What I'm doing
I am using AWS batch to run a docker container for a large compute job. I have configured the ECR/ECS successfully to the best of my knowledge but am having issues running the required commands for reasons that are beyond my level of understanding with docker ( newbie )
What I need to do is pass the below commands into my application and start my application to perform some heavy computing tasks; all commands listed below must be present.
The Issue(s)
The issue arises when I send the submit job to AWS batch; this service pulls the image from the ACR ( amazon container repository ) and spins up a compute environment. The issue comes from when I try to run the command I pass in, below I will go throgh it.
"command": [
"mkdir -p logging",
"chmod 777 logging/",
"docker run -t -i -e my-application", # container name
"-e APIKEY",
"-e BASEURI",
"-e APIUSER",
"-v WORKSPACE /logging:/src/log",
"DOCKERIMAGE",
"python my_app.py",
"-t APP_USER",
"-e APP_ENVIRONMENT",
"-u APP_USERNAME",
"-p APP_PASSWORD",
"-i IN_PATH",
"-o OUT_PATH",
"-b tmp/"
]
The command above generates the following error(s)
container_linux.go:370: starting container process caused: exec: "mkdir -p log": executable file not found in $PATH
I tried to pass in the command to echo the env var $PATH but was unsuccesfull getting a response and resulted in a similar error.
I have ran successfully "ls" and was able to see the directory contents of my application inside.
I am not however able to run any of these commands that I have included in the command [] section. I have tried just running python and such in hopes of getting a more detailed error but was unsuccessful.
Logic in plain English
Create a path called logging if it doesnt exist
set the permissions for logging
run the docker container and pass in the environment variables while doing so
Tell docker to run the python file my_app.py and pass in the expected runtime args
Execute and perform the required logic deligated in the python3 application
Questions
Why can I not create a directory here called "logging" where am I ?
Am I running these properly as defined by AWS batch? or docker
What am I missing or where am I going wrong?
AWS Batch high level doc
AWS Batch link specific to what i'm doing
Assuming that you're following the syntax described in the Container
Properties
section of the AWS docs, you have several problems with the syntax of
your command directive.
First
The command directive can only run a single command. You can't mash together a bunch of commands as you're trying to do in your example. If you need to run multiple commands you would need to embed them as an argument to a shell. For example, something like:
command: ["/bin/sh", "-c", "mkdir -p logging; chmod 777 logging; ..."]
Second
You must properly tokenize your
command lines -- that is, when you type mkdir -p logging at the
command prompt, the shell splits this into three parts (or "tokens"): ['mkdir', '-p', 'logging']. You need to do the same thing when building up the
list of arguments to command.
This is invalid:
command: ["mkdir -p logging"]
That would looking for a command named mkdir -p logging, and of course no such command exists. That would properly be written as:
command: ["mkdir", "-p", "logging"]
Third
I'm not very familiar with the AWS batch environment, but it's unlikely you can run a docker command inside a docker` container as you're trying to do. It's unclear why you're doing this, though: why not just configure your AWS batch job with the appropriate image, environment variables, etc?
Take a look at some of these example job definitions.
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-compose file that contains a secret for my database.
port: 4466
managementApiSecret: ${DB_SECRET}
So I would like to use Docker-Compose's Variable Substitution (https://docs.docker.com/compose/compose-file/#variable-substitution) to be able to provide my secrets through an environment variable instead of my yaml file.
Is this at all possible using the "Application Settings" variables on my Azure Linux Docker Instance?
It doesn't seem to work for me, I've tried both ${VAR} and $VAR syntax and neither worked. I also tried with secrets that only contain alphanumerics and numbers.
Thanks in advance.
Frank
Environment variables that you need to start the container (for example: you want to include build number in container name) can be added to .env file in same directory as the docker-compose.yml file.
sample .env file:
DB_SECRET=foo
run: docker-compose config and verify that the variable has been substituted with the value you have in .env file
Also, I recommend using managementApiSecret:"${DB_SECRET}" (note the quotes around the variable) in your docker-compose.yml file
There might be azure specific way to share secrets but I didn't try that yet.
If you want to pass in environment variables that the container needs, then https://docs.docker.com/compose/compose-file/#env_file is what you want. Those environment vars will become part of environment inside docker container.
node.js application, built and deployed using docker-compose, doesn't see any custom set variables. console.log(process.env.VAR) logs undefined to console for any of those.
Variables are set using env_file property in yaml file. Only env_file property is used. There is an ENV value set in Dockerfile and it's accessible by the application.
docker exec -it <container-id> envdoes return all custom values. docker exec -it <container-id> sh returns only those set in base image - node-alpine (wiped out by exec?).
What can be wrong with the setup?
I've found that the issue is not with the compose file or wrong usage of env_file field.
The issue was with the env file itself. It used spaces when setting values. Like this: VAR = VAL instead of VAR=VAL.
While dotenv npm package allows this (I've used a sample that comes with a project as a base for deployment), docker and environment don't.
I've been experimenting with Docker recently on building some services to play around with and one thing that keeps nagging me has been putting passwords in a Dockerfile. I'm a developer so storing passwords in source feels like a punch in the face. Should this even be a concern? Are there any good conventions on how to handle passwords in Dockerfiles?
Definitely it is a concern. Dockerfiles are commonly checked in to repositories and shared with other people. An alternative is to provide any credentials (usernames, passwords, tokens, anything sensitive) as environment variables at runtime. This is possible via the -e argument (for individual vars on the CLI) or --env-file argument (for multiple variables in a file) to docker run. Read this for using environmental with docker-compose.
Using --env-file is definitely a safer option since this protects against the secrets showing up in ps or in logs if one uses set -x.
However, env vars are not particularly secure either. They are visible via docker inspect, and hence they are available to any user that can run docker commands. (Of course, any user that has access to docker on the host also has root anyway.)
My preferred pattern is to use a wrapper script as the ENTRYPOINT or CMD. The wrapper script can first import secrets from an outside location in to the container at run time, then execute the application, providing the secrets. The exact mechanics of this vary based on your run time environment. In AWS, you can use a combination of IAM roles, the Key Management Service, and S3 to store encrypted secrets in an S3 bucket. Something like HashiCorp Vault or credstash is another option.
AFAIK there is no optimal pattern for using sensitive data as part of the build process. In fact, I have an SO question on this topic. You can use docker-squash to remove layers from an image. But there's no native functionality in Docker for this purpose.
You may find shykes comments on config in containers useful.
Our team avoids putting credentials in repositories, so that means they're not allowed in Dockerfile. Our best practice within applications is to use creds from environment variables.
We solve for this using docker-compose.
Within docker-compose.yml, you can specify a file that contains the environment variables for the container:
env_file:
- .env
Make sure to add .env to .gitignore, then set the credentials within the .env file like:
SOME_USERNAME=myUser
SOME_PWD_VAR=myPwd
Store the .env file locally or in a secure location where the rest of the team can grab it.
See: https://docs.docker.com/compose/environment-variables/#/the-env-file
Docker now (version 1.13 or 17.06 and higher) has support for managing secret information. Here's an overview and more detailed documentation
Similar feature exists in kubernetes and DCOS
You should never add credentials to a container unless you're OK broadcasting the creds to whomever can download the image. In particular, doing and ADD creds and later RUN rm creds is not secure because the creds file remains in the final image in an intermediate filesystem layer. It's easy for anyone with access to the image to extract it.
The typical solution I've seen when you need creds to checkout dependencies and such is to use one container to build another. I.e., typically you have some build environment in your base container and you need to invoke that to build your app container. So the simple solution is to add your app source and then RUN the build commands. This is insecure if you need creds in that RUN. Instead what you do is put your source into a local directory, run (as in docker run) the container to perform the build step with the local source directory mounted as volume and the creds either injected or mounted as another volume. Once the build step is complete you build your final container by simply ADDing the local source directory which now contains the built artifacts.
I'm hoping Docker adds some features to simplify all this!
Update: looks like the method going forward will be to have nested builds. In short, the dockerfile would describe a first container that is used to build the run-time environment and then a second nested container build that can assemble all the pieces into the final container. This way the build-time stuff isn't in the second container. This of a Java app where you need the JDK for building the app but only the JRE for running it. There are a number of proposals being discussed, best to start from https://github.com/docker/docker/issues/7115 and follow some of the links for alternate proposals.
An alternative to using environment variables, which can get messy if you have a lot of them, is to use volumes to make a directory on the host accessible in the container.
If you put all your credentials as files in that folder, then the container can read the files and use them as it pleases.
For example:
$ echo "secret" > /root/configs/password.txt
$ docker run -v /root/configs:/cfg ...
In the Docker container:
# echo Password is `cat /cfg/password.txt`
Password is secret
Many programs can read their credentials from a separate file, so this way you can just point the program to one of the files.
run-time only solution
docker-compose also provides a non-swarm mode solution (since v1.11:
Secrets using bind mounts).
The secrets are mounted as files below /run/secrets/ by docker-compose. This solves the problem at run-time (running the container), but not at build-time (building the image), because /run/secrets/ is not mounted at build-time. Furthermore this behavior depends on running the container with docker-compose.
Example:
Dockerfile
FROM alpine
CMD cat /run/secrets/password
docker-compose.yml
version: '3.1'
services:
app:
build: .
secrets:
- password
secrets:
password:
file: password.txt
To build, execute:
docker-compose up -d
Further reading:
mikesir87's blog - Using Docker Secrets during Development
My approach seems to work, but is probably naive. Tell me why it is wrong.
ARGs set during docker build are exposed by the history subcommand, so no go there. However, when running a container, environment variables given in the run command are available to the container, but are not part of the image.
So, in the Dockerfile, do setup that does not involve secret data. Set a CMD of something like /root/finish.sh. In the run command, use environmental variables to send secret data into the container. finish.sh uses the variables essentially to finish build tasks.
To make managing the secret data easier, put it into a file that is loaded by docker run with the --env-file switch. Of course, keep the file secret. .gitignore and such.
For me, finish.sh runs a Python program. It checks to make sure it hasn't run before, then finishes the setup (e.g., copies the database name into Django's settings.py).
There is a new docker command for "secrets" management. But that only works for swarm clusters.
docker service create
--name my-iis
--publish target=8000,port=8000
--secret src=homepage,target="\inetpub\wwwroot\index.html"
microsoft/iis:nanoserver
The issue 13490 "Secrets: write-up best practices, do's and don'ts, roadmap" just got a new update in Sept. 2020, from Sebastiaan van Stijn:
Build time secrets are now possible when using buildkit as builder; see the blog post "Build secrets and SSH forwarding in Docker 18.09", Nov. 2018, from Tõnis Tiigi.
The documentation is updated: "Build images with BuildKit"
The RUN --mount option used for secrets will graduate to the default (stable) Dockerfile syntax soon.
That last part is new (Sept. 2020)
New Docker Build secret information
The new --secret flag for docker build allows the user to pass secret information to be used in the Dockerfile for building docker images in a safe way that will not end up stored in the final image.
id is the identifier to pass into the docker build --secret.
This identifier is associated with the RUN --mount identifier to use in the Dockerfile.
Docker does not use the filename of where the secret is kept outside of the Dockerfile, since this may be sensitive information.
dst renames the secret file to a specific file in the Dockerfile RUN command to use.
For example, with a secret piece of information stored in a text file:
$ echo 'WARMACHINEROX' > mysecret.txt
And with a Dockerfile that specifies use of a BuildKit frontend docker/dockerfile:1.0-experimental, the secret can be accessed.
For example:
# syntax = docker/dockerfile:1.0-experimental
FROM alpine
# shows secret from default secret location:
RUN --mount=type=secret,id=mysecret cat /run/secrets/mysecret
# shows secret from custom secret location:
RUN --mount=type=secret,id=mysecret,dst=/foobar cat /foobar
This Dockerfile is only to demonstrate that the secret can be accessed. As you can see the secret printed in the build output. The final image built will not have the secret file:
$ docker build --no-cache --progress=plain --secret id=mysecret,src=mysecret.txt .
...
#8 [2/3] RUN --mount=type=secret,id=mysecret cat /run/secrets/mysecret
#8 digest: sha256:5d8cbaeb66183993700828632bfbde246cae8feded11aad40e524f54ce7438d6
#8 name: "[2/3] RUN --mount=type=secret,id=mysecret cat /run/secrets/mysecret"
#8 started: 2018-08-31 21:03:30.703550864 +0000 UTC
#8 1.081 WARMACHINEROX
#8 completed: 2018-08-31 21:03:32.051053831 +0000 UTC
#8 duration: 1.347502967s
#9 [3/3] RUN --mount=type=secret,id=mysecret,dst=/foobar cat /foobar
#9 digest: sha256:6c7ebda4599ec6acb40358017e51ccb4c5471dc434573b9b7188143757459efa
#9 name: "[3/3] RUN --mount=type=secret,id=mysecret,dst=/foobar cat /foobar"
#9 started: 2018-08-31 21:03:32.052880985 +0000 UTC
#9 1.216 WARMACHINEROX
#9 completed: 2018-08-31 21:03:33.523282118 +0000 UTC
#9 duration: 1.470401133s
...
The 12-Factor app methodology tells, that any configuration should be stored in environment variables.
Docker compose could do variable substitution in configuration, so that could be used to pass passwords from host to docker.
Starting from Version 20.10, besides using secret-file, you could also provide secrets directly with env.
buildkit: secrets: allow providing secrets with env moby/moby#41234 docker/cli#2656 moby/buildkit#1534
Support --secret id=foo,env=MY_ENV as an alternative for storing a secret value to a file.
--secret id=GIT_AUTH_TOKEN will load env if it exists and the file does not.
secret-file:
THIS IS SECRET
Dockerfile:
# syntax = docker/dockerfile:1.3
FROM python:3.8-slim-buster
COPY build-script.sh .
RUN --mount=type=secret,id=mysecret ./build-script.sh
build-script.sh:
cat /run/secrets/mysecret
Execution:
$ export MYSECRET=theverysecretpassword
$ export DOCKER_BUILDKIT=1
$ docker build --progress=plain --secret id=mysecret,env=MYSECRET -t abc:1 . --no-cache
......
#9 [stage-0 3/3] RUN --mount=type=secret,id=mysecret ./build-script.sh
#9 sha256:e32137e3eeb0fe2e4b515862f4cd6df4b73019567ae0f49eb5896a10e3f7c94e
#9 0.931 theverysecretpassword#9 DONE 1.5s
......
With Docker v1.9 you can use the ARG instruction to fetch arguments passed by command line to the image on build action. Simply use the --build-arg flag. So you can avoid to keep explicit password (or other sensible information) on the Dockerfile and pass them on the fly.
source: https://docs.docker.com/engine/reference/commandline/build/ http://docs.docker.com/engine/reference/builder/#arg
Example:
Dockerfile
FROM busybox
ARG user
RUN echo "user is $user"
build image command
docker build --build-arg user=capuccino -t test_arguments -f path/to/dockerfile .
during the build it print
$ docker build --build-arg user=capuccino -t test_arguments -f ./test_args.Dockerfile .
Sending build context to Docker daemon 2.048 kB
Step 1 : FROM busybox
---> c51f86c28340
Step 2 : ARG user
---> Running in 43a4aa0e421d
---> f0359070fc8f
Removing intermediate container 43a4aa0e421d
Step 3 : RUN echo "user is $user"
---> Running in 4360fb10d46a
**user is capuccino**
---> 1408147c1cb9
Removing intermediate container 4360fb10d46a
Successfully built 1408147c1cb9
Hope it helps! Bye.
Something simply like this will work I guess if it is bash shell.
read -sp "db_password:" password | docker run -itd --name <container_name> --build-arg mysql_db_password=$db_password alpine /bin/bash
Simply read it silently and pass as argument in Docker image. You need to accept the variable as ARG in Dockerfile.
While I totally agree there is no simple solution. There continues to be a single point of failure. Either the dockerfile, etcd, and so on. Apcera has a plan that looks like sidekick - dual authentication. In other words two container cannot talk unless there is a Apcera configuration rule. In their demo the uid/pwd was in the clear and could not be reused until the admin configured the linkage. For this to work, however, it probably meant patching Docker or at least the network plugin (if there is such a thing).