I've got a directory called thing with my docker compose project:
thing
├── Dockerfile
└── docker-compose.yml
The contents of docker-compose.yml:
master:
build: .
Whenver I run docker-compose build in this folder, this will produce a docker image called thing_master. I'd like to specify in docker-compose.yml another name for my image. Is this possible?
– I know I can run docker-compose -p [image_name] build or set the environment variable COMPOSE_PROJECT_NAME, but that's not what I wish to do.
This is now possible in Compose 1.6 (rc2 is out now).
Using 1.6, you can have both build and image on the same service:
version: "2"
services:
master:
build: .
image: my_image_name:my_tag
Build will use the image name to tag the image.
Related
I am trying to build an image with docker compose and it fails, however it works with just docker. I have read some SO posts saying that the error thrown when failing happens when a file/folder cannot be found in the Dockerfile. The build works when building with docker so I dont know why it wouldn't work with docker-compose. Why is this happening?
The structure for this project is this:
parent_proj
|_proj
|_Dockerfile
|_docker-compose.yml
Here is my docker-compose file:
version: '3.4'
services:
integrations:
build:
context: .
dockerfile: proj/Dockerfile
network: host
image: int
ports:
- "5000:5000"
Here is the Dockerfile inside proj/
FROM openjdk:11
USER root
#RUN apt-get bash
ARG JAR_FILE=target/proj-0.0.1-SNAPSHOT.jar
COPY ${JAR_FILE} /app2.jar
ENTRYPOINT ["java","-jar", "/app2.jar"]
When I'm inside the proj folder. I can run
docker build . -t proj
The above succeeds and I can subsequently run the container. However when I am in parent_proj and run docker compose build it fails with the error message
failed to compute cache key: failed to walk
/var/lib/docker/tmp/buildkit-mount316454722/target: lstat
/var/lib/docker/tmp/buildkit-mount316454722/target: no such file or
directory
Why does this happen? How can I build successfully with docker-compose without restructuring the project?
thanks
Your Compose build options and the docker build options you show are different. The successful command is (where -f Dockerfile is the default):
docker build ./proj -t proj # -f Dockerfile
# context: image: dockerfile:
But your Compose setup is running
docker build . -t img -f proj/Dockerfile
# context: image: dockerfile:
Which one is right? In the Dockerfile, you
COPY target/proj-0.0.1-SNAPSHOT.jar /some/container/path
That target/... source path is always relative to the build-context directory (Compose context: option, the directory parameter to docker build), even if it looks like an absolute path and even if the Dockerfile is in a different directory. If that target directory is a subdirectory of proj then you need the first form.
There's a shorthand Compose build: syntax if the only thing you need to specify is the context directory, and I'd use that here. If you don't specifically care what the image name is (you're not pushing it to a registry) then Compose can pick a reasonable name on its own; you don't need to specify image:.
version: '3.8'
services:
integrations:
build: ./proj
ports:
- "5000:5000"
I have 2 services: nginx and web
When I build web image I build the frontend via the command npm install && npm run build
But I need prepared files in both containers: in the web and in the nginx.
How to share files between containers (images)? I can't simply use volumes, because they will be mounted only in runtime.
The Dockerfile COPY directive can copy files from an arbitrary image. While it's most commonly used in multi-stage builds, you can use it with any image, even one you built yourself.
Say your docker-compose.yml file looks like:
version: '3.8'
services:
web:
build: .
image: my/web
nginx:
build:
context: .
dockerfile: Dockerfile.nginx
ports: [8000:80]
Note that we've explicitly given the web image a name; also notice that there are no volumes: in this setup.
In the proxy image, we can then copy files out of that image:
# Dockerfile.nginx
FROM nginx
COPY --from=my/web /app/static /usr/share/nginx/html
The only complication here is that Compose doesn't know that one image is built off of the other. You'll probably have to manually tell it to rebuild the application image so that it gets built before the proxy image.
docker-compose build web
docker-compose build
docker-compose up -d
You can use this in a more production-oriented setup to deploy this application without having the code directly available. You can create a base docker-compose.yml that names an image: for both containers, and then add a separate docker-compose.override.yml file that has the build: blocks. After running docker-compose build twice as above, you can docker-compose push the built images, and then run this container stack on your production system getting the images from the registry; without a local copy of the source tree and without volumes.
I am trying to come up with a CI system where I validate the Dockerfile and docker-compose.yaml files that are used to build our images.
I found Google containter-structure-tests
that can be used to verify the structre of Docker images that are built. This works if the docker images are build from Dockerfile.
Is there a way that I can verify the docker images with all the configurations that are added to the images by Docker-compose?
EDIT:
Maybe I didn't all put all my details into the questions.
Lets say I have docker-compose file with the following structure:
version: "3"
services:
image-a:
build:
context: .
dockerfile: Dockerfile-a
image-b:
build:
context: .
dockerfile: Dockerfile-b
ports:
- '8983:8983'
volumes:
- '${DEV_ENV_ROOT}/solr/cores:/var/data/solr'
- '${DEV_ENV_SOLR_ROOT}/nginx:/var/lib/nginx'
Now that the images would be built from Dockerfile-a and Dockerfile-b, there would be configurations made on top of image foo-b. How can I validate those configurations without building the container from image foo-b? Would that even be possible?
Assuming you have the following docker-compose.yml file:
version: "3"
services:
image-a:
build:
context: .
dockerfile: Dockerfile-a
image-b:
build:
context: .
dockerfile: Dockerfile-b
Build your images running the command docker-compose --project-name foo build. This will make all images' name start with the prefix foo_. So you would end up with the following image names:
foo_image-a
foo_image-b
The trick is to use a unique id (such as your CI job id) instead of foo so you can identify the very images that were just built.
Now that you know the names of your images, you can use:
container-structure-test test --image foo_image-a --config config.yaml
container-structure-test test --image foo_image-b --config config.yaml
If you are to make some kind of generic job which does not know the docker compose service names, you can use the following command to get the list of images starting with that foo_ prefix:
docker image list --filter "reference=foo_*"
REPOSITORY TAG IMAGE ID CREATED SIZE
foo_image-a latest 0c5e1cf8c1dc 16 minutes ago 4.15MB
foo_image-b latest d4e384157afb 16 minutes ago 4.15MB
and if you want a script to iterate over this result, add the --quiet option to obtain just the images' id:
docker image list --filter "reference=foo_*" --quiet
0c5e1cf8c1dc
d4e384157afb
I am following lynda Docker tutorials and performing stuff related to docker compose file.
This is my docker-compose.yml file.
more docker-compose.yml
version: '3'
services:
web:
image: jboss/wildfly
volumes:
- ~/deployments:/opt/jboss/wildfly/standalone/deployments
ports:
- 8080:8080
As per authors, I am trying to copy webapp.war file to deployments/ folder giving me error. It look like volume mapping for the docker file is not working.
cp /home/user/Demos/docker-for-java/chapter2/webapp.war deployments/
cp: cannot create regular file ‘deployments/’: Not a directory
docker-compose ps
Name Command State Ports
--------------------------------------------------------------------------------
helloweb_web_1 /opt/jboss/wildfly/bin/sta ... Up 0.0.0.0:8080->8080/tcp
I think you might be misinterpreting tutorial. I haven't seen the tutorial itself, but checking the documentation for the WildFly Docker image here there's a mention that you need to extend base image and add your war file inside:
To do this you just need to extend the jboss/wildfly image by creating a new one. Place your application inside the deployments/ directory with the ADD command (but make sure to include the trailing slash on the deployment folder path, more info). You can also do the changes to the configuration (if any) as additional steps (RUN command).
This means that you need to create a Dockerfile with approximately this contents (change your-awesome-app.war with the path to your war file):
FROM jboss/wildfly
ADD your-awesome-app.war /opt/jboss/wildfly/standalone/deployments/
After that you need to change you docker-compose.yml to build from your Dockerfile instead of using jboss/wildfly (note the use of build: . instead of image: jboss/wildfly):
version: '3'
services:
web:
build: .
ports:
- 8080:8080
Try that and comment if you run into any issues
What is the difference between docker-compose build and docker build?
Suppose in a dockerized project path there is a docker-compose.yml file:
docker-compose build
And
docker build
docker-compose can be considered a wrapper around the docker CLI (in fact it is another implementation in python as said in the comments) in order to gain time and avoid 500 characters-long lines (and also start multiple containers at the same time). It uses a file called docker-compose.yml in order to retrieve parameters.
You can find the reference for the docker-compose file format here.
So basically docker-compose build will read your docker-compose.yml, look for all services containing the build: statement and run a docker build for each one.
Each build: can specify a Dockerfile, a context and args to pass to docker.
To conclude with an example docker-compose.yml file :
version: '3.2'
services:
database:
image: mariadb
restart: always
volumes:
- ./.data/sql:/var/lib/mysql
web:
build:
dockerfile: Dockerfile-alpine
context: ./web
ports:
- 8099:80
depends_on:
- database
When calling docker-compose build, only the web target will need an image to be built. The docker build command would look like :
docker build -t web_myproject -f Dockerfile-alpine ./web
docker-compose build will build the services in the docker-compose.yml file.
https://docs.docker.com/compose/reference/build/
docker build will build the image defined by Dockerfile.
https://docs.docker.com/engine/reference/commandline/build/
Basically, docker-compose is a better way to use docker than just a docker command.
If the question here is if docker-compose build command, will build a zip kind of thing containing multiple images, which otherwise would have been built separately with usual Dockerfile, then the thinking is wrong.
Docker-compose build, will build individual images, by going into individual service entry in docker-compose.yml.
With docker images, command, we can see all the individual images being saved as well.
The real magic is docker-compose up.
This one will basically create a network of interconnected containers, that can talk to each other with name of container similar to a hostname.
Adding to the first answer...
You can give the image name and container name under the service definition.
e.g. for the service called 'web' in the below docker-compose example, you can give the image name and container name explicitly, so that docker does not have to use the defaults.
Otherwise the image name that docker will use will be the concatenation of the folder (Directory) and the service name. e.g. myprojectdir_web
So it is better to explicitly put the desired image name that will be generated when docker build command is executed.
e.g.
image: mywebserviceImage
container_name: my-webServiceImage-Container
example docker-compose.yml file :
version: '3.2'
services:
web:
build:
dockerfile: Dockerfile-alpine
context: ./web
ports:
- 8099:80
image: mywebserviceImage
container_name: my-webServiceImage-Container
depends_on:
- database
Few additional words about the difference between docker build and docker-compose build.
Both have an option for building images using an existing image as a cache of layers.
with docker build, the option is --cache-from <image>
with docker-composer, there is a tag cache_from in the build section.
Unfortunately, up until now, at this level, images made by one are not compatible with the other as a cache of layers (Ids are not compatible).
However, docker-compose v1.25.0 (2019-11-18), introduces an experimental feature COMPOSE_DOCKER_CLI_BUILD so that docker-compose uses native docker builder (therefore, images made by docker build can be used as a cache of layers for docker-compose build)