Docker: show welcome page on port 80 when entrypoint.d is empty.

The entrypoint script now performs a default configuration when no useful
files are found in /docker-entrypoint.d/

The default configuration serves a welcome page in response to all
requests, using Markdown unless text/html is sent in the Accept header.

This provides a useful 'hello world' experience when running a Unit
container for the first time.

5 files changed, 136 insertions, 33 deletions

diff --git a/pkg/docker/docker-entrypoint.sh b/pkg/docker/docker-entrypoint.sh
index c670c2e6..4646409f 100755
--- a/pkg/docker/docker-entrypoint.sh
+++ b/pkg/docker/docker-entrypoint.sh
@@ -25,21 +25,23 @@ if [ "$1" = "unitd" ] || [ "$1" = "unitd-debug" ]; then
     if /usr/bin/find "/var/lib/unit/" -mindepth 1 -print -quit 2>/dev/null | /bin/grep -q .; then
         echo "$0: /var/lib/unit/ is not empty, skipping initial configuration..."
     else
-        if /usr/bin/find "/docker-entrypoint.d/" -mindepth 1 -print -quit 2>/dev/null | /bin/grep -q .; then
-            echo "$0: /docker-entrypoint.d/ is not empty, launching Unit daemon to perform initial configuration..."
-            /usr/sbin/$1 --control unix:/var/run/control.unit.sock
+        echo "$0: Launching Unit daemon to perform initial configuration..."
+        /usr/sbin/$1 --control unix:/var/run/control.unit.sock
 
-            for i in $(/usr/bin/seq $WAITLOOPS); do
-                if [ ! -S /var/run/control.unit.sock ]; then
-                    echo "$0: Waiting for control socket to be created..."
-                    /bin/sleep $SLEEPSEC
-                else
-                    break
-                fi
-            done
-            # even when the control socket exists, it does not mean unit has finished initialisation
-            # this curl call will get a reply once unit is fully launched
-            /usr/bin/curl -f -s -X GET --unix-socket /var/run/control.unit.sock http://localhost/
+        for i in $(/usr/bin/seq $WAITLOOPS); do
+            if [ ! -S /var/run/control.unit.sock ]; then
+                echo "$0: Waiting for control socket to be created..."
+                /bin/sleep $SLEEPSEC
+            else
+                break
+            fi
+        done
+        # even when the control socket exists, it does not mean unit has finished initialisation
+        # this curl call will get a reply once unit is fully launched
+        /usr/bin/curl -s -X GET --unix-socket /var/run/control.unit.sock http://localhost/
+
+        if /usr/bin/find "/docker-entrypoint.d/" -mindepth 1 -print -quit 2>/dev/null | /bin/grep -q .; then
+            echo "$0: /docker-entrypoint.d/ is not empty, applying initial configuration..."
 
             echo "$0: Looking for certificate bundles in /docker-entrypoint.d/..."
             for f in $(/usr/bin/find /docker-entrypoint.d/ -type f -name "*.pem"); do
@@ -69,29 +71,30 @@ if [ "$1" = "unitd" ] || [ "$1" = "unitd-debug" ]; then
             for f in $(/usr/bin/find /docker-entrypoint.d/ -type f -not -name "*.sh" -not -name "*.json" -not -name "*.pem" -not -name "*.js"); do
                 echo "$0: Ignoring $f";
             done
+        else
+            echo "$0: /docker-entrypoint.d/ is empty, creating 'welcome' configuration..."
+            curl_put /usr/share/unit/welcome/welcome.json "config"
+        fi
 
-            echo "$0: Stopping Unit daemon after initial configuration..."
-            kill -TERM $(/bin/cat /var/run/unit.pid)
+        echo "$0: Stopping Unit daemon after initial configuration..."
+        kill -TERM $(/bin/cat /var/run/unit.pid)
 
-            for i in $(/usr/bin/seq $WAITLOOPS); do
-                if [ -S /var/run/control.unit.sock ]; then
-                    echo "$0: Waiting for control socket to be removed..."
-                    /bin/sleep $SLEEPSEC
-                else
-                    break
-                fi
-            done
+        for i in $(/usr/bin/seq $WAITLOOPS); do
             if [ -S /var/run/control.unit.sock ]; then
-                kill -KILL $(/bin/cat /var/run/unit.pid)
-                rm -f /var/run/control.unit.sock
+                echo "$0: Waiting for control socket to be removed..."
+                /bin/sleep $SLEEPSEC
+            else
+                break
             fi
-
-            echo
-            echo "$0: Unit initial configuration complete; ready for start up..."
-            echo
-        else
-            echo "$0: /docker-entrypoint.d/ is empty, skipping initial configuration..."
+        done
+        if [ -S /var/run/control.unit.sock ]; then
+            kill -KILL $(/bin/cat /var/run/unit.pid)
+            rm -f /var/run/control.unit.sock
         fi
+
+        echo
+        echo "$0: Unit initial configuration complete; ready for start up..."
+        echo
     fi
 fi
 
diff --git a/pkg/docker/template.Dockerfile b/pkg/docker/template.Dockerfile
index 2ffc5a97..c6a72aa8 100644
--- a/pkg/docker/template.Dockerfile
+++ b/pkg/docker/template.Dockerfile
@@ -75,9 +75,10 @@ RUN set -ex \
     && ln -sf /dev/stdout /var/log/unit.log
 
 COPY docker-entrypoint.sh /usr/local/bin/
+COPY welcome.* /usr/share/unit/welcome/
 
 STOPSIGNAL SIGTERM
 
 ENTRYPOINT ["/usr/local/bin/docker-entrypoint.sh"]
-
+EXPOSE 80
 CMD ["unitd", "--no-daemon", "--control", "unix:/var/run/control.unit.sock"]
diff --git a/pkg/docker/welcome.html b/pkg/docker/welcome.html
new file mode 100644
index 00000000..9c4f8281
--- /dev/null
+++ b/pkg/docker/welcome.html
@@ -0,0 +1,45 @@
+<!DOCTYPE html>
+<html>
+    <head>
+        <title>Welcome to NGINX Unit</title>
+        <style type="text/css">
+            body { background: white; color: black; font-family: sans-serif; margin: 2em; line-height: 1.5; }
+            h1,h2 { color: #00974d; }
+            li { margin-bottom: 0.5em; }
+            pre { background-color: beige; padding: 0.4em; }
+            hr { margin-top: 2em; border: 1px solid #00974d; }
+            .indent { margin-left: 1.5em; }
+        </style>
+    </head>
+    <body>
+        <h1>Welcome to NGINX Unit</h1>
+        <p>Congratulations! NGINX Unit is installed and running.</p>
+        <h3>Useful Links</h3>
+        <ul>
+            <li><b><a href="https://unit.nginx.org/configuration/?referer=welcome&platform=docker">https://unit.nginx.org/configuration/</a></b><br>
+                To get started with Unit, see the <em>Configuration</em> docs, starting with
+                the <em>Quick Start</em> guide.</li>
+            <li><b><a href="https://unit.nginx.org/howto/docker/?referer=welcome&platform=docker">https://unit.nginx.org/howto/docker/</a></b><br>
+                For guidance about running <em>Unit in Docker</em> and tips for containerized
+                applications.
+            <li><b><a href="https://github.com/nginx/unit">https://github.com/nginx/unit</a></b><br>
+                See our GitHub repo to browse the code, contribute, or seek help from the
+                <a href="https://github.com/nginx/unit#community">community</a>.</li>
+        </ul>
+
+        <h2>Next steps</h2>
+
+        <h3>Check Current Configuration</h3>
+        <div class="indent">
+        <p>Unit's control API is currently listening for configuration changes
+           on the <a href="https://en.wikipedia.org/wiki/Unix_domain_socket">Unix socket</a> at
+           <b>/var/run/control.unit.sock</b> inside the container.<br>
+           To see the current configuration run:</p>
+        <pre>docker exec -ti <containerID> curl --unix-socket /var/run/control.unit.sock http://localhost/config</pre>
+        </div>
+
+        <hr>
+        <p><a href="https://unit.nginx.org/?referer=welcome&platform=docker">NGINX Unit &mdash; the universal web app server</a><br>
+        NGINX, Inc. &copy; 2023</p>
+    </body>
+</html>
diff --git a/pkg/docker/welcome.json b/pkg/docker/welcome.json
new file mode 100644
index 00000000..2a148da8
--- /dev/null
+++ b/pkg/docker/welcome.json
@@ -0,0 +1,25 @@
+{
+    "listeners": {
+        "*:80": {
+            "pass": "routes"
+        }
+    },
+
+    "routes": [
+        {
+            "match": {
+                "headers": {
+                    "accept": "*text/html*"
+                }
+            },
+            "action": {
+                "share": "/usr/share/unit/welcome/welcome.html"
+            }
+        },
+        {
+            "action": {
+                "share": "/usr/share/unit/welcome/welcome.md"
+            }
+        }
+    ]
+}
diff --git a/pkg/docker/welcome.md b/pkg/docker/welcome.md
new file mode 100644
index 00000000..fef3d152
--- /dev/null
+++ b/pkg/docker/welcome.md
@@ -0,0 +1,29 @@
+Welcome to NGINX Unit
+=====================
+
+Congratulations! NGINX Unit is installed and running.
+
+Useful Links
+------------
+
+ * https://unit.nginx.org/
+   - Get started with the 'Configuration' docs, starting with the 'Quick Start' guide.
+
+ * https://unit.nginx.org/howto/docker/
+   - Guidance for running Unit in a container and tips for containerized applications.
+
+ * https://github.com/nginx/unit
+   - See our GitHub repo to browse the code, contribute, or seek help from the community.
+
+Current Configuration
+---------------------
+Unit's control API is currently listening for configuration changes on the Unix socket at
+`/var/run/control.unit.sock` inside the container.
+
+Read the current configuration with
+```
+docker exec -ti <containerID> curl --unix-socket /var/run/control.unit.sock http://localhost/config
+```
+
+---
+NGINX Unit - the universal web app server