:1521/ORCLCDB
I can access wls on host as
http://localhost:7001/console
It's easy.
If you have two or more running container, complete next steps:
docker network create myNetwork
docker network connect myNetwork web1
docker network connect myNetwork web2
Now you connect from web1 to web2 container or the other way round.
Use the internal network IP addresses which you can find by running:
docker network inspect myNetwork
Note that only internal IP addresses and ports are accessible to the containers connected by the network bridge.
So for example assuming that web1 container was started with: docker run -p 80:8888 web1 (meaning that its server is running on port 8888 internally), and inspecting myNetwork shows that web1's IP is 172.0.0.2, you can connect from web2 to web1 using curl 172.0.0.2:8888).
Easiest way is to use --link, however the newer versions of docker are moving away from that and in fact that switch will be removed soon.
The link below offers a nice how too, on connecting two containers. You can skip the attach portion, since that is just a useful how to on adding items to images.
https://web.archive.org/web/20160310072132/https://deis.com/blog/2016/connecting-docker-containers-1/
The part you are interested in is the communication between two containers. The easiest way, is to refer to the DB container by name from the webserver container.
Example:
you named the db container db1 and the webserver container web0. The containers should both be on the bridge network, which means the web container should be able to connect to the DB container by referring to its name.
So if you have a web config file for your app, then for DB host you will use the name db1.
if you are using an older version of docker, then you should use --link.
Example:
Step 1: docker run --name db1 oracle/database:12.1.0.2-ee
then when you start the web app. use:
Step 2: docker run --name web0 --link db1 webapp/webapp:3.0
and the web app will be linked to the DB. However, as I said the --link switch will be removed soon.
I'd use docker compose instead, which will build a network for you. However; you will need to download docker compose for your system. https://docs.docker.com/compose/install/#prerequisites
an example setup is like this:
file name is base.yml
version: "2"
services:
webserver:
image: moodlehq/moodle-php-apache:7.1
depends_on:
- db
volumes:
- "/var/www/html:/var/www/html"
- "/home/some_user/web/apache2_faildumps.conf:/etc/apache2/conf-enabled/apache2_faildumps.conf"
environment:
MOODLE_DOCKER_DBTYPE: pgsql
MOODLE_DOCKER_DBNAME: moodle
MOODLE_DOCKER_DBUSER: moodle
MOODLE_DOCKER_DBPASS: "m#0dl3ing"
HTTP_PROXY: "${HTTP_PROXY}"
HTTPS_PROXY: "${HTTPS_PROXY}"
NO_PROXY: "${NO_PROXY}"
db:
image: postgres:9
environment:
POSTGRES_USER: moodle
POSTGRES_PASSWORD: "m#0dl3ing"
POSTGRES_DB: moodle
HTTP_PROXY: "${HTTP_PROXY}"
HTTPS_PROXY: "${HTTPS_PROXY}"
NO_PROXY: "${NO_PROXY}"
this will name the network a generic name, I can't remember off the top of my head what that name is, unless you use the --name switch.
IE docker-compose --name setup1 up base.yml
NOTE: if you use the --name switch, you will need to use it when ever calling docker compose, so docker-compose --name setup1 down this is so you can have more then one instance of webserver and db, and in this case, so docker compose knows what instance you want to run commands against; and also so you can have more then one running at once. Great for CI/CD, if you are running test in parallel on the same server.
Docker compose also has the same commands as docker so docker-compose --name setup1 exec webserver do_some_command
best part is, if you want to change db's or something like that for unit test you can include an additional .yml file to the up command and it will overwrite any items with similar names, I think of it as a key=>value replacement.
Example:
db.yml
version: "2"
services:
webserver:
environment:
MOODLE_DOCKER_DBTYPE: oci
MOODLE_DOCKER_DBNAME: XE
db:
image: moodlehq/moodle-db-oracle
Then call docker-compose --name setup1 up base.yml db.yml
This will overwrite the db. with a different setup. When needing to connect to these services from each container, you use the name set under service, in this case, webserver and db.
I think this might actually be a more useful setup in your case. Since you can set all the variables you need in the yml files and just run the command for docker compose when you need them started. So a more start it and forget it setup.
NOTE: I did not use the --port command, since exposing the ports is not needed for container->container communication. It is needed only if you want the host to connect to the container, or application from outside of the host. If you expose the port, then the port is open to all communication that the host allows. So exposing web on port 80 is the same as starting a webserver on the physical host and will allow outside connections, if the host allows it. Also, if you are wanting to run more then one web app at once, for whatever reason, then exposing port 80 will prevent you from running additional webapps if you try exposing on that port as well. So, for CI/CD it is best to not expose ports at all, and if using docker compose with the --name switch, all containers will be on their own network so they wont collide. So you will pretty much have a container of containers.
UPDATE: After using features further and seeing how others have done it for CICD programs like Jenkins. Network is also a viable solution.
Example:
docker network create test_network
The above command will create a "test_network" which you can attach other containers too. Which is made easy with the --network switch operator.
Example:
docker run \
--detach \
--name db1 \
--network test_network \
-e MYSQL_ROOT_PASSWORD="${DBPASS}" \
-e MYSQL_DATABASE="${DBNAME}" \
-e MYSQL_USER="${DBUSER}" \
-e MYSQL_PASSWORD="${DBPASS}" \
--tmpfs /var/lib/mysql:rw \
mysql:5
Of course, if you have proxy network settings you should still pass those into the containers using the "-e" or "--env-file" switch statements. So the container can communicate with the internet. Docker says the proxy settings should be absorbed by the container in the newer versions of docker; however, I still pass them in as an act of habit. This is the replacement for the "--link" switch which is going away. Once the containers are attached to the network you created you can still refer to those containers from other containers using the 'name' of the container. Per the example above that would be db1. You just have to make sure all containers are connected to the same network, and you are good to go.
For a detailed example of using network in a cicd pipeline, you can refer to this link:
https://git.in.moodle.com/integration/nightlyscripts/blob/master/runner/master/run.sh
Which is the script that is ran in Jenkins for a huge integration tests for Moodle, but the idea/example can be used anywhere. I hope this helps others.
You will have to access db through the ip of host machine, or if you want to access it via localhost:1521, then run webserver like -
docker run --net=host --name oracle-wls wls-image:latest
See here
Using docker-compose, services are exposed to each other by name by default. Docs.
You could also specify an alias like;
version: '2.1'
services:
mongo:
image: mongo:3.2.11
redis:
image: redis:3.2.10
api:
image: some-image
depends_on:
- mongo
- solr
links:
- "mongo:mongo.openconceptlab.org"
- "solr:solr.openconceptlab.org"
- "some-service:some-alias"
And then access the service using the specified alias as a host name, e.g mongo.openconceptlab.org for mongo in this case.
Environment: Windows 10, Docker Desktop version 4.5.1.
Use hostname host.docker.internal to access services running on your host machine from inside a container.
See: https://docs.docker.com/desktop/windows/networking/#use-cases-and-workarounds
I run PostgreSQL in one container and my app in a separate container.
I configure the app database connection to use host.docker.internal as the hostname and it just works.
Consider Example
We Create two containers here PostgreSQL server and pgadmin(for accessing servers like PHPMyAdmin, SQL studio, workbench).
Exposed port
PostgreSql --->5436
Pgadmin --->5050
After adding a server in pgadmin hostname as localhost.It will show a connection error. Because Docker container pgadmin getting localhost as their system instead we need PostgreSQL IP to solve the problem.
docker network create con
docker network connect con app1
docker network connect con app2
This command gets connected container IP address and other details.
docker network inspect con
Now you can see the IP address shown in the network inspect. Choose the Postgres container IP. You can access other exposed ports through this IP. Here postgre 5432 is only exposed.Now set hostname as the container ip and it will work.
You can use the default docker network. If you don't want to go through any docker networking, you can do this:
Copy the ip address in Docker subnet in Resources>Network in Docker Preferences in Mac:
Docker preferences screenshot
As you can see from the screenshot link the ip address is
192.168.65.0
You just need to replace “localhost” in your containers config file with “192.168.65.1" (i.e. IP address picked + 1 ).
You can start your containers and should be set for local development/testing.
For some more details, you can see my article:
Connect Docker containers the easy way
In my case, the host connection in the application to a container from an other container by the IP provide by the bridge didn't work.
But it works with the name of the container (see my screenshot).
So you can replace the IP by the name of the container.