nginx: use environment variables
The correct usage would be $SOME_IP_from_env
, but environment variables set from nginx.conf cannot be used in server, location or http blocks.
You can use environment variables if you use the openresty bundle, which includes Lua.
You can access the variables via modules - I found options for doing it with Lua and Perl.
Wrote about it on my company's blog:
https://web.archive.org/web/20170712003702/https://docs.apitools.com/blog/2014/07/02/using-environment-variables-in-nginx-conf.html
The TL;DR:
env API_KEY;
And then:
http {
...
server {
location / {
# set var using Lua
set_by_lua $api_key 'return os.getenv("API_KEY")';
# set var using perl
perl_set $api_key 'sub { return $ENV{"API_KEY"}; }';
...
}
}
}
EDIT: original blog is dead, changed link to wayback machine cache
With NGINX Docker image
Apply envsubst
on template of the configuration file at container start. envsubst
is included in official NGINX docker images.
Environment variable is referenced in a form $VARIABLE
or ${VARIABLE}
.
nginx.conf.template:
user nginx;
worker_processes 1;
error_log /var/log/nginx/error.log warn;
pid /var/run/nginx.pid;
events {
worker_connections 1024;
}
http {
server {
listen 80;
location / {
access_log off;
return 200 '${MESSAGE}';
add_header Content-Type text/plain;
}
}
}
Dockerfile:
FROM nginx:1.17.8-alpine
COPY ./nginx.conf.template /nginx.conf.template
CMD ["/bin/sh" , "-c" , "envsubst < /nginx.conf.template > /etc/nginx/nginx.conf && exec nginx -g 'daemon off;'"]
Build and run docker:
docker build -t foo .
docker run --rm -it --name foo -p 8080:80 -e MESSAGE="Hellou World" foo
NOTE:If config template contains dollar sign $
which should not be substituted then list all used variables as parameter of envsubst
so that only those are replaced. E.g.:
CMD ["/bin/sh" , "-c" , "envsubst '$USER_NAME $PASSWORD $KEY' < /nginx.conf.template > /etc/nginx/nginx.conf && exec nginx -g 'daemon off;'"]
Nginx Docker documentation for reference. Look for Using environment variables in nginx configuration.
Using environment variables in nginx configuration
Out-of-the-box, nginx doesn’t support environment variables inside most configuration blocks. But envsubst may be used as a workaround if you need to generate your nginx configuration dynamically before nginx starts.
Here is an example using docker-compose.yml:
web: image: nginx volumes: - ./mysite.template:/etc/nginx/conf.d/mysite.template ports: - "8080:80" environment: - NGINX_HOST=foobar.com - NGINX_PORT=80 command: /bin/bash -c "envsubst < /etc/nginx/conf.d/mysite.template > /etc/nginx/conf.d/default.conf && exec nginx -g 'daemon off;'"
The
mysite.template
file may then contain variable references like this:
listen ${NGINX_PORT}
;