Update Docker README to match reality.

pkg/docker/README

@@ -21,53 +21,109 @@ the required files, then build the container and push it to your repo.
 Running
 =======
 
+Environment Variables
+---------------------
+
 The container will accept the following variables at startup:
 
-PGADMIN_SETUP_EMAIL
--------------------
+*PGADMIN_DEFAULT_EMAIL*
 
-This is the email address used when setting up the initial administrator account to login to pgAdmin.
+This is the email address used when setting up the initial administrator account
+to login to pgAdmin. This variable is required and must be set at launch time.
 
-PGADMIN_SETUP_PASSWORD
-----------------------
+*PGADMIN_DEFAULT_PASSWORD*
 
-This is the password used when setting up the initial administrator account to login to pgAdmin.
+This is the password used when setting up the initial administrator account to
+login to pgAdmin. This variable is required and must be set at launch time.
 
-PGADMIN_ENABLE_TLS
-------------------
+*PGADMIN_ENABLE_TLS*
 
-Default: unset
+Default: <null>
 
-If not set, the container will listen on port 8080 for connections in insecure HTTP protocol.
-If set to any value, the container will listen on port 8443 for TLS connections.
+If left un-set, the container will listen on port 80 for connections in plain
+text. If set to any value, the container will listen on port 443 for TLS
+connections.
 
-When TLS is enabled, a certificate and key must be provided.
-Typically these should be stored on the host file system and mounted from the container.
-The expected paths are `/certs/server.crt` and `/certs/server.key`.
+When TLS is enabled, a certificate and key must be provided. Typically these
+should be stored on the host file system and mounted from the container. The
+expected paths are /certs/server.crt and /certs/server.key
 
-You need to explicitly map these ports with `-p` option to some port at your machine.
+*PGADMIN_LISTEN_PORT*
+
+Default: 80 or 443 (if TLS is enabled)
+
+Allows the port that the server listens on to be set to a specific value rather
+than using the default.
+
+*GUNICORN_THREADS*
+
+Default: 25
+
+Adjust the number of threads the Gunicorn server uses to handle incoming
+requests. This should typically be left as-is, except in highly loaded systems
+where it may be increased.
+
+Mapped Files and Directories
+----------------------------
+
+The following files or directories can be mapped from the container onto the
+host machine to allow configuration to be customised and shared between
+instances:
+
+*/var/lib/pgadmin*
+
+This is the working directory in which pgAdmin stores session data, user files,
+configuration files, and it's configuration database. Mapping this directory
+onto the host machine gives you an easy way to maintain configuration between
+
+invocations of the container.
+
+*/pgadmin4/config_local.py*
+
+This file can be used to override configuration settings in pgAdmin. Settings
+found in config.py can be overridden with deployment specific values if
+required.
+
+*/pgadmin4/servers.json*
+
+If this file is mapped, server definitions found in it will be loaded at launch
+time. This allows connection information to be pre-loaded into the instance of
+pgAdmin in the container.
+
+*/certs/server.cert*
+
+If TLS is enabled, this file will be used as the servers TLS certificate.
+
+*/certs/server.key*
+
+If TLS is enabled, this file will be used as the key file for the servers TLS
+certificate.
 
 Examples
-========
+--------
 
 Run a simple container over port 80:
 
-```console
-docker run -p 80:8080 \
-           -e "PGADMIN_SETUP_EMAIL=user@domain.com" \
-           -e "PGADMIN_SETUP_PASSWORD=SuperSecret" \
-           -d pgadmin4
 ```
-
-Run a TLS secured container using a shared config/storage directory in /private/var/lib/pgadmin on the host:
-
-```console
-docker run -p 443:8443 \
-           -v "/private/var/lib/pgadmin:/var/lib/pgadmin" \
-           -v "/path/to/certificate.cert:/certs/server.cert" \
-           -v "/path/to/certificate.key:/certs/server.key" \
-           -e "PGADMIN_SETUP_EMAIL=user@domain.com" \
-           -e "PGADMIN_SETUP_PASSWORD=SuperSecret" \
-           -e "PGADMIN_ENABLE_TLS=1" \
-           -d pgadmin4
+    docker pull dpage/pgadmin4
+    docker run -p 80:80 \
+        -e "PGADMIN_DEFAULT_EMAIL=user@domain.com" \
+        -e "PGADMIN_DEFAULT_PASSWORD=SuperSecret" \
+        -d dpage/pgadmin4
+```
+Run a TLS secured container using a shared config/storage directory in
+/private/var/lib/pgadmin on the host, and servers pre-loaded from
+/tmp/servers.json on the host:
+
+```
+    docker pull dpage/pgadmin4
+    docker run -p 443:443 \
+        -v "/private/var/lib/pgadmin:/var/lib/pgadmin" \
+        -v "/path/to/certificate.cert:/certs/server.cert" \
+        -v "/path/to/certificate.key:/certs/server.key" \
+        -v "/tmp/servers.json:/servers.json" \
+        -e "PGADMIN_DEFAULT_EMAIL=user@domain.com" \
+        -e "PGADMIN_DEFAULT_PASSWORD=SuperSecret" \
+        -e "PGADMIN_ENABLE_TLS=True" \
+        -d dpage/pgadmin4
 ```