How can I include files from outside of Docker's build context using the "ADD" command in the Docker file?
From the Docker documentation:
The path must be inside the context of the build; you cannot ADD
../something/something, because the first step of a docker build is to
send the context directory (and subdirectories) to the docker daemon.
I do not want to restructure my whole project just to accommodate Docker in this matter. I want to keep all my Docker files in the same sub-directory.
Also, it appears Docker does not yet (and may not ever) support symlinks: Dockerfile ADD command does not follow symlinks on host #1676.
The only other thing I can think of is to include a pre-build step to copy the files into the Docker build context (and configure my version control to ignore those files). Is there a better workaround for than that?
The best way to work around this is to specify the Dockerfile independently of the build context, using -f.
For instance, this command will give the ADD command access to anything in your current directory.
docker build -f docker-files/Dockerfile .
Update: Docker now allows having the Dockerfile outside the build context (fixed in 18.03.0-ce). So you can also do something like
docker build -f ../Dockerfile .
I often find myself utilizing the --build-arg option for this purpose. For example after putting the following in the Dockerfile:
ARG SSH_KEY
RUN echo "$SSH_KEY" > /root/.ssh/id_rsa
You can just do:
docker build -t some-app --build-arg SSH_KEY="$(cat ~/file/outside/build/context/id_rsa)" .
But note the following warning from the Docker documentation:
Warning: It is not recommended to use build-time variables for passing secrets like github keys, user credentials etc. Build-time variable values are visible to any user of the image with the docker history command.
I spent a good time trying to figure out a good pattern and how to better explain what's going on with this feature support. I realized that the best way to explain it was as follows...
Dockerfile: Will only see files under its own relative path
Context: a place in "space" where the files you want to share and your Dockerfile will be copied to
So, with that said, here's an example of the Dockerfile that needs to reuse a file called start.sh
Dockerfile
It will always load from its relative path, having the current directory of itself as the local reference to the paths you specify.
COPY start.sh /runtime/start.sh
Files
Considering this idea, we can think of having multiple copies for the Dockerfiles building specific things, but they all need access to the start.sh.
./all-services/
/start.sh
/service-X/Dockerfile
/service-Y/Dockerfile
/service-Z/Dockerfile
./docker-compose.yaml
Considering this structure and the files above, here's a docker-compose.yml
docker-compose.yaml
In this example, your shared context directory is the runtime directory.
Same mental model here, think that all the files under this directory are moved over to the so-called context.
Similarly, just specify the Dockerfile that you want to copy to that same directory. You can specify that using dockerfile.
The directory where your main content is located is the actual context to be set.
The docker-compose.yml is as follows
version: "3.3"
services:
service-A
build:
context: ./all-service
dockerfile: ./service-A/Dockerfile
service-B
build:
context: ./all-service
dockerfile: ./service-B/Dockerfile
service-C
build:
context: ./all-service
dockerfile: ./service-C/Dockerfile
all-service is set as the context, the shared file start.sh is copied there as well the Dockerfile specified by each dockerfile.
Each gets to be built their own way, sharing the start file!
On Linux you can mount other directories instead of symlinking them
mount --bind olddir newdir
See https://superuser.com/questions/842642 for more details.
I don't know if something similar is available for other OSes.
I also tried using Samba to share a folder and remount it into the Docker context which worked as well.
If you read the discussion in the issue 2745 not only docker may never support symlinks they may never support adding files outside your context. Seems to be a design philosophy that files that go into docker build should explicitly be part of its context or be from a URL where it is presumably deployed too with a fixed version so that the build is repeatable with well known URLs or files shipped with the docker container.
I prefer to build from a version controlled source - ie docker build
-t stuff http://my.git.org/repo - otherwise I'm building from some random place with random files.
fundamentally, no.... -- SvenDowideit, Docker Inc
Just my opinion but I think you should restructure to separate out the code and docker repositories. That way the containers can be generic and pull in any version of the code at run time rather than build time.
Alternatively, use docker as your fundamental code deployment artifact and then you put the dockerfile in the root of the code repository. if you go this route probably makes sense to have a parent docker container for more general system level details and a child container for setup specific to your code.
I believe the simpler workaround would be to change the 'context' itself.
So, for example, instead of giving:
docker build -t hello-demo-app .
which sets the current directory as the context, let's say you wanted the parent directory as the context, just use:
docker build -t hello-demo-app ..
You can also create a tarball of what the image needs first and use that as your context.
https://docs.docker.com/engine/reference/commandline/build/#/tarball-contexts
This behavior is given by the context directory that the docker or podman uses to present the files to the build process.
A nice trick here is by changing the context dir during the building instruction to the full path of the directory, that you want to expose to the daemon.
e.g:
docker build -t imageName:tag -f /path/to/the/Dockerfile /mysrc/path
using /mysrc/path instead of .(current directory), you'll be using that directory as a context, so any files under it can be seen by the build process.
This example you'll be exposing the entire /mysrc/path tree to the docker daemon.
When using this with docker the user ID who triggered the build must have recursively read permissions to any single directory or file from the context dir.
This can be useful in cases where you have the /home/user/myCoolProject/Dockerfile but want to bring to this container build context, files that aren't in the same directory.
Here is an example of building using context dir, but this time using podman instead of docker.
Lets take as example, having inside your Dockerfile a COPY or ADDinstruction which is copying files from a directory outside of your project, like:
FROM myImage:tag
...
...
COPY /opt/externalFile ./
ADD /home/user/AnotherProject/anotherExternalFile ./
...
In order to build this, with a container file located in the /home/user/myCoolProject/Dockerfile, just do something like:
cd /home/user/myCoolProject
podman build -t imageName:tag -f Dockefile /
Some known use cases to change the context dir, is when using a container as a toolchain for building your souce code.
e.g:
podman build --platform linux/s390x -t myimage:mytag -f ./Dockerfile /tmp/mysrc
or it can be a path relative, like:
podman build --platform linux/s390x -t myimage:mytag -f ./Dockerfile ../../
Another example using this time a global path:
FROM myImage:tag
...
...
COPY externalFile ./
ADD AnotherProject ./
...
Notice that now the full global path for the COPY and ADD is omitted in the Dockerfile command layers.
In this case the contex dir must be relative to where the files are, if both externalFile and AnotherProject are in /opt directory then the context dir for building it must be:
podman build -t imageName:tag -f ./Dockerfile /opt
Note when using COPY or ADD with context dir in docker:
The docker daemon will try to "stream" all the files visible on the context dir tree to the daemon, which can slowdown the build. And requires the user to have recursively permission from the context dir.
This behavior can be more costly specially when using the build through the API. However,with podman the build happens instantaneously, without needing recursively permissions, that's because podman does not enumerate the entire context dir, and doesn't use a client/server architecture as well.
The build for such cases can be way more interesting to use podman instead of docker, when you face such issues using a different context dir.
Some references:
https://docs.docker.com/engine/reference/commandline/build/
https://docs.podman.io/en/latest/markdown/podman-build.1.html
As is described in this GitHub issue the build actually happens in /tmp/docker-12345, so a relative path like ../relative-add/some-file is relative to /tmp/docker-12345. It would thus search for /tmp/relative-add/some-file, which is also shown in the error message.*
It is not allowed to include files from outside the build directory, so this results in the "Forbidden path" message."
Using docker-compose, I accomplished this by creating a service that mounts the volumes that I need and committing the image of the container. Then, in the subsequent service, I rely on the previously committed image, which has all of the data stored at mounted locations. You will then have have to copy these files to their ultimate destination, as host mounted directories do not get committed when running a docker commit command
You don't have to use docker-compose to accomplish this, but it makes life a bit easier
# docker-compose.yml
version: '3'
services:
stage:
image: alpine
volumes:
- /host/machine/path:/tmp/container/path
command: bash -c "cp -r /tmp/container/path /final/container/path"
setup:
image: stage
# setup.sh
# Start "stage" service
docker-compose up stage
# Commit changes to an image named "stage"
docker commit $(docker-compose ps -q stage) stage
# Start setup service off of stage image
docker-compose up setup
Create a wrapper docker build shell script that grabs the file then calls docker build then removes the file.
a simple solution not mentioned anywhere here from my quick skim:
have a wrapper script called docker_build.sh
have it create tarballs, copy large files to the current working directory
call docker build
clean up the tarballs, large files, etc
this solution is good because (1.) it doesn't have the security hole from copying in your SSH private key (2.) another solution uses sudo bind so that has another security hole there because it requires root permission to do bind.
I think as of earlier this year a feature was added in buildx to do just this.
If you have dockerfile 1.4+ and buildx 0.8+ you can do something like this
docker buildx build --build-context othersource= ../something/something .
Then in your docker file you can use the from command to add the context
ADD –from=othersource . /stuff
See this related post https://www.docker.com/blog/dockerfiles-now-support-multiple-build-contexts/
Workaround with links:
ln path/to/file/outside/context/file_to_copy ./file_to_copy
On Dockerfile, simply:
COPY file_to_copy /path/to/file
I was personally confused by some answers, so decided to explain it simply.
You should pass the context, you have specified in Dockerfile, to docker when
want to create image.
I always select root of project as the context in Dockerfile.
so for example if you use COPY command like COPY . .
first dot(.) is the context and second dot(.) is container working directory
Assuming the context is project root, dot(.) , and code structure is like this
sample-project/
docker/
Dockerfile
If you want to build image
and your path (the path you run the docker build command) is /full-path/sample-project/,
you should do this
docker build -f docker/Dockerfile .
and if your path is /full-path/sample-project/docker/,
you should do this
docker build -f Dockerfile ../
An easy workaround might be to simply mount the volume (using the -v or --mount flag) to the container when you run it and access the files that way.
example:
docker run -v /path/to/file/on/host:/desired/path/to/file/in/container/ image_name
for more see: https://docs.docker.com/storage/volumes/
I had this same issue with a project and some data files that I wasn't able to move inside the repo context for HIPAA reasons. I ended up using 2 Dockerfiles. One builds the main application without the stuff I needed outside the container and publishes that to internal repo. Then a second dockerfile pulls that image and adds the data and creates a new image which is then deployed and never stored anywhere. Not ideal, but it worked for my purposes of keeping sensitive information out of the repo.
In my case, my Dockerfile is written like a template containing placeholders which I'm replacing with real value using my configuration file.
So I couldn't specify this file directly but pipe it into the docker build like this:
sed "s/%email_address%/$EMAIL_ADDRESS/;" ./Dockerfile | docker build -t katzda/bookings:latest . -f -;
But because of the pipe, the COPY command didn't work. But the above way solves it by -f - (explicitly saying file not provided). Doing only - without the -f flag, the context AND the Dockerfile are not provided which is a caveat.
How to share typescript code between two Dockerfiles
I had this same problem, but for sharing files between two typescript projects. Some of the other answers didn't work for me because I needed to preserve the relative import paths between the shared code. I solved it by organizing my code like this:
api/
Dockerfile
src/
models/
index.ts
frontend/
Dockerfile
src/
models/
index.ts
shared/
model1.ts
model2.ts
index.ts
.dockerignore
Note: After extracting the shared code into that top folder, I avoided needing to update the import paths because I updated api/models/index.ts and frontend/models/index.ts to export from shared: (eg export * from '../../../shared)
Since the build context is now one directory higher, I had to make a few additional changes:
Update the build command to use the new context:
docker build -f Dockerfile .. (two dots instead of one)
Use a single .dockerignore at the top level to exclude all node_modules. (eg **/node_modules/**)
Prefix the Dockerfile COPY commands with api/ or frontend/
Copy shared (in addition to api/src or frontend/src)
WORKDIR /usr/src/app
COPY api/package*.json ./ <---- Prefix with api/
RUN npm ci
COPY api/src api/ts*.json ./ <---- Prefix with api/
COPY shared usr/src/shared <---- ADDED
RUN npm run build
This was the easiest way I could send everything to docker, while preserving the relative import paths in both projects. The tricky (annoying) part was all the changes/consequences caused by the build context being up one directory.
One quick and dirty way is to set the build context up as many levels as you need - but this can have consequences.
If you're working in a microservices architecture that looks like this:
./Code/Repo1
./Code/Repo2
...
You can set the build context to the parent Code directory and then access everything, but it turns out that with a large number of repositories, this can result in the build taking a long time.
An example situation could be that another team maintains a database schema in Repo1 and your team's code in Repo2 depends on this. You want to dockerise this dependency with some of your own seed data without worrying about schema changes or polluting the other team's repository (depending on what the changes are you may still have to change your seed data scripts of course)
The second approach is hacky but gets around the issue of long builds:
Create a sh (or ps1) script in ./Code/Repo2 to copy the files you need and invoke the docker commands you want, for example:
#!/bin/bash
rm -r ./db/schema
mkdir ./db/schema
cp -r ../Repo1/db/schema ./db/schema
docker-compose -f docker-compose.yml down
docker container prune -f
docker-compose -f docker-compose.yml up --build
In the docker-compose file, simply set the context as Repo2 root and use the content of the ./db/schema directory in your dockerfile without worrying about the path.
Bear in mind that you will run the risk of accidentally committing this directory to source control, but scripting cleanup actions should be easy enough.
When creating a file using the RUN command, any files created in the designated shared volume folder dissapear when they are trying to be accessed in the CMD command
Where the volumes are:
...
volumes:
- './hostpersist:/usr/src/app/persist'
e.g., the following Dockerfile does not create a file, the file is not visible by the index.js script, nor by the host filesystem
...
WORKDIR /usr/src/app
...
# creates file in persist/file.txt
RUN node migrate.js
# persist/file.txt does not exist
CMD [ "node", "index.js" ]
When putting both scripts to run in the CMD, the file is created and visible by index.js
...
# persist/file.txt exists
CMD node migrate.js && node index.js
Is there any way to keep file changes persistent without stuffing everything into CMD?
The volume is mounted AFTER the container is created (instantiated), thus overwriting the content you're creating during runtime of the container image (which is RUN do_something_on_/usr/src/app/persist).
If you leave out the volumes: declaration in your docker-compose file, you will see, that the files created by your node migrate.js call will be available in your container.
So, summing up, I'd go for the runtime installation, which is your CMD call to both node executions. These will definitely be called AFTER the container is created and your local host volume is mounted.
In my case, I am creating a config.json that I need to copy from the host to my container.
I figured out there is some option that I can pass args to my dockerfile.
so first step is :
1.create Dockerfile:
FROM golang
WORKDIR /go/src/app
COPY . . /* here we have /foo directory */
COPY $CONFIG_PATH ./foo/
EXPOSE $PORT
CMD ["./foo/run", "-config", "./foo/config.json"]
as you can see, I have 2 variable [ "$CONFIG_PATH", "$PORT"].
so these to variables are dynamic and comes from my command in docker run.
here I need to copy my config file from my host to my container, and I need to run my project with that config.json file.
after building image:
second step:
get my config file from user and run the docker image with these variables.
let configFilePath = '/home/baazz/baaaf/config.json'
let port = "8080"
docker.run('my_image', null, process.stdout, { Env: [`$CONFIG_PATH=${configFilePath}`, `$PORT=${port}`] }).then(data => {
}).catch(err => { console.log(err) })
I am getting this error message when I am trying to execute my code.
Error opening JSON configuration (./foo/config.json): open
./foo/config.json: no such file or directory . Terminating.
You generally don’t want to COPY configuration files like this in your Docker image. You should be able to docker run the same image in multiple environments without modification.
Instead, you can use the docker run -v option to inject the correct config file when you run the image:
docker run -v $PWD/config-dev.json:/go/src/app/foo/config.json my_image
(The Dockerode home page shows an equivalent Binds option. In Docker Compose, this goes into the per-container volumes:. There’s no requirement that the two paths or file names match.)
Since file paths like this become part of the external interface to how people run your container, you generally don’t want to make them configurable at build time. Pick a fixed path and document that that’s the place to mount your custom config file.
I have a docker image containing an NodeJS app. The Dockerfile is:
FROM node:8
WORKDIR /app
ADD . /app
RUN npm install
EXPOSE 80
ENTRYPOINT [ "/bin/sh", "./start.sh" ]
The start.sh script is:
#!/bin/bash
...
echo "Starting application"
npm start
I'm able to launch and test the image manually:
$ gcloud docker -- run -it --rm my-container
...
Starting application
...
> node index.js
...
The same container is used by a kubernetes deployment:
apiVersion: extensions/v1beta1
kind: Deployment
...
spec:
...
template:
...
spec:
containers:
- image: my-container
...
The container starts, the start.sh script is correctly executed but it terminates and the container goes into a CrashLoopBackOff loop.
After inspecting the pod manually:
kubectl exec -ti my-pod -- bash
I have no name!#my-pod:/app# cat /etc/passwd
... empty response
-> It appears that somehow there are no system users on the container, which makes most commands (like npm) fail silently and terminate the container
I have also tried, without success:
deleting the pod
deleting and re-creating the deployment
running the node image with the node user -> unable to find user node: no matching entries in passwd file
Last note: I actually have many deployments (using the same template with just a different name) which are running fine with an image that was built a few days ago with the same source code.
For some deployments, it actually worked after manually deleting the pod and letting kubernetes recreate it.
Any ideas?
Edit 18/01/2018 I have tried rebuilding an image with the same source code that old working images use, without success. I have also tried a simpler Dockerfile:
FROM node:8
USER node
But I still get an error related to the fact that no users seem to be there:
Error response from daemon: {"message":"linux spec user: unable to find user node: no matching entries in passwd file"}
I have checked with the docker-node guys, the image hasn't changed recently. Could it be related to kubernetes changes? Keep it mind that my images do run when I run them manually with the docker command.
I tried to reproduce your issue, but didn't get it to fail in anything like the same fashion. I made a dummy express app and stuck it on github that matches your example above, and then invoked it into a local minikube instance I had. The base image size is reasonably large, but it started up just fine.
I had to interpret what was happening within npm start for your example since you didn't specify, but you can see my package.json, which I suspect is pretty close to what you're doing based on the description.
When I fire this up:
git clone https://github.com/heckj/dummyexpress
cd dummyexpress
kubectl apply -f deploy/
The I got a running instance right off the bat:
NAME READY STATUS RESTARTS AGE
dummynodeapp-7788b95497-tkw2s 1/1 Running 0 1d
And the logs show pretty much what you'd expect:
**kubectl log dummynodeapp-7788b95497-tkw2s**
W0117 19:41:00.986498 20648 cmd.go:353] log is DEPRECATED and will be removed in a future version. Use logs instead.
Starting application
> blah#1.0.0 start /app
> node index.js
Example app listening on port 3000!
My guess is that you've got something going awry within your npm start execution, so I'd recommend fiddling with that aspect of your deployment and see if you can't resolve it that way.
Well as #heckj pointed out, it was a Docker issue on my kubernetes cluster. I updated the cluster from 1.6.13-gke.1 to v1.7.12-gke.0 and the pods worked fine again. I'm not sure what Docker version was used since there's another kubernetes bug that is preventing me from seeing it.
Problem description
I'm creating a docker container to run haskell binary. The binary in question is a website built with yesod. When the container starts up it looks promising but then fails with:
config/client_session_key.aes: openBinaryFile: does not exist (No such file or directory)
Steps to recreate
The Dockerfile for the binary is very basic. It looks like this:
FROM haskell:7.10.3
MAINTAINER Garry Cairns
ENV REFRESHED_AT 2015-09-05
RUN ["apt-get", "-y", "update"]
RUN ["apt-get", "-y", "install", "libpq-dev"]
I use docker-compose to link it to the database. The docker-compose file looks like this:
version: "2.0"
services:
database:
image: postgres
env_file: ./database/env
binary:
build: ./binary
command: /opt/server/api
env_file: ./api/env
links:
- database
tty: false
volumes:
- /etc/ssl/certs/:/etc/ssl/certs/
- ./binary:/opt/server/
The binary's volumes line is particularly important as it loads the binary into the container along with its static and config directories. I've checked they're definitely there and they are, so the container file structure ends up looking like this:
/opt/server
binary_file
/static
...
/config
client_session_key.aes
...
Connecting to the database seems to be working as I see some lines like this in the logging
binary_1 | Migrating: ALTER TABLE "blog" ALTER COLUMN "title" TYPE varchar(50)
before I see the error message.
Question
I suspect I either need to move the config folder to an alternative location where the binary file is expecting to find it, or set an environment variable somewhere in the yesod app before building it. I've been unable to find either the expected location or the correct environment variable to set thus far. Does anyone know what I'm missing?
The error message makes it look like it looks for config/client_session_key.aes at a relative path to the current working directory (CWD). Is it something as simple as specifying WORKDIR in the Dockerfile or working_dir in the compose YAML to /opt/server?
Information on WORKDIR for setting default CWD at image build time would be at https://docs.docker.com/engine/reference/builder/#workdir.
Information on setting Compose working_dir at runtime is at https://docs.docker.com/compose/compose-file/#cpu-shares-cpu-quota-cpuset-domainname-hostname-ipc-mac-address-mem-limit-memswap-limit-privileged-read-only-restart-stdin-open-tty-user-working-dir.