diff --git a/Dockerfile b/Dockerfile
index 201e69d..1b65d5d 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -17,7 +17,7 @@ RUN apt update && apt -y install software-properties-common && add-apt-repositor
 
 # run Ansible commands
 COPY ./requirements.yaml ./playbook.yaml ./
-RUN ansible-galaxy install -r requirements.yaml && ansible-playbook -i,localhost playbook.yaml --tags "all" && rm -f ./*.yaml
+RUN ansible-galaxy install -r requirements.yaml && ansible-playbook -vvvv -i,localhost playbook.yaml --tags "all" && rm -f ./*.yaml
 
 # Custom Desktop Background - replace bg_custom.png on disk with your own background image
 COPY ./bg_fairy_penguins_1600x800.png /usr/share/backgrounds/bg_default.png
diff --git a/playbook.yaml b/playbook.yaml
index 3e0db30..2171574 100644
--- a/playbook.yaml
+++ b/playbook.yaml
@@ -78,49 +78,7 @@
     - role: webarchitect609.google_chrome
 
 -
-  # install firefox
-  hosts: localhost
-  connection: local
-  gather_facts: yes
-  tags:
-    - install_firefox
-
-  vars:
-    firefox_profiles:
-      default:
-        extensions:
-          - ublock-origin
-        preferences:
-          network.cookie.cookieBehavior: 1
-          privacy.donottrackheader.enabled: true
-          datareporting.healthreport.uploadEnabled: false
-      secondprofile:
-        extensions:
-          - adblock-plus
-        preferences:
-          privacy.donottrackheader.enabled: false
-          privacy.trackingprotection.enabled: false
-          signon.rememberSignons: false
-          datareporting.healthreport.uploadEnabled: false
-
-  tasks:
-  - name: Get disk usage
-    shell: df -h
-    register: disk_usage
-  - name: Display disk usage
-    debug:
-      msg: "{{ disk_usage.stdout }}"
-
-  pre_tasks:
-  - name: Update apt packages
-    apt:
-      update_cache: yes
-
-  roles:
-    - role: staticdev.firefox
-
--
-  # install keychain, git, and @capsulecorplab .vimrc and .gitconfig
+  # install keychain, git, nix, and @capsulecorplab .vimrc and .gitconfig
   hosts: localhost
   connection: local
   gather_facts: yes
@@ -134,11 +92,14 @@
     keychain_version_expected: "{{ keychain_version }}.."
 
   tasks:
-  - name: Add git PPA
-    shell: add-apt-repository ppa:git-core/ppa
-  - name: Install git
+  - name: Install nix-bin # see https://moonpiedumplings.github.io/projects/setting-up-kasm/#customized-kasm-images
     apt:
-      name: git
+      name: nix-bin
+      update_cache: yes
+  - name: Add kasm-user to nix-users group
+    shell: usermod -aG nix-users kasm-user
+  - name: Install git with nix
+    shell: nix profile install nixpkgs#git --extra-experimental-features nix-command --extra-experimental-features flakes
   - name: Install Git Bash Completion
     apt:
       name: bash-completion
@@ -151,14 +112,14 @@
     apt:
       name: iputils-ping
       update_cache: yes
-  - name: Get git version
-    shell: git version | sed 's/[[:alpha:]|(|[:space:]]//g'
-    register: installed_git_version
   - name: Get keychain version
     shell:
       cmd: keychain -V 2> >(grep -i keychain) 2> >(sed 's/[[:alpha:]|(|[:space:]]//g') | fgrep '*' | sed 's/[*~://]//g'
       executable: /bin/bash
     register: installed_keychain_version
+  - name: Get git version
+    shell: git version | sed 's/[[:alpha:]|(|[:space:]]//g'
+    register: installed_git_version
   - name: Display git and keychain versions
     debug:
       msg: "git = {{ installed_git_version.stdout }} | keychain = {{ installed_keychain_version.stdout }}"
diff --git a/requirements.yaml b/requirements.yaml
index 46d4674..d33accb 100644
--- a/requirements.yaml
+++ b/requirements.yaml
@@ -3,6 +3,5 @@
 - irixjp.role_example_hello           # https://galaxy.ansible.com/irixjp/role_example_hello
 - grzegorznowak.nvm_node              # https://galaxy.ansible.com/grzegorznowak/nvm_node
 - webarchitect609.google_chrome       # https://galaxy.ansible.com/webarchitect609/google_chrome
-- staticdev.firefox                   # https://galaxy.ansible.com/staticdev/firefox
 - gantsign.visual-studio-code         # https://galaxy.ansible.com/gantsign/visual-studio-code
 ...