fix: add hello-haproxy

.github/workflows/ci.yml

@@ -40,3 +40,26 @@ jobs:
         with:
           lua-version: ${{ matrix.version }}
           rockspec: ${{ matrix.package }}
+
+
+  hello-haproxy:
+    runs-on: ubuntu-latest
+    env:
+      LD_SDK_KEY: "foo"
+    steps:
+      - uses: actions/checkout@v4
+      - name: Build hello-haproxy image
+        run: |
+          docker build -t launchdarkly:hello-haproxy -f ./examples/hello-haproxy/Dockerfile .
+      - name: Run hello-haproxy container in background
+        # The sleep is to give haproxy some time to start-up.
+        run: |
+          docker run -dit --rm --name hello-haproxy -p 8123:8123 --env LD_SDK_KEY="$LD_SDK_KEY" launchdarkly:hello-haproxy
+          sleep 5
+      - name: Evaluate feature flag
+        run: |
+          curl -s -v http://localhost:8123 | tee response.txt
+          grep -F "Feature flag is false for this user" response.txt || (echo "Expected false evaluation!" && exit 1)
+      - name: Stop hello-haproxy container
+        run: |
+          docker stop hello-haproxy

README.md

@@ -49,6 +49,14 @@ Getting started
 Refer to the [SDK documentation](https://docs.launchdarkly.com/sdk/server-side/lua#getting-started) for instructions on 
 getting started with using the SDK.
 
+Runnable examples in this repo are available:
+
+| Example                                         | Purpose                                                                                       |
+|-------------------------------------------------|-----------------------------------------------------------------------------------------------|
+| [hello-lua-server](./examples/hello-lua-server) | Demonstrates basic example of Lua SDK usage from the command line.                            |
+| [hello-haproxy](./examples/hello-haproxy)       | Demonstrates usage of the Lua SDK as a [HAproxy](https://www.haproxy.org/) module via Docker. |
+
+
 There are two paths to installing the SDK. In both cases, you must first install the native 
 [LaunchDarkly C++ Server-side SDK](https://github.com/launchdarkly/cpp-sdks).
 

examples/hello-haproxy/Dockerfile

@@ -0,0 +1,41 @@
+FROM ubuntu:22.04
+
+RUN apt-get update && apt-get install -y \
+    curl luarocks lua5.3 lua5.3-dev \
+    haproxy apt-transport-https ca-certificates \
+    software-properties-common
+
+RUN add-apt-repository ppa:mhier/libboost-latest && \
+     apt-get update && \
+     apt-get install -y boost1.81
+
+RUN curl https://github.com/launchdarkly/cpp-sdks/releases/download/launchdarkly-cpp-server-v3.3.1/linux-gcc-x64-dynamic.zip -L -o /tmp/sdk.zip && \
+    mkdir ./cpp-sdk && \
+    unzip /tmp/sdk.zip -d ./cpp-sdk && \
+    rm /tmp/sdk.zip
+
+COPY . .
+
+RUN luarocks make launchdarkly-server-sdk-2.0.2-0.rockspec LD_DIR=./cpp-sdk/build-dynamic/release
+
+COPY ./examples/hello-haproxy/haproxy.cfg /etc/haproxy/haproxy.cfg
+COPY ./examples/hello-haproxy/service.lua /service.lua
+
+# The strategy for this Docker example is to download the C++ SDK release artifacts and use those instead of compiling
+# from source. This is for example/CI purposes only; generally it's better to build from source to ensure all libraries
+# are compatible.
+#
+# Since we require a newer version of boost than is available in Ubuntu 22.04, we grab it from a PPA (mhier/libboost-latest).
+#
+# The SDK dynamic libs expect the boost libs to follow a specific naming convention, which isn't what
+# the libraries from the PPA follow ('-mt' suffix is added to indicate the libraries are built with multithreading support enabled.)
+#
+# It's not 100% clear if these libraries are multithread enabled (build logs in the PPA seem to indicate it),
+# but even so, the C++ SDK is single-threaded.
+#
+# To workaround, add symlinks with the expected names.
+RUN cd /usr/lib/x86_64-linux-gnu && \
+    ln -s libboost_json.so.1.81.0 libboost_json-mt-x64.so.1.81.0 && \
+    ln -s libboost_url.so.1.81.0 libboost_url-mt-x64.so.1.81.0
+
+CMD  haproxy -d -f /etc/haproxy/haproxy.cfg

examples/hello-haproxy/README.md

@@ -0,0 +1,16 @@
+# LaunchDarkly Lua server-side SDK HAProxy example
+
+We've built a minimal dockerized example of using the Lua SDK with [HAProxy](https://www.haproxy.org/). For more comprehensive instructions, you can visit the [Using the Lua SDK with HAProxy guide](https://docs.launchdarkly.com/guides/sdk/haproxy) or the [Lua reference guide](https://docs.launchdarkly.com/sdk/server-side/lua).
+
+## Build instructions
+
+1. On the command line from the root of the repo, build the image from this directory with `docker build -t hello-haproxy -f ./examples/hello-haproxy/Dockerfile .`.
+2. Run the demo with:  
+    ```
+    docker run -it --rm --name hello-haproxy -p 8123:8123 --env LD_SDK_KEY="your-sdk-key" --env LD_FLAG_KEY="my-boolean-flag" hello-haproxy```
+    ```
+3. **Note:** the SDK key and flag key are passed with environment variables into the container. The `LD_FLAG_KEY` should be a boolean-type flag in your environment.
+4. Open `localhost:8123` in your browser. Toggle the flag on to see a change in the page (refresh the page.)
+
+You should receive the message: 
+> Feature flag is <true/false> for this user.

examples/hello-haproxy/haproxy.cfg

@@ -0,0 +1,15 @@
+global
+   lua-load /service.lua
+
+defaults
+    mode http
+    timeout connect 10s
+    timeout client 30s
+    timeout server 30s
+
+frontend proxy
+    bind 0.0.0.0:8123
+    use_backend default_backend
+
+backend default_backend
+    http-request use-service lua.launchdarkly

examples/hello-haproxy/service.lua

@@ -0,0 +1,50 @@
+print "loaded"
+
+local os = require("os")
+local ld = require("launchdarkly_server_sdk")
+
+
+-- Set YOUR_SDK_KEY to your LaunchDarkly SDK key.
+local YOUR_SDK_KEY = ""
+
+-- Set YOUR_FEATURE_KEY to the feature flag key you want to evaluate.
+local YOUR_FEATURE_KEY = "my-boolean-flag"
+
+
+-- Allows the LaunchDarkly SDK key to be specified as an environment variable (LD_SDK_KEY)
+-- or locally in this example code (YOUR_SDK_KEY).
+function get_key_from_env_or(name, existing_key)
+    if existing_key ~= nil and existing_key ~= "" then
+        core.Debug("Using LaunchDarkly SDK key from service.lua file")
+        return existing_key
+    end
+
+    local env_key = os.getenv("LD_" .. name)
+    if env_key ~= nil and env_key ~= "" then
+        core.Debug("Using LaunchDarkly SDK key from LD_" .. name .. " environment variable")
+        return env_key
+    end
+
+    core.log(core.crit, "LaunchDarkly SDK key not provided! SDK won't be initialized.")
+    return ""
+end
+
+local config = {}
+local client = ld.clientInit(get_key_from_env_or("SDK_KEY", YOUR_SDK_KEY), 1000, config)
+
+core.register_service("launchdarkly", "http", function(applet)
+    applet:start_response()
+
+    local user = ld.makeContext({
+        user =  {
+            key = "example-user-key",
+            name = "Sandy"
+        }
+    })
+
+    if client:boolVariation(user, get_key_from_env_or("FLAG_KEY", YOUR_FEATURE_KEY), false) then
+        applet:send("<p>Feature flag is true for this user</p>")
+    else
+        applet:send("<p>Feature flag is false for this user</p>")
+    end
+end)