I want to compose two environment variables: first define a "root" and in the same line use that to create a composed one. In example, filename and append extension.
Doing this container,
FROM centos:7
ENV ROOT_VAR=stringy ROOT_VAR_TGZ=${ROOT_VAR}.tar.gz
RUN echo ${ROOT_VAR} $ ${ROOT_VAR_TGZ}
The output for echo is
stringy $ .tar.gz
But when splitting each variable in an individual ENV command is composed correctly.
Is this the expected behaviour?
The behaviour is clearly explained in the docker reference document:
Environment variable substitution will use the same value for each variable throughout the entire instruction. In other words, in this example:
ENV abc=hello
ENV abc=bye def=$abc
ENV ghi=$abc
will result in def having a value of hello, not bye. However, ghi will have a value of bye because it is not part of the same instruction that set abc to bye.
Related
I am using a base.env as an env_file for several of my docker services.In this base.env I have several parts of the environment variable that repeat throughout the file. For example, port and ip are the same for three different environment variables.
I would like to specify these in an environment variable and reuse those variables to fill out the other environment variables.
Here is base.env:
### Kafka
# kafka's port is 9092 by default in the docker-compose file
KAFKA_PORT_NUMBER=9092
KAFKA_TOPIC=some-topic
KAFKA_IP=kafka
KAFKA_CONN: //$KAFKA_IP:$KAFKA_PORT_NUMBER/$KAFKA_TOPIC
# kafka topic that is to be created. Note that ':1:3' should remain the same.
KAFKA_CREATE_TOPICS=$KAFKA_TOPIC:1:3
# the url for connecting to kafka
KAFKA_ADVERTISED_LISTENERS=PLAINTEXT://$KAFKA_IP:$KAFKA_PORT_NUMBER
I have tried writing
KAFKA_CONN: //$${KAFKA_IP}:$${KAFKA_PORT_NUMBER}/$${KAFKA_TOPIC}
in the environment section of the appropriate service in the docker-compose.yml, but this gets interpreted as a literal string in the container.
Is there a way to do what I want in the base.env file?
Thank you for your help!
You can actually do it like this (at least in vlucas/dotenv package (php), not sure about others, please check it yourself)
MAIL_NAME=${MAIL_FROM}
Read more about it here
There is no way to do this in an env_file since it is not run as a bash command. This means that the variable is not created and then concatenated into the next variable it appears in. The values are just read in as they are in the env_file.
I used $ in Node.js and React.js , and both worked
POSTGRES_PORT=5432
DATABASE_URL="postgresql://root#localhost:${POSTGRES_PORT}/dbname"
and in react
REACT_APP_DOMAIN=domain.com
#API Configurations
REACT_APP_API_DOMAIN=$REACT_APP_DOMAIN
I know that I am a little late to the party, but I had the same question and I found a way to do it. There is a package called env-cmd, which allows you to use a .js file as an .env file. The file simply needs to export an object with the keys being your environment variable names and the values being, well, the values. This now allows you to run javascript before the environment variables are exported and thus use environment variables to set others.
I temporarly managed to deal with this where I create a script to replace env file vars from another env file vars like so:
.env.baseurl:
BASEURL1=http://127.0.0.1
BASEURL2=http://192.168.1.10
.env.uris.default:
URI1=${BASEURL1}/uri1
URI2=${BASEURL2}/uri2
URI3=${BASEURL2}/uri3
convert-env.sh:
#!/bin/bash
# To allow using sed correctly from same file multiple times
cp ./.env.uris.default ./.env.uris
# Go through each variable in .env.baseurl and store them as key value
for VAR in $(cat ./.env.baseurl); do
key=$(echo $VAR | cut -d "=" -f1)
value=$(echo $VAR | cut -d "=" -f2)
# Replace env vars by values in ./.env.uris
sed -i "s/\${$key}/$value/g" ./.env.uris
done
then you can run docker run command to start the container and load it with your env vars (from .env.baseurl to .env.uris) :
docker run -d --env-file "./.env.uris" <image>
This is not the best solution but helped me for now.
Using Nextjs, in the .env.local file I have the following variables:
NEXT_PUBLIC_BASE_URL = http://localhost:5000
NEXT_PUBLIC_API_USERS_URL_REGISTER = ${NEXT_PUBLIC_BASE_URL}/api/users/register
it works well, I used the variable NEXT_PUBLIC_BASE_URL in the variable NEXT_PUBLIC_API_USERS_URL_REGISTER.
There is a simple way to do this you will just need to run:
env >>/root/.bashrc && source /root/.bashrc
this will append all environment variables inside /root/.bashrc then convert those if they have not been converted while passing the env-file
you can use something like this ${yourVar}
KAFKA_ADVERTISED_LISTENERS=PLAINTEXT://${KAFKA_IP}:${$KAFKA_PORT_NUMBER}
I test this on PHP / Laravel .env it's working fine
Docker env files look similar to shell scripts defining variables.
Unfortunately in env files, values cannot be quoted and so simply sourcing them only works if there are no "special" characters in the values.
VAR1=This_works
VAR2=This will not work
VAR3=This won't either
Is there any way you can use these files in a shell script?
My current approach is this:
eval $( perl -ne '
s/\x27/\x27\\\x27\x27/g;
s/^(\w+)=(.+)$/export $1=\x27$2\x27/ and print
' "path/to/env_file" )
So I'm searching for any quote in each line of the env file and replace it by '\''.
Then I'm modifying each line which starts with an identifier (\w+) followed by a = and any text (.+). So the VAR3 will become: export VAR3='This won'\''t either.
The modified line is then printed.
Everything which was printed is eval-ed and so the variables will be available in my shell's environment.
Are there other proposals how to achieve this?
Can I do character substitution to set one ENV value based on another one?
My scenario...
ENV tableauVersion 2019-4-0
ENV tableauVersionDots 2019.4.0
ENV tabcmdURL https://downloads.tableau.com/esdalt/${tableauVersionDots}/tableau-tabcmd-${tableauVersion}_all.deb
Obviously, i'd like to be able to define tableauVersionDots based on the tableauVersion ENV variable (i.e. replace - with .)
No. The only substitutions it's possible to do in Dockerfile ENV statements are the ones shown in the Dockerfile documentation: $variable, ${variable}, ${variable:-default}, or ${variable:+yes it is set}.
For URLs like that you don't really need them in an environment variable. If you do need to compute it and then fetch it you could do it within a single RUN statement
RUN tableauVersionDots=$(echo "$tableauVersion" | sed 's/-/./g') \
&& curl -LO https://downloads.tableau.com/esdalt/${tableauVersionDots}/tableau-tabcmd-${tableauVersion}_all.deb
The variable setting won't survive beyond this RUN statement (and in shell space I haven't even bothered to export it) but that's probably okay just for fetching a URL.
I am using a base.env as an env_file for several of my docker services.In this base.env I have several parts of the environment variable that repeat throughout the file. For example, port and ip are the same for three different environment variables.
I would like to specify these in an environment variable and reuse those variables to fill out the other environment variables.
Here is base.env:
### Kafka
# kafka's port is 9092 by default in the docker-compose file
KAFKA_PORT_NUMBER=9092
KAFKA_TOPIC=some-topic
KAFKA_IP=kafka
KAFKA_CONN: //$KAFKA_IP:$KAFKA_PORT_NUMBER/$KAFKA_TOPIC
# kafka topic that is to be created. Note that ':1:3' should remain the same.
KAFKA_CREATE_TOPICS=$KAFKA_TOPIC:1:3
# the url for connecting to kafka
KAFKA_ADVERTISED_LISTENERS=PLAINTEXT://$KAFKA_IP:$KAFKA_PORT_NUMBER
I have tried writing
KAFKA_CONN: //$${KAFKA_IP}:$${KAFKA_PORT_NUMBER}/$${KAFKA_TOPIC}
in the environment section of the appropriate service in the docker-compose.yml, but this gets interpreted as a literal string in the container.
Is there a way to do what I want in the base.env file?
Thank you for your help!
You can actually do it like this (at least in vlucas/dotenv package (php), not sure about others, please check it yourself)
MAIL_NAME=${MAIL_FROM}
Read more about it here
There is no way to do this in an env_file since it is not run as a bash command. This means that the variable is not created and then concatenated into the next variable it appears in. The values are just read in as they are in the env_file.
I used $ in Node.js and React.js , and both worked
POSTGRES_PORT=5432
DATABASE_URL="postgresql://root#localhost:${POSTGRES_PORT}/dbname"
and in react
REACT_APP_DOMAIN=domain.com
#API Configurations
REACT_APP_API_DOMAIN=$REACT_APP_DOMAIN
I know that I am a little late to the party, but I had the same question and I found a way to do it. There is a package called env-cmd, which allows you to use a .js file as an .env file. The file simply needs to export an object with the keys being your environment variable names and the values being, well, the values. This now allows you to run javascript before the environment variables are exported and thus use environment variables to set others.
I temporarly managed to deal with this where I create a script to replace env file vars from another env file vars like so:
.env.baseurl:
BASEURL1=http://127.0.0.1
BASEURL2=http://192.168.1.10
.env.uris.default:
URI1=${BASEURL1}/uri1
URI2=${BASEURL2}/uri2
URI3=${BASEURL2}/uri3
convert-env.sh:
#!/bin/bash
# To allow using sed correctly from same file multiple times
cp ./.env.uris.default ./.env.uris
# Go through each variable in .env.baseurl and store them as key value
for VAR in $(cat ./.env.baseurl); do
key=$(echo $VAR | cut -d "=" -f1)
value=$(echo $VAR | cut -d "=" -f2)
# Replace env vars by values in ./.env.uris
sed -i "s/\${$key}/$value/g" ./.env.uris
done
then you can run docker run command to start the container and load it with your env vars (from .env.baseurl to .env.uris) :
docker run -d --env-file "./.env.uris" <image>
This is not the best solution but helped me for now.
Using Nextjs, in the .env.local file I have the following variables:
NEXT_PUBLIC_BASE_URL = http://localhost:5000
NEXT_PUBLIC_API_USERS_URL_REGISTER = ${NEXT_PUBLIC_BASE_URL}/api/users/register
it works well, I used the variable NEXT_PUBLIC_BASE_URL in the variable NEXT_PUBLIC_API_USERS_URL_REGISTER.
There is a simple way to do this you will just need to run:
env >>/root/.bashrc && source /root/.bashrc
this will append all environment variables inside /root/.bashrc then convert those if they have not been converted while passing the env-file
you can use something like this ${yourVar}
KAFKA_ADVERTISED_LISTENERS=PLAINTEXT://${KAFKA_IP}:${$KAFKA_PORT_NUMBER}
I test this on PHP / Laravel .env it's working fine
As part of a Dockerfile, I am attempting to modify a text file (ssh_config) to contain a variable passed through by the user (as an ARG) to the docker container at build time.
In my Dockerfile I have (this is not the entire file):
ARG key_name
RUN echo 'Host geoserver\n\
User user\n\
HostName 38.191.191.111\n\
IdentityFile /root/$key_name' >> /etc/ssh/ssh_config
This collects the argument key_name, and then appends some text to the ssh_config text file.
This is run as follows:
docker build --build-arg key_name=GC -t pyramid .
When I check to see what has been written, the key_name variable hasn't been parsed, and instead has been written as text (so literally as $key_name). Obviously I want it to be replaced with the variable passed through ARG.
I have tried using ${key_file} instead of just $key_file, I just get the same text in the text file but with curly braces included.
So my question is, how can I use the ARG variable correctly within the RUN echo statement?
First: Make sure, your ARG comes after your FROM. See: https://docs.docker.com/engine/reference/builder/#understand-how-arg-and-from-interact
Second: As you can see here, variables won't be interpretad inside '', so use "" instead.
When you surround the variable with single quotes it doesn't get replaced.
If you need the single qoutes in the file just surround everything with double quotes, otherwise just remove the single quotes all together.
ARG key_name
RUN echo "'Host geoserver\n\
User user\n\
HostName 38.191.191.111\n\
IdentityFile /root/$key_name'" >> /etc/ssh/ssh_config