How does one add something new to an already existing docker image?
My goal here is to answer the three different questions asked as I understand them. This is only due to a lack of con on my part You Don I believe by already installed you mean that the be the basis for production operations? If you break process to add a package easily then you have all sorts of ways to get into an inconsistent state going forward. Better to re-create the then you have missed a key paradigm with Docker immutability. While it is possible to alter things on the fly it is considered an anti-pattern. Containers are not servers. Quick and Dirty If you are asking because you are developing something and you just see if adding the pip package will fix a problem then just `docker exec` into the running container and add the package. Validate your hypothesis then immediately alter the Dockerfile that describes the and try something new. Disposability is a key value proposition for using Docker as the basis of a development environment. Arguable Best Practice It was suggested to create a new Dockerfile and start with the existing . Maybe you even push it to an . In my personal religion it is even worse that you are not deriving you image from canonical base. However as a python developer you are violating the zen that states Favor explicit over implicit. And this is where the problemes in. The Dockerfile should be an explicit highlymented description of the runtime environment for the python service. To that end it should explicitly state every pip package - and its version - needed to run. So my rmendation would be to have a `` file in the root of your project. As part of the Dockerfile import that and run `pip install` against it. If you need to add a package remove a package or change a version it happens there. Finally when you make these changes they will be clear in the history of your source control tool (along with that excellentmit message you wrote about why you made the change) in case there is trouble down stream. Please keep in mind this is my take. Take it all and consider you situation. Apply a grain of salt and your own con. Best of luck.
How does a docker commit work?
Im assuming that you are asking this question to understand the workings of the dockermit mand available in docker but first you have to understand how does docker name you will get all the layers of the docker layers . This writable layer allows you to make changes to the container since the lower layers in the by using union file system. union file systembines the directories(layers) and make it look like single directory. As dockermit use to save the state of running container and As I said earlier last layer is writable . so when we run dockermit with container name and tag for the specific running container. It will generate the new layer from the last writable layer. then it will store those layers hierarchy under the image name we have provided. Hope this helps!
How do I Dockerize a Java microservice? Explain with examples.
Question at time of answer How do I Dockerize a Java microservice? Ex with examples. italic First off Ill make some assumptions You have a Java microservice that you can run with java -jar code The service listens on port 88 when running You have installed docker Install Docker s Next you will want to create a docker and thereby creating your own. So we need an that we are running on this port code EXPOSE 88 code code # copies the file to the working dir in the code CMD java -jar code Now we need to actually build the based on the contents of this italic directory. It is possible to have the Dockerfile in another directory than the jar file by doing something like this (imagine jar file in target subdir and Dockerfile next to your in a maven project) docker build -f Dockerfile target code Now the output from the above call (in both forms) is something like this Sending build con to Docker daemon code Step 1 FROM openjdkjre code jre Pulling from library code c73ab1c6897b Pullplete code 1ab373b3deae Pullplete code ... code 98293be24d Pullplete code Digest sha25692e215e4c5f832f21f6abe4ab6b7bb6c37aa5e3267a42566e9c5499addaab4 code Status Downloaded newer and then performed our three additions. The end result is a container with the lyrical easy to remember name 1187655728a4. Granted it doesn really roll off the tongue so we can give it a new name (we could have added a -t parameter above as well) by using the tagmand docker tag 1187655728a4 service_v1 code docker run -d -p 8988 service_imagev1 code Here were telling docker to start our container twice. Were telling it to detach immediately (-d) which means to run the containers in the background. Also were instructing it to forward port 88 in the container to ports 88 (for the first one) and 89 (for the second one). The two services are now running in parallel each on a different port. You can test this with for instance ie s (here Ive started a small spring boot hello world example) $ 89 code HTTP 2 code Content-Length 27 code Content-Type ;charset=UTF-8 code Date Tue 1 Apr 218 25948 GMT code code Greetings from Spring Boot! code code $ 88 code HTTP 2 code Content-Length 27 code Content-Type ;charset=UTF-8 code Date Tue 1 Apr 218 25951 GMT code code Greetings from Spring Boot! code To see more info about those containers use docker ps # shows running containers. Note the name at the end. code docker logs
How is Docker's development moving so fast?
Docker development has grown this quick because of what it has in the offering. Because it can be adopted by almost anypany. AND if there arepanies which are not able to adopt it right now then its just a short wait for them. Because every now and then there is a new version and each version is much more useful than the previous one. So a lot of folks who have not given enough appreciation for Docker have changed their opinion. But enough with this sales pitch let me ex technology-wise why Docker is the goto containerization & deployment tool. Docker can containerize just about anything in the DevOps lifecycle. Before I ex what it can containerize let me tell you why anything is containerized. Because containerization makes the software application Light-weight . Less processing on the servers. Faster. Response time for boot-up is very less. Scalability . Onemand for increasing decreasing the no. of instances. Reliability . Consistent environment results in lesser production probs. Shipping . Easily transportable. If your not able to relate to any of these points check out this video I recorded. s Also you can read this blog Docker Tutorial | Introduction To Docker & Containerization | Edureka s . Getting back to what can Docker containerize? It can just about containerize anything and everything. Can Dockerize all top IT technologies. Like Splunk Jenkins and a 1 more ordered-list I rest my case here. You canment any disagreements doubts. Happy learning )
If Docker is written in Go, then why does Python run when Docker images are started?
Each container model is built differently from another. A Python container would import in it's Dockerfile the s include multiple ONBUILD triggers which should be all you need to bootstrap most applications. The build will COPY a file RUN pip install on said file and then copy the current directory into You can then build and run the Docker imagendocker build -t my-python-app . docker run -it --rm --name my-running-app my-python-app
How do I create a CentOS Docker image?
Others have given details of how to create the and build something (really creating a container not an 'centoslatest' locally code latest Pulling from library code
What is -t in a docker build command?
-t is used for tagging the to docker hub. Basically a name version
How do I run multiple docker containers with single database container?
I got a answer for my question!!! For testing i was used following repo 2 Download CenturyLinkLabs s docker-mysql s git clone CenturyLinkLabs s 2Do changes in run(script file) like set -e Chown -R mysqlmysql mysql_install_db --user mysql MYSQL_ROOT_PASSWORD=$MYSQL_ROOT_PASSWORD- MYSQL_DATABASE_1=$MYSQL_DATABASE_1- MYSQL_DATABASE_2=$MYSQL_DATABASE_2- MYSQL_USER=$MYSQL_USER- MYSQL_PASSWORD=$MYSQL_PASSWORD- tfile=`mktemp` if ! -f $tfile ; then return 1 fi cat << EOF $tfile USE mysql; FLUSH PRIVILEGES; GRANT ALL PRIVILEGES ON *.* TO 'root'@'%' WITH GRANT OPTION; UPDATE user SET password=PASSWORD($MYSQL_ROOT_PASSWORD) WHERE user='root'; EOF if $MYSQL_DATABASE_1 != ; then echo CREATE DATABASE IF NOT EXISTS `$MYSQL_DATABASE_1` CHARACTER SET utf8 COLLATE utf8_general_ci; $tfile if $MYSQL_USER != ; then echo GRANT ALL ON `$MYSQL_DATABASE_1`.* to '$MYSQL_USER'@'%' IDENTIFIED BY '$MYSQL_PASSWORD'; $tfile fi fi if $MYSQL_DATABASE_2 != ; then echo CREATE DATABASE IF NOT EXISTS `$MYSQL_DATABASE_2` CHARACTER SET utf8 COLLATE utf8_general_ci; $tfile if $MYSQL_USER != ; then echo GRANT ALL ON `$MYSQL_DATABASE_2`.* to '$MYSQL_USER'@'%' IDENTIFIED BY '$MYSQL_PASSWORD'; $tfile fi fi --bootstrap --verbose= < $tfile rm -f $tfile exec 2 build mysql server locally docker build -t mydbserver . 2Now mysql server with moodle1 name 2docker run -d -P --name moodle-hyd -- moodledbserverDB -e MOODLE_URL= -p 888 moodle1 2now moodle-hyd is running with moodle1 databse 2 Do chages file like below $CFG-dbname = getenv('DB_ENV_MYSQL_DATABASE_2') 2now build docker build -t moodle2 . 2 now you are able to see image with moodle2 name 2docker run -d -P --name moodle-mum -- moodledbserverDB -e MOODLE_URL= 1 -p 8818 moodle1 2 now moodle-mum is running with moodle2 databse if any queries feel free toment below Thank you
How do I choose docker images?
Docker hub s is the centralized docker repository maintained by the Docker inc. The purpose of this repository to share distribute docker s are available in docker hub. If the s can be build with simplemand( docker build italic ). Thismand takes input as a dockerfile italic where instructions about the docker . Using docker build italic can create an automated build that executes severalmand-line instructions in succession. The detail instruction on how to write a dockerfile and subsequent instruction to build the is created it can be pushed to the Docker hub the centralized repository in order to make it available to other developers. For that you need to create an account in docker hub and subsequently push the for example Ubuntu s es with the basic packages. You can go to the site of the size of the and find all the available and choose the right one.