https://github.com/arne-cl/docker-nginx-env-example
How to use env variables in ngxinx inside docker-compose.
https://github.com/arne-cl/docker-nginx-env-example
Last synced: 4 months ago
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How to use env variables in ngxinx inside docker-compose.
- Host: GitHub
- URL: https://github.com/arne-cl/docker-nginx-env-example
- Owner: arne-cl
- Created: 2020-08-04T21:04:35.000Z (almost 5 years ago)
- Default Branch: master
- Last Pushed: 2020-08-04T21:07:37.000Z (almost 5 years ago)
- Last Synced: 2025-01-06T09:12:24.750Z (6 months ago)
- Language: Dockerfile
- Size: 2.93 KB
- Stars: 0
- Watchers: 2
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
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README
# docker-compose-nginx-env-example
This repo demonstrates how to use an environment variable in `nginx`,
when you run `nginx` inside a Docker container with `docker-compose`.
In this example, `docker-compose` passes the `HOST` env to the `Dockerfile`
to build the container using:
```
build:
args:
- HOST
```
To make the `HOST` env variable available at run-time, `docker-compose` uses:
```
environment:
- HOST
```
In both cases, the `HOST` env is picked up by the `Dockerfile` using:
```
ARG HOST
```
The `Dockerfile` also overwrites the default `nginx` config file with our own:
```
ADD nginx.conf /etc/nginx/nginx.conf
```
By default, `nginx` doesn't allow env variables to be used, so we have to
make this explicit in `nginx.conf`:
```
env HOST;
```
For some reason, we can't use the env variable directly, but need to extract it
using one of the supported scripting languages (here: Perl):
```
load_module modules/ngx_http_perl_module.so;
perl_set $ext_hostname 'sub { return $ENV{"HOST"}; }';
```
This will make the `HOST` env available inside `nginx` as `$ext_hostname`,
e.g. with a directive like:
```
server {
listen 80;
location / {
return 200 'HOST at run-time: ${ext_hostname}\n';
}
}
```
# Usage examples
## docker build
To make the env variable `HOST` available at built-time, use:
```
$ docker build --build-arg HOST=example.com -t docker-nginx-env .
[...]
Step 6/6 : RUN echo "HOST at build-time: $HOST"
---> Running in ebb80aff9255
HOST at build-time: example.com
[...]
```
## docker run
The `HOST` env variable used at build-time is **not available** at run-time, though:
```
$ docker run -p 80:80 -d docker-nginx-env
5ce21faf4cebb35383af19171a4359c1449b1dff92c0552ef75143d24021ef22
$ curl localhost
HOST at run-time:
```
If you want to set the `HOST` env variable inside `nginx` at Docker run-time, do this:
```
$ docker run -p 80:80 -d --env HOST=foo docker-nginx-env
710b70aef5edfd5b5ccc13e954f57e1d407a2156adea7b989d55678a247503be
$ curl localhost
HOST at run-time: foo
```
## docker-compose
With `docker-compose`, the `HOST` env is set like this:
```
$ HOST=foo docker-compose -f docker-compose.yml up --build --force-recreate
[...]
Step 6/6 : RUN echo "HOST at build-time: $HOST"
---> Running in d1f9023e2797
HOST at build-time: foo
```
This command will both build and run the container, so calling `nginx` works as expected:
$ curl localhost
HOST at run-time: foo