Merge pull request 'add-readme-to-docker-compose' (#6) from add-readme-to-docker-compose into master

Reviewed-on: #6

.gitignore

@@ -2,6 +2,9 @@
 # Covers JetBrains IDEs: IntelliJ, RubyMine, PhpStorm, AppCode, PyCharm, CLion, Android Studio, WebStorm and Rider
 # Reference: https://intellij-support.jetbrains.com/hc/en-us/articles/206544839
 
+# pyenv
+.python-version
+
 # User-specific stuff
 .idea/**/workspace.xml
 .idea/**/tasks.xml
@@ -206,6 +209,8 @@ venv/
 ENV/
 env.bak/
 venv.bak/
+!docker-compose/examples/*/env
+!docker-compose/{{ cookiecutter.__project_slug }}/env
 
 # Spyder project settings
 .spyderproject

README.md

@@ -2,17 +2,17 @@
 
 Project directory structure templates for the Python Cookiecutter package.
 
-## What's Cookiecutter?
+# What's Cookiecutter?
 
 The Python package [Cookiecutter](https://github.com/cookiecutter/cookiecutter) assists in creating directory structure for whatever purpose you need such as for example a new Python project, an Ansible role or a `docker-compose` project - anything really that benefits from a unifirm reproducible directory structure. If you've ever wanted to put project structure best practices into version control then Cookiecutter's here to help.
 
 Cookiecutter is governed by so-called Cookiecutter templates, most of its magic inside Cookiecutter templates happens via the [Jinja2 template engine](https://palletsprojects.com/p/jinja/). You'll feel right at home if you're familiar with Ansible.
 
-## Repo layout
+# Repo layout
 
 Each subdirectory in this repo is a Cookiecutter template, you'll recognize them from their telltale `cookiecutter.json` files. Directories usually also have a readme file explaining more about each individual template.
 
-## Get started
+# Get started
 
 Get Cookiecutter like so:
 ```
@@ -57,3 +57,176 @@ The end result is a directory structure that has everything you need to hit the
     └── env
         └── fully.qualified.domain.name.example
 ```
+
+# Developing
+
+To change Cookiecutter templates get yourself an environment then make, test and commit your changes. First things first, the environment.
+
+## Environment
+
+Get yourself a Python virtual environment. In this example we're assuming you're running a Linux operating system and you'll be using [pyenv](https://github.com/pyenv/pyenv) to manage virtual environments.
+
+### pyenv
+
+- Install pyenv with what they are calling their automatic installer. Feel free to also read up on pyenv on their [GitHub project page](https://github.com/pyenv/pyenv).
+    ```
+    curl https://pyenv.run | bash
+    ```
+
+- Following the installer's instruction add at least the following commands to your `~/.bashrc` file
+    ```
+    export PYENV_ROOT="$HOME/.pyenv"
+    command -v pyenv >/dev/null || export PATH="$PYENV_ROOT/bin:$PATH"
+    eval "$(pyenv init -)"
+    ```
+
+- You will also likely want to add this line which will make sure pyenv auto-activates venvs when you navigate into certain directories. More on that down at [venv](#venv).
+    ```
+    eval "$(pyenv virtualenv-init -)"
+    ```
+
+- Also make sure `~/.bashrc` gets loaded for example by including this in a `~/.bash_profile` file
+    ```
+    [[ -f ~/.bashrc ]] && . ~/.bashrc
+    ```
+
+- Reload `~/.bashrc`
+    ```
+    source ~/.bashrc
+    ```
+
+### Python
+
+- Update pyenv's package list
+    ```
+    pyenv update
+    ```
+- Pick a Python version you like, for example copy-paste `3.11.4`:
+    ```
+    pyenv install --list | less
+
+    ...
+    3.10.12
+    3.11.0
+    3.11-dev
+    3.11.1
+    3.11.2
+    3.11.3
+    3.11.4
+    3.12.0b2
+    3.12-dev
+    3.13-dev
+    ...
+    ```
+- Install Python, wait for compilation to finish on your machine
+    ```
+    pyenv install 3.11.4
+    ```
+
+### Repo
+
+- Clone this repo
+    ```
+    git clone https://quico.space/Quico/py-cookiecutter-templates.git ~/py-cookiecutter-templates
+    ```
+
+### venv
+
+- Create a virtual environment where `3.11.4` is the Python version you want to use in this venv and `cookiecutter-3.11.4` is the name of your venv. Adding or dropping the Python version from your venv name comes down to personal preference.
+    ```
+    pyenv virtualenv 3.11.4 cookiecutter-3.11.4
+    ```
+
+- In your repo path `~/py-cookiecutter-templates` create a `.python-version` file to tell pyenv to always activate your desired venv when inside this dir.
+    ```
+    cd ~/py-cookiecutter-templates
+    pyenv local cookiecutter-3.11.4
+    ```
+    pyenv will immediately prefix your shell's `${PS1}` prompt with the venv name.
+    ```
+    (cookiecutter-3.11.4) [✔ 23:19 user@machine py-cookiecutter-templates]$ 
+    ```
+    It will deactivate the venv and drop its prefix as soon as you navigate out of this dir.
+    ```
+    (cookiecutter-3.11.4) [✔ 23:19 user@machine py-cookiecutter-templates]$ cd
+    [✔ 23:19 user@machine ~]$ 
+    ```
+    For now though stay in `~/py-cookiecutter-templates`, you're going to want to pip-install [cookiecutter](https://pypi.org/project/cookiecutter).
+
+- Upgrade `pip`
+    ```
+    pip install --upgrade pip
+    ```
+
+- Install [cookiecutter](https://pypi.org/project/cookiecutter)
+    ```
+    pip install cookiecutter
+    ```
+
+All done, your environment is set up.
+
+## Change
+
+Make some code changes, for example to the Docker Compose Cookiecutter template. When you're happy run your local Cookiecutter template to see how your changes are rendering.
+
+- Create `/tmp/cookiecutter-docker-compose`
+    ```
+    mkdir '/tmp/cookiecutter-docker-compose'
+    ```
+
+- Render a Docker Compose directory into your output directory, answer Cookiecutter's prompts:
+    ```
+    # cookiecutter ~/py-cookiecutter-templates \
+        --directory docker-compose \
+        --output-dir /tmp/cookiecutter-docker-compose
+
+    project_slug [dir-name]: mydir
+    service [mydir]: myservice
+    component_list [myservice]: mycomponent_one,mycomponent_two
+    context [ctx]: ux_novosibirsk
+    ```
+
+- Observe that in `/tmp/cookiecutter-docker-compose` you now have your rendered Docker Compose dir:
+    ```
+    # tree /tmp/cookiecutter-docker-compose
+
+    /tmp/cookiecutter-docker-compose
+    └── mydir
+        ├── build-context
+        │   ├── mycomponent_one
+        │   │   ├── docker-data
+        │   │   ├── Dockerfile
+        │   │   └── extras
+        │   └── mycomponent_two
+        │       ├── docker-data
+        │       ├── Dockerfile
+        │       └── extras
+        ├── common-settings.yml
+        ├── docker-compose.override.yml
+        ├── docker-compose.yml
+        └── env
+            └── fqdn_context.env.example
+    ```
+
+- For rapid testing you will most likely want to not type prompt answers repeatedly. Give them as command line arguments instead, also specify `--no-input` to suppress prompts:
+    ```
+    cookiecutter ~/py-cookiecutter-templates \
+        --no-input \
+        --directory docker-compose \
+        --output-dir /tmp/cookiecutter-docker-compose \
+        project_slug=mydir \
+        service=myservice \
+        component_list=mycomponent_one,mycomponent_two \
+        context=ux_novosibirsk
+    ```
+
+## Commit prep
+
+When you're about ready to commit changes into this repo check the following bullet points.
+
+- Did you update the [Cookiecutter template README.md file](docker-compose/README.md), here for example for Docker Compose?
+    - Change in behavior?
+    - An updated example directory layout?
+    - Updated example file content?
+- Did you commit a new completely rendered example directory structure into [docker-compose/examples](docker-compose/examples) dir?
+- Did you change something that affects existing example directories? If so rerender them.

docker-compose/README.md

@@ -13,6 +13,10 @@ project_slug [dir-name]: grafana
 service [grafana]:
 component_list [grafana]: grafana,nginx
 context [ctx]: cncf
+Select build:
+1 - no
+2 - yes
+Choose from 1, 2 [1]: 
 ```
 
 Done, directory structure and files for your next `docker-compose` project are ready for you to hit the ground running.
@@ -60,13 +64,13 @@ Your four answers translate as follows into rendered files.
         ...
     ```
 
-4. The last prompt for a `context` is a generic string to help you distinguish deployments. It can be whatever you want such as for example a team name, here `cncf` which shows up as a preset in an example env file. It defaults to `ctx` just so it can't be empty.
+4. The `context` prompt is a generic string to help you distinguish deployments. It can be whatever you want such as for example a team name, here `cncf` which shows up as a preset in an example env file. It defaults to `ctx` just so it can't be empty.
     ```
     .
     └── grafana
         ...
         └── env
-            └── fully.qualified.domain.name.example           <---
+            └── fqdn_context.env.example                      <---
     ```
 
     Which then looks like:
@@ -75,6 +79,12 @@ Your four answers translate as follows into rendered files.
     ...
     ```
 
+5. Prompt `build` is a yes-no question. Cookiecutter will create a `README.md` file with copy-pastable Docker Compose commands pre-filled. If you answer `yes` to this prompt `README.md` will contain an example paragraph that explains the build process along the lines of:
+    ```
+    docker compose ... --profile 'build' build
+    ```
+    Whereas by answering `no` (or just hitting `<Enter>` to accept the default of `no`) no such paragraph will be added to the example Markdown file. Build instructions are only really needed if you need to locally build a derivative image.
+
 Also check out [the Caveats section](#caveats) at the end to learn what this template does not do well.
 
 ## Result
@@ -132,7 +142,7 @@ Consider Cookiecutter's project directory and rendered files a starting point. I
 
 Imagine if you will a service that consists of [Infinispan](https://infinispan.org/) among other things. In Docker Hub's content-addressable image store Infinispan's location is at `infinispan/server` so you obviously want that exact string with a forward slash to show up in your `docker-compose.yml` as the `image:` key's value, same with your `Dockerfile`. The `image:` key's value comes from what you enter in Cookiecutter's `component_list` prompt. Component strings are then used to also pre-fill the `volumes:` key.
 
-This will cause obvious issues (but the `image:` key is kinda correct):
+_**This**_ will cause obvious issues (but the `image:` key is kinda correct):
 ```
 services:
     infinispan/server:
@@ -140,7 +150,7 @@ services:
         container_name: "cacheman-infinispan/server-${CONTEXT}"
 ```
 
-This won't cause issues (but you'll have to then go in and manually change the `image:` key to use `infinispan/server`):
+_**This**_ won't cause issues (but you'll have to then go in and manually change the `image:` key to use `infinispan/server`):
 ```
 services:
     infinispan:

docker-compose/cookiecutter.json

@@ -6,5 +6,6 @@
     "component_list": "{{ cookiecutter.__service_slug }}",
     "__component_list_slug": "{{ cookiecutter.component_list.lower().replace(' ', '_').replace('-', '_') }}",
     "context": "ctx",
-    "__context_slug": "{{ cookiecutter.context.lower().replace(' ', '_').replace('-', '_') }}"
+    "__context_slug": "{{ cookiecutter.context.lower().replace(' ', '_').replace('-', '_') }}",
+    "build": ["no", "yes"]
 }

docker-compose/examples/grafana/docker-compose.yml

@@ -5,15 +5,18 @@ services:
         networks:
             grafana-default:
         profiles: ["full", "grafana"]
+        depends_on:
+            nginx:
+                condition: service_healthy
         extends:
             file: common-settings.yml
             service: common-settings
         ports:
             # - "8080:80"
         volumes:
-            # - /opt/docker-data/grafana-grafana-${CONTEXT}/grafana/data/db:/usr/lib/grafana
+            # - /opt/docker-data/grafana-${CONTEXT}/grafana/data/db:/usr/lib/grafana
-            # - /opt/docker-data/grafana-grafana-${CONTEXT}/grafana/data/logs:/var/log/grafana
+            # - /opt/docker-data/grafana-${CONTEXT}/grafana/data/logs:/var/log/grafana
-            # - /opt/docker-data/grafana-grafana-${CONTEXT}/grafana/config:/etc/grafana
+            # - /opt/docker-data/grafana-${CONTEXT}/grafana/config:/etc/grafana
         environment:
             # GRAFANA_USER: ${GRAFANA_USER}
             # GRAFANA_PASSWORD: ${GRAFANA_PASSWORD}
@@ -23,15 +26,21 @@ services:
         networks:
             grafana-default:
         profiles: ["full", "nginx"]
+        healthcheck:
+            test: ["CMD", "fping", "--count=1", "${GRAFANA_VIP}", "--period=500", "--quiet"]
+            interval: 3s
+            timeout: 1s
+            retries: 60
+            start_period: 2s
         extends:
             file: common-settings.yml
             service: common-settings
         ports:
             # - "8080:80"
         volumes:
-            # - /opt/docker-data/grafana-nginx-${CONTEXT}/nginx/data/db:/usr/lib/nginx
+            # - /opt/docker-data/grafana-${CONTEXT}/nginx/data/db:/usr/lib/nginx
-            # - /opt/docker-data/grafana-nginx-${CONTEXT}/nginx/data/logs:/var/log/nginx
+            # - /opt/docker-data/grafana-${CONTEXT}/nginx/data/logs:/var/log/nginx
-            # - /opt/docker-data/grafana-nginx-${CONTEXT}/nginx/config:/etc/nginx
+            # - /opt/docker-data/grafana-${CONTEXT}/nginx/config:/etc/nginx
         environment:
             # NGINX_USER: ${NGINX_USER}
             # NGINX_PASSWORD: ${NGINX_PASSWORD}
@@ -44,4 +53,4 @@ networks:
         ipam:
             driver: default
             config:
-                # - subnet: 172.21.184.0/24
+                - subnet: ${SUBNET}

docker-compose/examples/grafana/env/fqdn_context.env.example

@@ -6,6 +6,7 @@ CONTEXT=cncf
 # ---
 # GRAFANA_VERSION=x.y.z
 # NGINX_VERSION=x.y.z
+# GRAFANA_VIP=10.1.1.2
 
 
 
@@ -24,6 +25,16 @@ CONTEXT=cncf
 
 
 
+# Subnet to use for this Docker Compose project. Docker defaults to
+# container networks in prefix 172.16.0.0/12 which is 1 million addresses in
+# the range from 172.16.0.0 to 172.31.255.255. Docker uses 172.17.0.0/16 for
+# itself. Use any sensible prefix in 172.16.0.0/12 here except for Docker's
+# own 172.17.0.0/16.
+# ---
+SUBNET=172.30.95.0/24
+
+
+
 # See 'docker-compose.override.yml' for how to make a variable available in
 # a Dockerfile
 # ---

docker-compose/examples/hashicorpvault/docker-compose.yml

@@ -25,4 +25,4 @@ networks:
         ipam:
             driver: default
             config:
-                # - subnet: 172.21.184.0/24
+                - subnet: ${SUBNET}

docker-compose/examples/hashicorpvault/env/fqdn_context.env.example

@@ -5,6 +5,7 @@ CONTEXT=fsf
 # Set something sensible here and uncomment
 # ---
 # VAULT_VERSION=x.y.z
+# VAULT_VIP=10.1.1.2
 
 
 
@@ -23,6 +24,16 @@ CONTEXT=fsf
 
 
 
+# Subnet to use for this Docker Compose project. Docker defaults to
+# container networks in prefix 172.16.0.0/12 which is 1 million addresses in
+# the range from 172.16.0.0 to 172.31.255.255. Docker uses 172.17.0.0/16 for
+# itself. Use any sensible prefix in 172.16.0.0/12 here except for Docker's
+# own 172.17.0.0/16.
+# ---
+SUBNET=172.30.95.0/24
+
+
+
 # See 'docker-compose.override.yml' for how to make a variable available in
 # a Dockerfile
 # ---

docker-compose/{{ cookiecutter.__project_slug }}/README.md

@@ -0,0 +1,80 @@
+# {{ cookiecutter.__service_slug.capitalize() }} Docker Compose files
+
+Docker Compose files to spin up an instance of {{ cookiecutter.__service_slug.capitalize() }}.
+
+# How to run
+
+Add a `COMPOSE_ENV` file and save its location as a shell variable along with the location where this repo lives, here for example `/opt/containers/{{ cookiecutter.__project_slug }}` plus all other variables. At [env/fqdn_context.env.example](env/fqdn_context.env.example) you'll find an example environment file.
+
+When everything's ready start {{ cookiecutter.__service_slug.capitalize() }} with Docker Compose, otherwise head down to [Initial setup](#initial-setup) first.
+
+## Environment
+```
+export COMPOSE_DIR='/opt/containers/{{ cookiecutter.__project_slug }}'
+export COMPOSE_CTX='{{ cookiecutter.__context_slug }}'
+export COMPOSE_PROJECT='{{ cookiecutter.__service_slug }}-'"${COMPOSE_CTX}"
+export COMPOSE_FILE="${COMPOSE_DIR}"'/docker-compose.yml'{% if cookiecutter.build == "yes" %}
+export COMPOSE_OVERRIDE="${COMPOSE_DIR%/}"'/docker-compose.override.yml'{% endif %}
+export COMPOSE_ENV=<add accordingly>
+```
+
+{%- if cookiecutter.build == "yes" %}
+
+## Build
+
+```
+docker compose --project-name "${COMPOSE_PROJECT}" --file "${COMPOSE_FILE}" --file "${COMPOSE_OVERRIDE}" --env-file "${COMPOSE_ENV}" --profile 'build' build
+```
+{%- endif %}
+
+## Start
+
+```
+{%- if ',' in cookiecutter.__component_list_slug %}
+docker compose --project-name "${COMPOSE_PROJECT}" --file "${COMPOSE_FILE}" --env-file "${COMPOSE_ENV}" --profile 'full' up --detach
+{%- else %}
+docker compose --project-name "${COMPOSE_PROJECT}" --file "${COMPOSE_FILE}" --env-file "${COMPOSE_ENV}" up --detach
+{%- endif %}
+```
+
+# Initial setup
+
+We're assuming you run Docker Compose workloads with ZFS-based bind mounts. ZFS management, creating a zpool and setting adequate properties for its datasets is out of scope of this document.
+
+## Datasets
+
+Create ZFS datasets and set permissions as needed.
+
+* Parent dateset
+    ```
+    zfs create -o mountpoint=/opt/docker-data 'zpool/docker-data'
+    ```
+
+* Container-specific datasets
+    ```
+{%- if ',' in cookiecutter.__component_list_slug -%}
+{%- set components = cookiecutter.__component_list_slug.split(',') -%}
+{%- for component in components %}
+    zfs create -p 'zpool/docker-data/{{ cookiecutter.__service_slug }}-${COMPOSE_CTX}/{{ component }}/data/db'
+    zfs create -p 'zpool/docker-data/{{ cookiecutter.__service_slug }}-${COMPOSE_CTX}/{{ component }}/data/logs'
+    zfs create -p 'zpool/docker-data/{{ cookiecutter.__service_slug }}-${COMPOSE_CTX}/{{ component }}/config'
+{%- endfor -%}
+{%- else %}
+    zfs create -p 'zpool/docker-data/{{ cookiecutter.__service_slug }}-${COMPOSE_CTX}/{{ cookiecutter.__service_slug }}/data/db'
+    zfs create -p 'zpool/docker-data/{{ cookiecutter.__service_slug }}-${COMPOSE_CTX}/{{ cookiecutter.__service_slug }}/data/logs'
+    zfs create -p 'zpool/docker-data/{{ cookiecutter.__service_slug }}-${COMPOSE_CTX}/{{ cookiecutter.__service_slug }}/config'
+{%- endif %}
+    ```
+    When changing bind mount locations to real ones remember to also update `volumes:` in [docker-compose.yml](docker-compose.yml).
+
+* Change ownership
+    ```
+{%- set components = cookiecutter.__component_list_slug.split(',') -%}
+{% for component in components %}
+{%- if loop.first %}
+    chown -R 1000:1000 '/opt/docker-data/{{ cookiecutter.__service_slug }}-${COMPOSE_CTX}/{{ cookiecutter.__service_slug }}/data'
+{%- endif %}
+{%- endfor %}
+    ```
+
+When done head back up to [How to run](#how-to-run).

docker-compose/{{ cookiecutter.__project_slug }}/docker-compose.yml

@@ -1,6 +1,15 @@
 services:
 {%- if ',' in cookiecutter.__component_list_slug -%}
 {%- set components = cookiecutter.__component_list_slug.split(',') -%}
+{%- set ns = namespace(found=false) -%}
+{%- for component in components %}
+    {%- if loop.first -%}
+        {%- set ns.first_component = component -%}
+    {%- elif N is undefined -%}
+        {%- set ns.second_component = component -%}
+        {%- set N = 0 -%}
+    {%- endif -%}
+{%- endfor -%}
 {%- for component in components %}
     {{ component }}:
         image: "{{ component }}:${% raw %}{{% endraw %}{{ component.upper() }}_VERSION{% raw %}}{% endraw %}"
@@ -8,15 +17,29 @@ services:
         networks:
             {{ cookiecutter.__service_slug }}-default:
         profiles: ["full", "{{ component }}"]
+        {% if loop.first -%}
+        depends_on:
+            {{ ns.second_component }}:
+                condition: service_healthy
+        {%- else -%}
+        healthcheck:
+            test: ["CMD", "fping", "--count=1", "${% raw %}{{% endraw %}{{ ns.first_component.upper() }}_VIP{% raw %}}{% endraw %}", "--period=500", "--quiet"]
+            interval: 3s
+            timeout: 1s
+            retries: 60
+            start_period: 2s
+        {%- endif %}
         extends:
             file: common-settings.yml
             service: common-settings
         ports:
             # - "8080:80"
         volumes:
-            # - /opt/docker-data/{{ cookiecutter.__service_slug }}-{{ component }}-${CONTEXT}/{{ component }}/data/db:/usr/lib/{{ component }}
+            # When changing bind mount locations to real ones remember to
-            # - /opt/docker-data/{{ cookiecutter.__service_slug }}-{{ component }}-${CONTEXT}/{{ component }}/data/logs:/var/log/{{ component }}
+            # also update "Initial setup" section in README.md.
-            # - /opt/docker-data/{{ cookiecutter.__service_slug }}-{{ component }}-${CONTEXT}/{{ component }}/config:/etc/{{ component }}
+            # - /opt/docker-data/{{ cookiecutter.__service_slug }}-${CONTEXT}/{{ component }}/data/db:/usr/lib/{{ component }}
+            # - /opt/docker-data/{{ cookiecutter.__service_slug }}-${CONTEXT}/{{ component }}/data/logs:/var/log/{{ component }}
+            # - /opt/docker-data/{{ cookiecutter.__service_slug }}-${CONTEXT}/{{ component }}/config:/etc/{{ component }}
         environment:
             # {{ component.upper() }}_USER: ${% raw %}{{% endraw %}{{ component.upper() }}_USER{% raw %}}{% endraw %}
             # {{ component.upper() }}_PASSWORD: ${% raw %}{{% endraw %}{{ component.upper() }}_PASSWORD{% raw %}}{% endraw %}
@@ -33,9 +56,11 @@ services:
         ports:
             # - "8080:80"
         volumes:
-            # - /opt/docker-data/{{ cookiecutter.__service_slug }}-${CONTEXT}/data/db:/usr/lib/{{ cookiecutter.__service_slug }}
+            # When changing bind mount locations to real ones remember to
-            # - /opt/docker-data/{{ cookiecutter.__service_slug }}-${CONTEXT}/data/logs:/var/log/{{ cookiecutter.__service_slug }}
+            # also update "Initial setup" section in README.md.
-            # - /opt/docker-data/{{ cookiecutter.__service_slug }}-${CONTEXT}/config:/etc/{{ cookiecutter.__service_slug }}
+            # - /opt/docker-data/{{ cookiecutter.__service_slug }}-${CONTEXT}/{{ cookiecutter.__service_slug }}/data/db:/usr/lib/{{ cookiecutter.__service_slug }}
+            # - /opt/docker-data/{{ cookiecutter.__service_slug }}-${CONTEXT}/{{ cookiecutter.__service_slug }}/data/logs:/var/log/{{ cookiecutter.__service_slug }}
+            # - /opt/docker-data/{{ cookiecutter.__service_slug }}-${CONTEXT}/{{ cookiecutter.__service_slug }}/config:/etc/{{ cookiecutter.__service_slug }}
         environment:
             # {{ cookiecutter.__component_list_slug.upper() }}_USER: ${% raw %}{{% endraw %}{{ cookiecutter.__component_list_slug.upper() }}_USER{% raw %}}{% endraw %}
             # {{ cookiecutter.__component_list_slug.upper() }}_PASSWORD: ${% raw %}{{% endraw %}{{ cookiecutter.__component_list_slug.upper() }}_PASSWORD{% raw %}}{% endraw %}
@@ -49,4 +74,4 @@ networks:
         ipam:
             driver: default
             config:
-                # - subnet: 172.21.184.0/24
+                - subnet: ${SUBNET}

docker-compose/{{ cookiecutter.__project_slug }}/env/fqdn_context.env.example

@@ -8,6 +8,11 @@ CONTEXT={{ cookiecutter.__context_slug }}
 {% for component in components %}
 # {{ component.upper() }}_VERSION=x.y.z
 {%- endfor %}
+{%- for component in components %}
+{%- if loop.first %}
+# {{ component.upper() }}_VIP=10.1.1.2
+{%- endif %}
+{%- endfor %}
 
 
 
@@ -26,6 +31,16 @@ CONTEXT={{ cookiecutter.__context_slug }}
 
 
 
+# Subnet to use for this Docker Compose project. Docker defaults to
+# container networks in prefix 172.16.0.0/12 which is 1 million addresses in
+# the range from 172.16.0.0 to 172.31.255.255. Docker uses 172.17.0.0/16 for
+# itself. Use any sensible prefix in 172.16.0.0/12 here except for Docker's
+# own 172.17.0.0/16.
+# ---
+SUBNET=172.30.95.0/24
+
+
+
 # See 'docker-compose.override.yml' for how to make a variable available in
 # a Dockerfile
 # ---