Many improvements:

Handle common errors with better messages
Add docker-compose example
Flesh out docs
Make multi-arch dockerfile work

.dockerignore

@@ -0,0 +1 @@
+target

Cargo.toml

@@ -2,6 +2,9 @@
 name = "docker-vhoster"
 version = "0.1.0"
 edition = "2021"
+[[bin]]
+name = "docker-vhoster"
+path = "src/main.rs"
 
 # [package.release]
 # opt-level = 's'  # Optimize for size.
@@ -10,11 +13,13 @@ edition = "2021"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+anyhow = "1.0"
 bollard = "0.11"
-envy = "0.4"
+# envy = "0.4"
 serde = { version = "1.0", features = ["derive"] }
 tokio = { version = "1", features = ["full"] }
 chrono = "0.4"
 futures-util = "0.3"
 futures-retry = "0.6.0"
-ctrlc = { version = "3.0", features = ["termination"] }
+ctrlc = { version = "3.0", features = ["termination"] }
+clap = { version = "3.1", features = ["derive", "env", "color"] }

Dockerfile

@@ -1,23 +1,30 @@
 FROM rust:1.59 as BUILD
 
 ARG RUSTFLAGS='-C link-arg=-s'
-ARG TARGET='x86_64-unknown-linux-musl'
+ARG TARGETPLATFORM
+RUN case "$TARGETPLATFORM" in \
+  "linux/amd64") echo x86_64-unknown-linux-musl > /rust_target.txt ;; \
+  "linux/arm64") echo aarch64-unknown-linux-musl > /rust_target.txt ;; \
+  *) exit 1 ;; \
+esac
 
-RUN USER=root cargo new --bin docker-vhoster
-WORKDIR /docker-vhoster
+RUN mkdir /build && cd /build &&\
+  USER=root cargo new --bin docker-vhoster &&\
+  cargo install cargo-build-deps &&\
+  rustup target add $(cat /rust_target.txt)
+WORKDIR /build/docker-vhoster
 
 # copy over your manifests
-COPY ./Cargo.toml ./Cargo.toml
+COPY ./Cargo.toml ./Cargo.lock ./
 
 ENV RUSTFLAGS=${RUSTFLAGS}
 # cache deps
-RUN rustup target add ${TARGET} && cargo build --release --target ${TARGET} && rm src/*.rs
-COPY ./src /docker-vhoster/src
+RUN cargo build-deps --release --target=$(cat /rust_target.txt)
+COPY ./src /build/docker-vhoster/src
 # build as a statically linked library
-RUN cargo build --release --target ${TARGET} --bin docker-vhoster
-#RUN ls -alh /docker-vhoster/target/${TARGET} && exit 1  
+RUN cargo build --release --target $(cat /rust_target.txt) --bin docker-vhoster &&\
+  mv /build/docker-vhoster/target/$(cat /rust_target.txt)/release/docker-vhoster /
 
 FROM scratch
-ARG TARGET='x86_64-unknown-linux-musl'
-COPY --from=BUILD /docker-vhoster/target/${TARGET}/release/docker-vhoster /
+COPY --from=BUILD /docker-vhoster /
 CMD ["/docker-vhoster"]

Makefile

@@ -0,0 +1,3 @@
+
+build:
+	docker buildx build --platform linux/arm64,linux/amd64 -t itaylor/docker-vhoster --push ./

Readme.md

@@ -2,18 +2,57 @@
 
 Listens on the docker socket for containers to start/end and adds entries for them to your `/etc/hosts` file.
 
-This is designed to be used alongside a tool like `jwilder/nginx-proxy` which creates vhost entries for running services.  It allows you to map them to the hosts file.
+This is designed to be used alongside a tool like `jwilder/nginx-proxy` which creates vhost entries for running services.  
+If you follow it's pattern for setting `VIRTUAL_HOST` environment variables that program nginx, this will allow those same variables to also control your `/etc/hosts` file.
 
-## Configuration
+## One time setup:
 
-Three options:
-* `HOST_FILE_LOCATION`: default: `/etc/hosts` the path to the etc hosts file to modify.
-* `ENV_VAR_NAME`: default: `VIRTUAL_HOST` the name of the environment variable to look at to determine what vhosts to add.
-* `VHOST_IP_ADDR` default `127.0.0.1` Use this to provide/override the IP address used to map the vhost entries.
+We need to give your user permission to modify the /etc/hosts file.  This is done differently on different OS.
 
-When run as a container, pass these as env vars.  When run as a cli program, they are arguments.
+On MacOS, run in terminal:
+```sh
+chmod +a user:$(whoami) allow read,write,append,readattr,writeattr,readextattr,writeextattr,readsecurity /etc/hosts
+```
 
+On Windows... Powershell is too complex for me to understand how to do it as a script, so in the UI:
+* Navigate in Explorer to `C:\Windows\System32\drivers\etc`
+* Right click the `hosts` file -> Properties
+* Security -> Edit 
+* Add...
+* Enter your user name 
+* Check Names 
+* Ok
+* Check "Full Control" box
+* Ok, Ok
+
+On Linux: 
+Do nothing, this just works
+
+## Options
+
+Options:
+All options can be set as cli arguments or as env vars
+
+| argument                           | env var              | default       | description |
+| ---------------------------------- | -------------------- | ------------- | ----------- |
+| `-h, --host-file-location <path>`  | `HOST_FILE_LOCATION` | `/etc/hosts`  | The path to the hosts file to modify |
+| `-e, --env-var-name <string>`      | `ENV_VAR_NAME`       | `VIRTUAL_HOST`| The env var used to look up the host name on a per-container basis | 
+| `-v, --vhost-ip-addr <ip address>` | `VHOST_IP_ADDR`      | `127.0.0.1`   | The IP address to set in the /etc/hosts file |
+
+## Required file/volume mount!
 You must use this on a machine/container where `/var/run/docker.sock` is available
 
+## Running it
+The most common way this is meant to be used is to run inside of docker alongside containers.
 Typically, if you're running `docker-vhoster` inside of docker, this is done as:
-`docker run -v /var/run/docker.sock:/var/run/docker.sock:ro itaylor/docker-vhoster`
+`docker run -v /var/run/docker.sock:/var/run/docker.sock:ro -v /etc/hosts:/tmp/hosts itaylor/docker-vhoster -h /tmp/hosts`
+
+## Example using docker-compose
+See the `example/` folder.
+```sh
+cd example/
+docker-compose up
+```
+Once the containers start you'll be able to open a browser to `http://web-example.fake.com` and have it display a hello world message.
+
+*Note* if using Docker for windows, you'll have to change the `example/docker-compose.yml` to have the correct path to Windows' `etc/hosts` file.

example/docker-compose.yml

@@ -0,0 +1,32 @@
+# An example docker-compose config that uses jwilder/nginx-proxy and itaylor/docker-vhoster to automatically add /etc/hosts entries
+services: 
+
+  nginx-proxy:
+    image: jwilder/nginx-proxy
+    ports:
+      - 80:80
+      - 443:443
+    volumes:
+      - "/var/run/docker.sock:/tmp/docker.sock:ro"
+
+  docker-vhoster:
+    build: ../
+    volumes:
+      - "/var/run/docker.sock:/var/run/docker.sock:ro"
+      - "/etc/hosts:/tmp/hosts"
+    #  For windows, use below instead: 
+    #  - C:\Windows\System32\drivers\etc\hosts:/tmp/hosts      
+    environment:
+      - HOST_FILE_LOCATION=/tmp/hosts
+
+  web-example:
+    image: node:16
+    volumes:
+      - "./helloworld.js:/app/helloworld.js"
+    command: node /app/helloworld.js
+    expose:
+      - 3000
+    environment:
+      # The values set here will be used by both nginx-proxy to setup nginx
+      # And by docker-vhoster to edit the /etc/hosts entries
+      - VIRTUAL_HOST=web-example.fake.com,web-example.local

example/helloworld.js

@@ -0,0 +1,12 @@
+const http = require("http");
+const { chdir } = require("process");
+const host = '0.0.0.0';
+const port = 3000;
+const server = http.createServer(onRequest);
+server.listen(port, host, () => {
+  console.log(`Running on http://${host}:${port}`);
+});
+function onRequest(req,res) {
+  res.writeHead(200);
+  res.end("Hello World!");
+}